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/diy/ - Do It Yourself



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old thread >>1198346

pastebin.com/9UgLjyND

>I'm new to electronics, where to get started?
There are several good books and YouTube channels that are commonly recommended for beginners and those wanting to learn more, many with advanced techniques. The best way to get involved in electronics is just to make stuff. Don't be afraid to get your hands dirty.

>What books are there?

Beginner:
Getting Started in Electronics Forrest Mims III
Make: Electronics Charles Platt
How to Diagnose Fix Everything Electronic Michael Jay Greier

Intermediate:
All New Electronics Self-Teaching Guide: Kybett, Boysen
Practical Electronics for Inventors: Paul Scherz and Simon Monk

Advanced:
The Art of Electronics by Paul Horowitz

>What YouTube channels are there?
https://www.youtube.com/user/mjlorton
https://www.youtube.com/user/paceworldwide
https://www.youtube.com/user/eevblog
https://www.youtube.com/user/EcProjects
https://www.youtube.com/user/greatscottlab
https://www.youtube.com/user/AfroTechMods
https://www.youtube.com/user/Photonvids
https://www.youtube.com/user/sdgelectronics
https://www.youtube.com/user/TheSignalPathBlog

>What websites feature electronics projects or ideas?
http://adafruit.com
http://instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/

>Where do I get components and lab equipment from?
digikey.com
jameco.com
sparkfun.com
ramseyelectronics.com
allelectronics.com
futurlec.com
ladyada.net/library/procure/hobbyist.html
mouser.com
alliedelec.com
newark.com
ebay.com

>What circuit sim software do you use?
This mostly comes down to personal preference. These are the most common ones though:
NI Multisim
LTSpice
CircuitLab
iCircuit for Macs

>What software should I use to layout boards?
Circuit Wizard
ExpressPCB
EAGLE
KiCad
>>
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>>1204692
How do get rid of these sick ads at the bottom of the page that have no place on a blue board?
>>
>>1204670
depending on the topology it can limit your operating range. that is to say, you'll only have zvs under certain conditions so you may end up having to design for full switching losses anyway. also it's more harder.
>>
>>1204699
you didn't have to post an example, just install an ad-blocker an delete that pic.
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>>1204702
done, thank you.
>>
Is it possible to use a pressure sensor to sense weights?
>>
> just install an ad-blocker an delete that pic

make sure it's ublock, and not ad-block plus, coz the latter slows down your browser a lot more, esp of you have a lot of tabs open.
>>
>>1204707

if you make a contraption like a bicycle pump to convert weight to pressure. much easier to get a strain gauge. just ask your dealer to sell you one of his old scales, and take out the strain gauge.
>>
>>1204692
>want to make a kite camera thing to map my university
>cool I just need a micro controller, camera, battery and image processing data libraries
>lets use a raspberry pi
>using a a raspberry pi, cheap camera and lithium battery is more expensive than just buying a camera, tying to a kite and set to record.
>without taking the time coding the data I/O and conversion from camera to storage.
>if I use a cent range micro processor I'll have to code in assembly from scratch
just fuck my life
>>
>>1204714
Use a PIC. About $1, can code in C, lots of functionality. Only issue is they're a bitch to interface with.
>>
>>1204776
do you rec any digital cameras? A tiny weeny one without anything, just a sensor and no bullshit.
>bitch to interface with
:(
>>
>>1204778
I got nothing about cameras. The IO in circuit isn't an issue, it's just programming it. You can buy the proprietary USB interface (PICkit) for around $50 new, cheaper used, or get a knockoff.

I made my own called the USBPicProg. To do that you need another PIC programmed as the bootloader. So to program that one I made a JDM programmer. The most expensive part is a pigtailed USB and DB9 serial cable.

I made my own USB
>>
>>1204714
>>1204776
I'd argue that simple PICs are more natural and expressive when coded in assembly. Use C with AVRs.
>>
>>1204785
What do you mean? What's the difference between the two that necessitates a change in language?
>>
>>1204785
>simple PICs are more natural and expressive when coded in assembly

true but irrelevant. if you're making a thing that flashes an LED when someone pushes a button, a PIC is great. but to handle cameras, media storage, and image manipulation software, a PIC is completely useless in every language.
>>
>>1204637
Soylent has too much soy (they changed the recipe so 100% of the protein is soy).

Go with Huel. Way more protein, and none of it is soy. I don't know when they started shipping in the US but it's only a few dollars difference.
>>
I plan to build a coil gun. Few short questions:

According to what I found while googling, the strength of an electromagnet is proportional to the coils and the current ("ampere-turns"). Then why do others use capacitors to induce a really high voltage for a short time in order to create a strong magnetic field though the voltage actually doesn't matter? That can't be right.

How do I actually determine how much voltage I want to send through the coil? 20V? 50? 100? 300? IIRC some dude on YT for example had a gun with a single coil that used 300V, while electroboom uses 75V. I decided to go with two 450V, 470uF capacitors, but I'm not confident in my decision.

I can't figure out if the D203S IR sensor is default opened or closed. As in, if there's some IR light hitting on the sensor does it send a signal or does it send the signal if there's no light is hitting the sensor?
>>
>>1204797
>What's the difference between the two that necessitates a change in language?

I'm not that guy, but assembly gives you direct control over everything, and if timing has to be precise you can make it precise.

C is way easier to program, of course.

I do lots of AVR work, and all of it in assmbly, partly because I've always done it like that, and my kind of projects fit perfectly with assembly most of the time. Use C when you can, assembly when you have to or simply want to because it's fun. And I'm not dick-waving; assembly on an AVR actually is fun, at least to me.
>>
>>1204972
voltage is the difference of potential energy between two points, it's not something you "send through a circuit". Google "Ohm's law", it will answer some of your doubts. Or even better read the first few chapters of any book on electromagnetism.
>>
>>1204972
>though the voltage actually doesn't matter? That can't be right.
Getting lots of current through a coil quickly requires high voltage.

>How do I actually determine how much voltage I want to send through the coil?
You could google coil gun simulators.

>D203S IR sensor is default opened or closed.
This is for that same coil toy? Get a different sensor. PIR sensors are intended for detecting moving people etc. and have linear output. They also react to changes only.
>>
hey
Sorry, I know it's kinda off-topic, but I have a question. Those who ever fucked around with microwave oven transformers, how thick was the original wire in it? Was there more than 20 meters of wire in one? I'm making a filter but enameled wire is damn expensive nowadays.
>>
>>1204981
I see. Thanks for the help!
>>
>>1204977
>it's not something you "send through a circuit"
except it is
>>
>>1204999
I'd say you can send a signal through a circuit, not a voltage.
>>
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>get job at electronics company
>'You'll start off with basic stuff and work your way up to soldering/reworking, testing and using the smt/flow soldering/oven machinery in the future'
>second week I was taught how to solder and started on reworking and fitting surface mount components
>next week I'm onto test
>now I'm learning how to use the SMT machine
>>
>>1204988

the secondary of an MOT has way more than 20 meters of wire. getting it out intact, tho, requires you either saw off one end, or break the welds. i suppose it's possible to unwind it instead, but the top layers will likely need to be destroyed.
>>
>>1204798
>>1204781
I'd need ram about the size of the images I'll be sending to the SD card I think.
>>1204798
What do you recommed? My Micro-processor/controller teacher is a useless fuck that teaches us to use a 40y.o 8051. I have no idea of other chips capabilities
>>
>>1205007

and once you've mastered all these simple robot tasks, then the mind-numbing boredom sets in. and when you realize there is zero prospects for advancement, you'll wish you hadn't smoked so much pot you couldn't even finish HS. might as well off yourself now. avoid all the disappointment and depression.
>>
>>1205054
>What do you recommed?

since you dont wanna be writing libraries for handling cameras, files systems, or image manipulation, you need a platform that has ready-made libs for all these things. a raspi seems the most obvious choice.
>>
>>1205061
:( rip monies
>>
Rookie here. So I just made the workbench power supply from an old pc power supply. The 12V dc output gives 18A. If I connect a 12v fan that needs lets say 2 amps to the power supply the fan only draws 2 amps even tho the power supply can supply 18? I dont want to break the fan.
>>
My hot air station comes on Monday and I need solder past for soldering SMD stuff.
However I haven't bought or used solder paste in my life, what brand do you recommend? Where can I get it from?
Louis Rossman (The Mac repair guy) recommends Amtech solder paste, but I'll probably have to pay shipping to yurop and end costing me around 60€ or more for 35 grams. What do?
https://mailin.repair/amtech-syntech-solder-paste-sn63-pb3735g-syringe.html
>>
>>1205075
Your wall socket 'gives' 120V and 10 ampere which is 1200 watt. Will it 'break' a 60 watt lightbulb?
>>
>>1205079
Thats what I thought. Just wanted to make sure. Thanks.
>>
>>1205055
Thus spoke the one-track mind.
>>
Does anyone know where to find a 10khz sample rate ammeter with data logging without spending $10k on industrial equiptment? I'd prefer not to have to build and calibrate one.
>>
>>1205079
what the fuck does that have to do with anything?
i could put a 10w bulb from my car into the wall and it wouldn't blow up? fucking retarded

>>1205075
if your supply is a voltage source (pretty much all of them) then you match the voltage and it draws the current it needs.
if your supply is a current source (e.g. an led driver is typically a current source because an led's current draw increases as it heats up, so the current must be regulated somehow) then it will supply as much voltage as it can in order to maintain whatever current it is set to give.

pc power supply is a voltage source, you have matched the voltages, you will be ok.
>>
>>1205112
Buy a current probe (or use a current sense resistor + instrumentation amplifier) for an oscilloscope with data logging?
>>
>>1205129
>i could put a 10w bulb from my car into the wall and it wouldn't blow up? fucking retarded

You can put it in the wall and it won't blow up but if you connect it electrically to the outlet in a manner that allows the 120vac to flow through the bulb filament it will flash and pop and become a glass envelope with metal beads inside it.
>>
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>still need to route more traces in here
sweating intensifies
>>
>>1204797
Not that guy, but the low-end PICs (10/12/16) use banked memory, which isn't particularly C-friendly. Specifically, you want to order operations and group variables so as to minimise bank switching.

The 18 series also have banked memory, but with one significant difference: indirect access isn't banked, and you have 3 sets of indirection registers. Meaning that it's reasonable to use C-style automatic variables.
>>
>>1205174
Sexy. What's that going to be?
>>
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>>1205205
rotary encoder knob to control volume, monitor brightness, and mouse sensitivity. it has an rgb led ring around it for showing % and mode. those leds were more trouble than they're worth but i think they'll look pretty neat shining up through a white PLA knob.
>>
>>1205207
How's it going to control these different things? Is there some program running on the computer that reads the knob and sets the stuff you want?
The LEDs are all controlled at once, right? Or can you adress the each at once?
What chip(s) do you use on there for logic and communication with the computer?
And where's the part that rotates?
>>
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>>1205210
the rotary encoder uses the seven central holes. the outer three are mounting. the leds are handled by the qfn40 driver ic in communication with a silabs efm microcontroller. i've used silabs' usb to uart ics before but never a microcontroller with integrated usb so that'll be an interesting experiment.
>>
>>1205112
If you determine the internal resistance of your supply you can measure the voltage drop on loads. Or, you know, voltage drop across a small resistance in series.
>>
>>1205129
Have you heard of the Socratic Method?
>>
I'm trying to find out how to charge a 450V 470uF capacitor with 9V batteries.

I feel like the easiest way is to convert the DC to AC, transform it up, then convert it back to DC.

Is there some easier way?
>>
>>1205249
No, not really, unless you want to stack ~50 batteries.
>>
>>1205249
that's one way, but a better way to do it is to charge up an inductor and then cut it off so it causes a voltage spike that you can direct through an HV diode into the capacitor. that's called a boost converter.

you can use a coupled inductor (a transformer, but in this case it stores energy) to increase the output voltage and decrease the current capability. that is called a flyback converter. you can make one yourself very easily if you can steal the ferrites out of a computer psu.
>>
>>1205249
>Is there some easier way?

for $6 you can get either an electronic bug zapper working off of 3V battery, or a flash circuit from a disposable camera working off of a 1.5V battery.
dont bother trying to DIY it coz the transformers are not easy to find.
>>
>>1205253
Thanks, that doesn't look as complicated as I thought.

What determines the output voltage though? Is it the oscillator or the inductor and how do I calculate what values I need to get my 450V? I don't want to accidentally generate >450V.

>>1205260
Meh, that'd be definitely easier. But I'd rather do it myself. I'll end up having learned something and don't have to say "except this part" when asked if I built the whole thing.
>>
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>>1205263
at very light load (>100k ESR being the only dc load really) the voltage will increase until enough current flows or a component breaks. you need a comparator to measure the output voltage and cut off the switch. or just add a load resistor, that you can roughly select by simulating your circuit with some rough parasitics. that's silly though.

you can make the high voltage sensing easier by just detecting the voltage peaks off the switch drain pin. the flyback configuration reflects some voltage back onto the switch that you can read without having to add a resistor divider on the hv side.

you can overthink these circuits all day but really everything i have in this pic is all you need if you use significantly overrated components. fyi most ucs, including arduino, have an analog comparator built in.
>>
>>1205272
I hoped to not having to use a uc for once. In your drawing, you're using a uc to control the switch, right?
Why do you have two coils in your drawing? If I understood it correctly, only one coil is used that's turned on and off quickly, not two. Or are you using the first coil's magnetic field to induce voltage in the second coil? And while you're at it, you're transforming it up by a factor of 10?
Couldn't one just transform it up by a factor of 50 and go straight from 9V to 450?
>>
>>1205285
>Or are you using the first coil's magnetic field to induce voltage in the second coil?
yes. the ratio can be whatever you'd like and you can use a single coil if that's all you've got but boost converters aren't very good at >5-10x steps. it's important to remember that the flyback configuration is still a boost converter on top of the winding multiplier. so you'll have the typical voltage increase before even considering the winding ratios. you don't have to use a uc, you just need a variable duty PWM source that can be quickly stopped by the comparator.
>>
I'm trying to look for a way to do pic related with a stereo amp for music but i can't find much info about it, should I just use a pcb?
>>
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>>1205296
Fug here it is
>>
>>1205297
you can probably just protoboard that. it's easy to throw together a pcb and you can get them made cheaply but if you've never done it before there's a lot of overhead that you probably don't want to deal with.
>>
>>1205299
It's been a pain (for stupid reasons) to make a pcb for this so I'd still like to know how to do it. I still have to get a protoboard though. I'd probably look like pic related but I don't care about the appearance as long as it sounds good.
>>
>>1205297
A E S T H E T I C
>>
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>>1205302
>>
>>1205296
>>1205297
Schematic and layout don't match. Which one you want?
>>
>>1205313
The one on the left without using a pcb, it's called dead bug or point to point I'm not sure.
>>
>>1205314
...
>>
>>1205314

your schematic is simple enough that you could make an "air pcb" just by careful planning, but you cant encase a power amp in resin coz it'll get too hot and die.
>>
>>1205305
Amplificators heat up m9
>>
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>>1204692
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>>1205368
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>>1205371
>>
next semester I'll take a circuits class. All those high order ODEs are scary
>>
>>1205378
All what high order ODEs? If it's Circuits I (basic analog shit) then the most you'll see is 2nd order.
>>
>>1205285
You can get boost converter ICs that'll do most of the work for you with a few external passives.
>>
>>1205368
Fuck the hydraulic analogy. Fuck analogies.

You don't learn physics by comparing it to other things because the analogies ALWAYS give you the wrong impression about something.

Learn the math and practice and you'll understand a concept far better than through an analogy.
>>
>>1205409
You're an idiot
>>
Sup guys, I've recently gotten access to a big uni robotics/electronics lab workshop with all sorts of cool shit. I'm more familiar with software but I'm looking to get into this.

In the past I've found that the best way to learn stuff like this is to just dive right the fuck in. What's a cool first project I could make?
>>
>>1205441

this is the holy grail of DIY projects : https://www.youtube.com/watch?v=pHi8hTvT3II
>>
>>1205446
how is that less embarrassing that an handjob?
>>
>>1205438
Nice argument. I bet you're an electrician.
>>
>>1205366
>>1205357
I was just sharing this guy's headphone amp i'm not that clueless.
>>
>>1205459
:^)
>>
>>1205357
>air pcb

What did he mean by this
>>
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I'm working on an oscilloscope that was new in 1985. It has several trimmer capacitors like pic related. It looks like you turn the piece that has three wings.

They are hard to turn so I think you need a proper tool, but all the ones I find online are like ordinary tiny screwdrivers, plus and minus.

Does anyone have experience with these and/or know where they sell the tool to adjust it? The resistor beside it is 1/4 watt I believe, to give an idea of how small the cap is.
>>
>>1205475

And I should have mentioned that the center does not have a slot or a well defined shape. It looks like a mound of solder to me.
>>
>>1205055
>learn skills at small company
>move onto larger one for advancement
>save up for uni/other courses in the process

Ahh yes zero prospects
>>
>>1205486
>save up for uni/other courses in the process
he was implying that he was lacking (or was just not interested in) higher education.
>>
Thoughts on the rigolDS1054z oscilloscope?
>>
I'm looking for a suitable microcontroller for a project I'm working on.

Has anyone here had any good/bad experience with either TI's or STM's free IDE? I want to work within a supported environment so I can get help more easily if I need it.

Also if anyone has any "high performance" MCU recommendations I'd love to hear them. Right now I'm looking at the TI Delfino and some stm32f7 dev boards. I need a fast ADC and pwm capabilities for a fast closed loop motor driving application.
>>
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>>1205519
>Thoughts on the rigolDS1054z oscilloscope?

I paid about 400 usdollars for one last month and I love it. Supposedly you can easily upgrade it for free to get twice the bandwidth and ram, but it's pretty awesome as is.

I used to think I'd hardly ever use 4 channels, and that two were fine because that's what I've used for years. Now I love 4 channels.

And this is the first digital storage scope I've ever owned. My ancient analog is fine, but being able to save images is fucking awesome.
>>
>>1205524
are you able to save data in an array or is it limited to images?

Thanks for the reply, I was thinking 4 channels would be great too
>>
>>1205519
it sucks cuz i can't afford one
>>
>>1205530

I think so. Rigol has some utilities you can pay extra for, but this guy thinks you don't need them, but it might be limited to one screenfull of data:

https://tuck1s.blog NOTSPAM spot.co.uk/2015/08/rigol-ds1054z-digital-storage-scope.html

(remove NOTSPAM)
>>
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>>1205471
>air pcb
>What did he mean by this

an ''air PCB'' is a PCB made of air, with permanent soldered connections. it should not be confused with an ''air breadboard'' where the connections are temporary.
>>
I'm trying to design a simple circuit.
Once every hour it should pull a pin high for a second or so, ad infinitum.
Now, this circuit needs to be extremely low power and as small as possible, as it will be incorporated in a watch.
Occam's razor tells me to just use an attiny, but it isn't very accurate, and still consumes quite a bit of power.
Do you guys have any better ideas?
>>
>>1205601

are u jokin' nigga?

lots of watches have a beep-on-the-hour function. just turn that on, no need to build anything.
>>
>>1205601
How important is precision in your timing? If you need good precision, go for a quartz oscillator and frequency divide with counters. If you can stand worse precision, an RC oscillator might be lower power.
>>
>>1205601
>Occam's razor tells me..
How so?
>>
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>>1205590
I dun ged it
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>>1205607
Nigga, i aint trying to beep shit.
That being said, tapping the signal for the piezo might actually work.
So thanks, now to find the smallest watch with that function.

>>1205612
It was the fastest/simplest/easiest solution i could think of at the time.
Please don't mock my very limited knowledge on electronics.
Or are you trying to argue semantics?
>>
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>>1205617
>semantics?
Of course. In contrast to rhetoric, semantics is about meaning and Ockham's razor is not about a quick, subjective hunch.
>ad infinitum
Use a free energy circuit: First battery-free cellphone makes calls by harvesting ambient power using off-the-shelf components. Details at https://phys.org/news/2017-07-battery-free-cellphone-harvesting-ambient-power.html
>>
>>1205477
>mound of solder

The slot could be under that mound of solder, maybe they fixed it in place.

>>1205521
>supported environment
kek

>>1205524
That feel when you bought the old model. Granted it was years ago but it still sucks majorly in comparison.
>>
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Will something like pic related charge up my 450V capacitor? I don't want to drive anything from it, just charge it up.

Because all other solutions I found online for charging up a 450V capacitor from a 9V source required a ton of additional stuff e.g. some sort of feedback to shut down the switch if some voltage is reached. Where's the catch here?
>>
>>1205077
I ended up buying MG chemichals' solder paste from amazon (from a trusty, non asian supplier) and flux from mouser. I'll see how it performs.

>>1205912
Yeah, you can charge a capacitor with that, but since you're cutting and letting current through the transformer instead of having a sine wave the output will be less predictable, and you might exceed the target voltage.
I built a capacitor charger based on that principle, also using inductors (vid related)
http://www.instructables.com/id/Capacitor-charger-60-400V/
Using a comparator to switch of the circuit once the target voltage is reached is recommendable, otherwise you might damage your capacitor. It's not too hard to learn about OP amps and comparators, give it a try.
https://www.youtube.com/watch?v=DdIfi3C-AiQ&t=137s
>>
>>1205912

if you replace the ''very speedy'' switch with a 555 oscillator at 100Hz, then it'll work. finding an appropriate small low-power transformer will be difficult tho, so you might be forced to use a 3V power transformer. the 555 couldnt handle that, so you'd need to add a power transistor to switch more power. and your 9V battery would then die very quickly. your circuit as is: forget it.
>>
>>1205920
>Using a comparator to switch of the circuit once the target voltage is reached is recommendable, otherwise you might damage your capacitor.

it's so much simpler to stick a zener, or a series of series zeners, across the secondary to limit the output voltage.
>>
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>>1205912
In principle that's how it works. Get a cheap disposable camera with a flash, it has all you need. There are tons of instructions on the net.
>>
I wanna buy a rail-to-rail op amp to use as buffer for some 5v stuff but I can't find a single one in my country. damn it.
>>
>>1205920
What's the comparator used for, what is it comparing? Would I use an OP amp to produce 450V and compare that with a comparator to my result on the right and cut off the capacitor in case it receives more than 450v?

>>1205924
I don't quite get the schematics here. How can the + side of C2 be connected to GND? Wouldn't that just discharge it?
I assume C1 charges and discharges pretty often in order to toggle Q1 around. But how does that work? Once S1 is pressed, C1 charges up, which enables Q1, which then discharges C1 through R1 S1 and the coil. Is that right?
>>
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>>1205942
>+ side of C2 connected to GND
What GND? There is no such, the whole thing is floating, there's only voltage differences. Define (-HV) as your GND, flip the diagram vertically et voilá, there's your accustomed representation. Look at the direction of D1 to see why (+) of C2 is connected to (-) of the battery. Tiny C1 is part of the oscillator circuit R1-Q1-T1. Here's the whole set of configurations. I picked the one that comes closest to the photo.
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>>1205942
The basic idea is to compare the capacitor voltage (or some fraction of it) to your target voltage and throttle or turn off the capacitor charger when the limit is reached.
Pic related does this using a transistor (Q1), a neon bulb (NE) and a zener diode (D2). The neon bulb can be omitted, but it doubles as a "flash ready" indicator. The strike voltage of the neon bulb and the zener diode voltage set the voltage limit.
This is a bit unusual circuit in the sense that you push S1 only momentarily and the power supply then runs until the cap is charged.
There's at least one typo in it: Q2 and Q3 should be swapped. Stuff to the right of C2 is not needed in your case.

>How can the + side of C2 be connected to GND
If you want to see the battery's negative terminal as GND, then it is a positive ground circuit. Capacitor is charged to a negative voltage in comparison to that point.
The circuit itself is a blocking oscillator and the transformer is an integral part of it.
https://en.wikipedia.org/wiki/Blocking_oscillator

Typical disposable camera capacitor chargers are unregulated and just rely on the component dimensioning and battery voltage to keep the output voltage below the capacitor's maximum voltage.

>>1205935
Okay.
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>>1205948
>neon bulb can be omitted
if you adapt the voltage of D2 and accept a somewhat longer charge time. The special characteristic of the NE2X prevents early slow pulldown of the oscillator (Z diodes are far from ideal). Pic shows the two Kodak circuits for comparison.
>>
>>1205923
not for a battery powered application it's not
>>
>>1205942
>What's the comparator used for, what is it comparing?

A comparator is just a chip that has two inputs, if input A is higher that the input B the output will be 0, if input B is higher than input A the output will be VCC. In reality the inputs are called inverting and non inverting.
You can compare two voltages, even if they're not equal in magnitude, for example, if you want to check if the voltage in your capacitors is higher than 300 volts you can connect 5 volts in one input, and a voltage divider (made with two resistors) so that when the voltage in the capacitors reaches 300 volts the voltage in the divider is 5 volts, the comparator will detect the voltage in the divider is higher than the reference voltage (5V) and will shut down the charging circuit to avoid charging the capacitors further.
The 311 is a common comparator, go watch info on it and check my instructable, it should be clear enough.

Would I use an OP amp to produce 450V and compare that with a comparator to my result on the right and cut off the capacitor in case it receives more than 450v?

No, you misunderstand what operational amplifiers do, yes, they're used to amplify voltages, but the maximum output voltage they can produce is usually 15 volts, and the output voltage will always be lower than the alimentation voltage.
Operational amplifiers have many aplications, one of them is comparing voltages. I suggest you check some videos on youtube by Dave from EEVBlog.
Operational amplifiers are indispensable for circuit making, and if you study electronics you'll see them sooner or later.
>>
How to simulate a counter using flip flops in Proteus that counts from 0 to 7 and how do I do it in practice using a breadboard?
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>>1205947
>>1205948
Thanks guys, I'm slowly getting it.

>>1206038
Okay that wasn't that complicated, I wonder why that took me so long.
So I guess something like pic related? I just cut off the capacitor and coil if I'm about to reach the 450V? Maybe with a 47K instead of 49K resistor so it turns off at about 430V.

Is there any perk in using a transformator over a simple boost converter with a single coil as seen in the second pic?

>>1206134
I don't know about Proteus, but you can just daisychain three flipflops to get an (async) binary counter. I'm pretty sure you can just grab some flipflops and do it on your breadboard as well.
>>
>>1206143
Using a transformer means you can keep the primary at low voltage. (I've made resonant converters with a 2N3904.) Your configuration requires a switch that can handle 450V.

>>1206134
How do I make an apple pie in a kitchen?
>>
>>1206143
fyi your resistors are going to dissipate over 4 watts total. use larger values. 450V^2/50kohms

you can't do this practically with a straight inductor. boost converters work by storing up inductor energy by pulling current through it with a switch to ground, and then cutting off that current path so it forces the current through the diode instead. in steady state conditions the on time (duty cycle) is what decides the output voltage. for your circuit, with a 500k load (assuming you upsize your resistor), you need your switch to be on 98% of the cycle to get a 450V output with no transformer. this means two things. one, you have higher switch and inductor current meaning you need a bigger switch and inductor (saturation is the concern here not power loss). two, you have all your current flowing into your capacitor in just 2% of the switching cycle. this will make for a very unhappy electrolytic capacitor. you can mitigate this with an output filter but that's stupid when you can just use a transformer instead.

second, i showed you the comparator on the secondary side for a reason. when you're done charging you don't want a resistor sitting there discharging your cap. also i strongly suggest reading about comparator hysteresis because when your cap's done charging the comparator will skip on and off quickly as your cap jumps between 399 and 401V (due to insulation resistance, diode leakage, and your sense resistor discharging it) and will produce some pretty ugly switching.

also what this anon said >>1206173
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>>1206177
ran out of room. instead of reading about hysteresis which can be confusing, you can instead just have a button that toggles an SR latch circuit (you can just do it with 3904s) to enable your switching, and then have the comparator toggle that latch again so it shuts off completely until you press the button again.

i perceive some frustration on your end about being pushed to include all these extra features in what you'd like to be a simple design, but they're there for a reason. if you really want bloat read about current control.
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>>1206143
>So I guess something like pic related? I just cut off the capacitor and coil if I'm about to reach the 450V? Maybe with a 47K instead of 49K resistor so it turns off at about 430V.
Yeah, the output of the comparator can go to pin 4 of the 555 timer driving the "switch".
There's one little noob mistake, if you use a 47k resistor the power dissipated will be around 4 watts, and the current flowing though that resistor at that voltage will probably make it a bit hard to charge the capacitor.
Use a 1MOhm resistor instead as the first resistor of your divider, and a 12kOhm (for example) as the second resistor. You can also add a potentiometer in series with the second resistor to fine tune the desired voltage.
Keep in mind the divider formula.
A small 10nF capacitor can be used in the output of the divider to filter noises (because the current in the divider is low and noise can occur easily from magnetic fields coming from the transformer)

>Is there any perk in using a transformator over a simple boost converter with a single coil as seen in the second pic?
I've seen both designs work well, in fact I have constructed and tested both types of capacitor chargers and they work well either way.
In my instructable I build a charger based on the principles I just explained >>1205920
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>>1206038
Your text is riddled with misconceptions. A comparator is essentially a 'truncated' opamp (see pic). Both compare the levels at their respective inputs. An opamp does not 'amplify voltage' it can amplify a _signal_ with a definable gain. A comparator cannot do that because it is inherently unstable, by design, but it still amplifies its input signal to switch (!) its output. Without external feedback an opamp acts as a comparator.

Look at the Kodak max circuit above. No opamp, no comparator. But it realizes a comparator function (!) that shuts down the generator when the capacitor is fully charged. How does it do that? What does it compare to what? I'd say get rid of this obsession with specific components, learn to understand circuits at the functional level.

Moral of the story: Knowing the name of X doesn't mean to know X.

>>1206143
>something like pic
Something like that, but not as drawn. If it works at all it will be a very, very 'sparky' affair. Where does this nonsense come from that you need to switch off the capacitor and the primary of the transformer? Wouldn't it be enough to simply stop (open) the 'very speedy' switch for the same result? Also, no one in his right mind would ever connect a comparator input directly to the supply voltage which isn't even within the specified limits. That thing only needs an input difference (!) of a few millivolts to switch its output. Normally you would use something like a Z diode (e.g. 3V3 or less) as a reference and divide the high voltage much further down. Your current values of the divider load the hv output with about 10mA, and 10mA*450V=4.5W, wasted. A typical 9V battery cannot even supply that power.

And on that note, good midnight. I wish you all a steep learning curve and lots of fun with your high voltage experiments. May the spark be with you.
>>
>>1206204
literalism is extremely unconstructive here. in the first half of your post you're explaining things with this revelatory tone that everyone but the new guy already knows, and that the new guy will just be very confused by.
>>
im looking for books generally relating to the electronics of guitar pedal and amplifiers, can anyone recommend one?
>>
>>1206214
Pretty much the two basic courses of EE are amplifiers from the ground up. I could recommend a book but it's an actual book. Guitar pedals and amplifiers are very basic.
>>
>>1205524
Thank you, I've been needing to get an oscilloscope and I that one looks nice.

Have you looked into other 4-channel oscopes? I'd only be working with signals under 2MHz, so I wouldn't need like a 500MHz scope. I'm mainly looking at saving the data. I have a single-channel scope that can, but it was super cheap and you have to retrieve the data with a terminal over a serial connection. The device actually has a live USB mode, but they never made the software nor released a spec... I'm serious and it pisses me off.

In theory though, I could use a dumb listener and decipher it myself couldn't I? Decisions decisions.
>>
>>1205475
I have an oscope that's probably 70s, and it didn't need recalibration as it had fine adjustment knobs on the front, all I might be able to do is increase the focus voltage. What kind of scope is it? Mine's a Heath 4554
>>
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>>1206233
I think I'm going to get a DS203: 8MHz, CSV and images support, 4-channel, has upgradeable firmware, and is portable for less than $200. <3
>>
>>1206257
i'd strongly suggest you reconsider. 8MHz is less than you think. for example if you're looking at a power switch waveform at 100khz you don't just need 100khz bandwidth, you need to capture the peaking and ringing which can go well into the mhz. you're paying half the price for 1/10th the bandwidth of a hacked rigol. you should just save up imo.
>>
>>1206225
Yeah, whch book would you recommend?
>>
Is there some equation that will tell me how much voltage and current I need to pump into an antenna to get out a certain amount of RF power? Like if I want 100W for instance.
>>
>>1206331
i'm not an rf guy so defer to anyone else that replies, but antennas are typically 50 ohms at their intended frequency. sqrt(100W*50 ohms)=~71Vrms.
>>
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>>1206173
>>1206177
>>1206182
>>1206204

Man, you guys are really awesome. I'll try to summarize all your information.
1. I'd rather stay with the transformer design.
2. I need to beef up my resistors.
3. Comparator hysteresis. That's just the comparator flickering back and forth, right? I feel like I can fix this by doing something like in my pic.
4. Add a filtering capacitor to the voltage divider.

>Yeah, the output of the comparator can go to pin 4 of the 555 timer driving the "switch".
Can't I just use an oscillator with a fixed frequency to toggle the switch and call it a day?

>i perceive some frustration on your end about being pushed to include all these extra features
It's a bit overwhelming at first, but I see where all this is coming from. As long as I actually understand what's going on, I'll include them if necessary.

>Where does this nonsense come from that you need to switch off the capacitor and the primary of the transformer?
Well, turning off the first coil once the capacitor is charged makes sense as I don't want to waste energy by keeping the left side on. Turning off the right side should prevent the capacitor from dischargeing through the resistors.


Let's take a look at my drawing. If I'm not mistaken, the following will occur once I put 9V on the left side: We don't have any voltage on the right, so the bottom left and top right transistors are pulled high. Now, the capacitor starts charging. As long as we are below 450V, the comparator outputs HIGH, the pnp transistor doesn't close, the switches are still pulled high. Once we reach 450V, the comparator outputs LOW, the pnp closes, grounds itself and both switches. As the switches close, there's no voltage induced on the right side. Also, the capacitor is cut off of the comparator, so the comparator receives 0V on the - side. Now it outputs HIGH again, but this time, the switches still stay open as the pnp is still grounded.
>>
>>1206336
The only thing I feel is missing around the comparator is a resistor that prevents a short from its HIGH output to GND and some switch to cut off the pnp from GND to be able to set the whole thing into motion in the first place.


A few questions:

But does reaching 450V on the right side mean that my capacitor is already full?

Also, shouldn't I use a 1M and a 21K resistor as that'd result in about 9V at 438V?

What's the problem with connecting straight 9V to the comparator?
>>
>>1206337
>>1206336
>1
yes, generally you want to leave a margin on capacitors. you can still charge a 450v cap to 450v, you'll just shorten its operational lifespan significantly. for hv power caps a 20% margin can be fine. for low voltage caps 100% or more is preferred.
>2, 3
modern comparators and amplifiers can interpret inputs up to their supply voltage. some older models can only work with inputs up to a few volts less than their supply. if you're feeding the comparator 9V and it's powered from 9V, it won't be able to tell the difference between your 9V noninverting input and a 10V inverting input. in reality it might be fine but that sort of operation is outside the datasheet and can either result in funny outputs or smoke. you'll want to divide down the input through some high value resistors to ~5V and then compare to that.
>other
understand that the winding directions on coupled coils matter. see pic related. also you want to connect the secondary winding as shown to your primary ground, don't leave it floating. it'll generate a bunch of noise for no reason. if you do want to leave it isolated, replace the direct connection with a capacitor with a Y safety rating.

i didn't look that close at it but i don't believe your comparator latching idea will work. hopefully one of the other anons will get more in detail. i'd also suggest that instead of having another power FET on the primary side you instead just cut off the pwm circuit. that'll save you some power losses and cost. for a one off hobby project it's not like it really matters, but it's good practice.
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>>1206344
>see pic related
>doesn't post pic related
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>>1206331
This can be a complicated subject. 100W total, or in a certain direction? And generally your antenna will not be a perfect match, which you have some ability to make up for.
>>
What's everyone's favorite free pcb design software?
>>
>>1206421
KiCAD
>>
>>1206421
Altium

:^)
>>
So, I was heating up a small 1 dollar calculator PCB hoping to remove the COB epoxy from it (I looked it up after failure) but I just want to know if it was unwise to have breathed in the smell it came out after having my heatgun on the PCB for a minute. Of course I did not breath in after I smelled it, but how hazardous is that?

I'm very scared at the moment.
>>
>>1206438
You're gonna die. In 50-60 years.
>>
>>1206442
Anon PLS!

I wonder if it was just the heatgun's smell though, cause the pcb did not fume.
>>
>>1206422
Anybody have a tutorial/guide for KiCAD 4 for macOS? It looks pretty different to the Windows one I see all the YT vids of.
>>
How do you guys power up your 12v stepper motors? Looking for a cheap and ez way. Currently using 12v 2amp transformers from old household machines.
>>
>>1206421
Circuitmaker.
>>
>>1206421
Altium no doubt about it
>>
>>1206438
It's quite unlikely to accidentally produce some gas so toxic to seriously harm you with a single sniff (and in that case, you would notice something is wrong).

Whatever substance can be produced by burning an old PBC, is generally something that kills you only after repeated prolonged expositions over a time span of a few years.
>>
>>1206421
orCAD Capture/PCB Editor

It's not free though, at least not unless you pirate it that is.
>>
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Rollin
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>>1206719
>Rollin
>19 . turning signal FSM

WTF is that? a finite-state-machine?
- no buttons pressed: do nothing
- right button pressed: right light lights
- left button pressed: left light lights
>>
>>1206719
rolling
>>
>>1206743
probably mean traffic light
>>
>>1206743
Yea I'm not doing that. I looked at the other suggestions for rolls around 19 and just didn't reroll.

>>1206719
Now reroll
>>
>>1206775
>cellphone detector
Im actually in school for antenna engineering atm so this could be fun
>>
How do i turn a +-10V signal to a +- 80mV signal that has a DC offset of 1 or 2 volts? I only have access to a 5V rail for supplying an opamp.
>>
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>>1206780
>>
>>1206785
Note that this assumes you don't care about DC on the input.
>>
>>1206789
yeah for some reason i assumed he meant ac
>>
Anyone have any experience with amplifying the output of a strain gauge wheatstone bridge? Or more generally any tips on circuit design for amplifying wheatstone bridge output?

my mcu has a proper adc so I just need to amplify the signal.
>>
>>1206879
I did some research and It seems I need to make an instrumentation amplifier.

Anyone have tips?
>>
>>1207028

dont make one of individual op-amps, but buy a ready made unit like the INA131, coz it's easy for a noob to screw up the design with individual parts. search digikey for diff models if you find this one too expensive.
>>
>>1207037
>INA131,

out of stock at digikey

mouser has 231 at $9.36 for one

The gain is set at 100.
>>
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What's the "proper" way to connect a wire to a terminal like this? Do you just strip it and plug it in, or is it better to put some flat spade terminal on it? Cables sometimes slip out over time when I simply screw them in.
>>
>>1207059

If the wire is stranded, you should at least twist it firmly. Even better to tin it with solder.

If the wire is solid or stranded and is way to small you can fold it over on itself one or more times. Or, strip a long length and wrap it around the insulated part to make it nice and fat.

And always tighten securely. That requires experience to know how tight you can go without stripping the screw head or threads.

There's no crimp terminal that I'm aware of that's designed to fit inside that terminal.
>>
>>1207074
>There's no crimp terminal that I'm aware of that's designed to fit inside that terminal.

Pic related is exactly that. They're called (crimp) ferrules.
>>
>>1207074
>Even better to tin it with solder.
please leave right now
>>
>>1207074
>Even better to tin it with solder.
No thanks, solder is too soft to reliably clamp. 99/100 there will be no problem, Eventually it will bite you especially with current heating.
Fold a single core if necessary, bootlace ferrule for stranded ideally.
>>
>>1207109
>>1207116
>>1207118

wow was I wrong. thanks for the information.

and I can't leave or I won't keep learning (and passing out bad tips).
>>
Anyone care to share experiences with chinkshit gate programmable gatorades
>>
>>1207217
Sorry
Field programmable gatorades
>>
>>1207037
>>1207043
thank you, I'm looking through TI's instrumentation amplifiers now.
>>
>>1207217
i like the lemonade flavored gate arrays the most
>>
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>>1205215
>but never a microcontroller with integrated usb so that'll be an interesting experiment.
It's fun and I recommend it to everyone. I haven't programmed SiLabs USB controllers but I'd suggest ATMEGA-U processors just because the LUFA framework is teh secks and 8051 gives me a headache.

>>1206421
KiCad 4 is bretty gud. I used to be all about Eagle when I had a key but not after Autodesk ate them.

>>1206504
Thanks to the LED revolution, 12V 10A switchers can be gotten for under $10. Search AliExpress and be amaze.

>>1206743
>19 . turning signal FSM
Hard mode: https://www.youtube.com/watch?v=jIjY7mERBrw
>>
>>1206785
Real fucking neato.
So this would work without the cap and the 10k resistor?


>>1206879
HX711 is a 24bit adc just for strain gauges, might be good for you
>>
>>1207292

if you remove the cap, then the resistance of the voltage source will affect the voltage divider ratio, so you have to recalculate everything. the leftmost 10K is nice to have otherwise the 1M will very slowly charge the 1uF so you get weirdness when you turn the unit on.
>>
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>>1207292
It can be simplified to three resistors. The cap can be dropped if you care about the DC component of your input, if you don't leaving it in would probably be better.

If you want control over your gain and offset can replace the top and bottom resistors with a single 5k trimpot and the left one with 200k trimpot (or 100k + a ~100k fixed resistor)
>>
>>1207292
I didn't realize you could plug a full bridge setup into the hx711, Thanks.

I'll consider it as an option but I'm inclined to use an adjustable instrumentation amplifier so that I can adjust my gain more easily.

I'm inclined to just amplify the raw signal so I can use the onboard adc on my mcu and be done with it.
>>
>>1207349
the hx711 has a PGA built in that can be multiplied with your static inst amp gain.

another ic option is the nau7802
>>
>>1206421
sketchup...
>>
>>1207217
My mom only buys me chinky powerade logic devices
>>
>>1207379
weirdo
>>
>>1207395
I just can't be fucked learning anything else. I downloaded KiCad, stared blankly at a screen for an hour, stared blankly at youtube tutorials for another hour, and never opened it again. It's good enough for what I'm doing, because I don't have to run any traces from IC to IC, just to and from wires that lead to switches and LEDs on the faceplate.

Also sketchup doesn't let me go small enough, so I do it all at 10x scale, maybe 100x if I want super detail.
>>
>>1207410
i don't know about kicad but while i found altium to be a huge pain in the ass to learn and i wanted to kill myself for the first few hours, i now realize just how useful all the annoying overhead in a pcb editor is. i'd recommend trying again. also download altium desu baka.
>>
>>1207410
>>1207412
All layout tools suck, basically, some more than others. We have Mentor Expedition at work and it's ridiculously complicated. For home use I like KiCAD.
>>
>>1207412
>download altium
Pretty sure it's Windows only, one of the big problems I've encountered is that the macOS version of KiCAD has a different UI from the Windows version, unless KiCAD 4 has had an overhaul in the last year or so.
>>
just got my ESP8266-01 today. What firmware should I use? I'm planning to install a small webserver on it to control an electronic door
>>
>>1207379
kek
>>
>>1207329
>>1207330
Thanks for clearing that up.
>>
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Alright, after much deliberation I realised that nothing beats the simplicity of this design for a switch debouncer, and it means I don't have to go out into the cold and buy parts.

But I have to be able to charge the capacitor up with the first voltage spike, meaning the resistance to the capacitor must be very small, and having the capacitance small is also important. But I also need a decently large R*C, which would be easy if I didn't need a substantially small resistor to pull the button output to ground when it's not being pushed.

So can I just use a 10MΩ resistor to bleed the cap and pull the button output to ground when it isn't depressed? My other question is what sort of timeframe should I expect switch bouncing to occur, so I can plan my R*C around that? I probably want a maximum R*C of 0.2-0.4 so I can spam the button a few times a second.
>>
>>1207494
This has been explained to you many, many times already. Since you don't want to listen, why don't you just try it? Maybe you're happy with the results.
>>
>>1207494
just use 10nF 1M. have a 1uF on the high side to decrease the charge current loop if you care at all about that.
>>
Hey newfag here. How does one approach making a PCB? What are the steps involved.
I understand it currently as:
>1.Design software/paper sketch of the board >2. Create the basic board with chems/ordering
>3. Order parts and solder them on.
How much does it approximately cost money and time to build for an example: an 50W stereo amp?
>>
>>1207642
You might want to consider using veroboard instead.

A really old-fashioned way to make a single PCB would be to use etch resistant tape or ink directly on PCB material and etch it. Pretty much no-one bothers with that anymore and instead uses some suitable CAD program. You can then either send the files to a PCB house, or print the design on paper or transparency and etch it by yourself. One method: http://www.instructables.com/id/PCB-making-guide/
>>
>>1205521
I have used a cc3200, and a friend of mine has to program some other TI chip during his doctorate a year or two ago. Our experience are roughly the same: we went in confident from our previous experiences using TI motor drivers, power ICs and other non programmable chips, but we're astonished by the absolutely ghastly documentation, support, and generally complete lack of clearness and usefulness of the provided examples. My understanding is that most 32bit uC are that way, although I have heard good things about Nordic and STM, with which I have no experience.
Another friend used an f4 of f7 from STM and quite liked it, but only without using the official programmer/debugger. Google things well and look for active communities, as support for hobbyists, and generally people unwilling to pay for a support or integration engineer may be completely inexistant!
>>
>>1207500
There's objectively nothing wrong with this design for my application, as I only need a quick rising edge. The previous circuit shown had the exponential curve at the rising edge, not the falling edge, which is why it didn't work. But after messing about with flip-flops and comparators, I realised that I was overcomplicating it, leading me back to this model. But if you or anyone else knows where to get a few cases of switch bouncing waveforms that would be really helpful since I don't have a scope of my own.
>>
>>1207109
Holy fuck I had no idea what these were even called, I've got some in my crimp box but just assumed that they are for making removable joins.

I've been doing it all wrong for years then.
>>
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Anyone know how to correctly charge these types of rechargeable AA alkaline batteries? An internet search brings up a Wikipedia page which sounds more like marketing than actual technical information.

It came out of an old solar light and I'm just charging it manually by sending 200mA DC through it, but I don't really know if that is correct or when to terminate charging.
>>
>>1207819
From the very limited information I've seen, best is pulsed, with pretty low average current. And don't expect them to last long no matter what you do.
>>
>>1207831
Hmm maybe I'll put it through a 555 timer+fet then to pulse it, how come they don't last long and is that the reason why rechargeable alkalines are not more common?
>>
>>1207839
The chemistry doesn't work that nicely in reverse, so capacity drops pretty quickly each time it's recharged.

NiMH is usually the better option unless you really need the bit higher voltage of alkaline.
>>
>>1207780
some switch datasheets list maximum bounce time. i haven't seen one above ~20ms but then again i haven't gone and surveyed them.
>>
>>1206265
I went and bought one, I'll tell you how it goes. I still have a 40MHz analog scope.

Also had to get a new damn capacitor/inductor checker because I burnt out my last one.
>>
>>1207845
Just to reiterate they are branded as rechargeable alkalines, but would that not matter and the capacity would still get smaller with each cycle?

I don't need them for anything in particular since they were pulled out of an old solar light, I'm just testing them to see if they are any good since I don't like holding onto useless items.
>>
>>1207848
Yep, capacity still drops off quick on the rechargeable alkalines (although nowhere near as fast as attempting to recharge regular alkalines)
>>
>>1207847
40MHz analogue scope is a a much more useful instrument than a dso nano IMO.
>>
>>1207819

rechargeable alkalines require a quite special charger. you can certainly charge them the way you're doing it, but the chances of them leaking go way way up. if you get that special charger, you'll find they'll also charge normal alkalines if they're high quality ones like Duracell and Energizer. these are good for 2-3 charges before they start to leak and ruin your charger or the gadget you're powering.
>>
>>1207642
Ordering 2-layer PCBs costs roughly 0-$2 per square inch, depending on where you order it from. 10cm by 10cm from China is dirt cheap.

If you've never done it before, then it will take a while. It also depends on the complexity. For something like a class A JLH, it's simple and the biggest costs will be transistors and heatsinks and power stuff. For a class AB then that's probably too much complexity for a first project.
>>
>>1207849
Thanks for the advice. My first test is to see if they even hold their charge for more than a few days, I've gotten rid of so many NIMH types that drop to under a volt just days after coming off the charger. Others will experience a large voltage drop with a load of just a few mA.

>>1207854
Thanks, I'll certainly look into them for getting some more cycles out of regular alkalines but considering these ones came out of a Chinese garden solar light they are probably not the best quality anyway.

Fun fact: I had to bang on them with a screwdriver handle to even get them to accept a charge, before that they would draw a few uA at most even with the power supply voltage cranked all the way up (with a resistor in series of course).
>>
What cut off voltage should I choose for one of these under load? I hear people say under 12v is flat but really there is still lots of energy left in the battery at this point, would 11.8v be an of cut off voltage to use at a 20 hour discharge rate?

I want to balance between usable capacity and life span of the battery by not discharging too deep.
>>
>>1207870
>12V nominal battery
>"12V is flat"

The fuck? I guess if that's open-circuit, but, under load, I'd expect the cutoff to be at 10.5-11V.
>>
>>1207887
Yeah there is a lot of misinformation going around with these, probably started in the automotive field. For example at 0:55 this guy thinks the low voltage cutoff point should be 12.1v-12.2v under load!

https://www.youtube.com/watch?v=1BKEMDYAGBA

My battery is rated at 7ah with a 20 hour rate, this gives a discharge current of 350mA and takes it down to 10.5v but I think that's too low for constant cycling.

Should I go with 11.8v or something a little bit lower? I just don't want to fuck the cells too early with constant deep discharge.
>>
>>1207819
Update: They have been off charge for a few hours and one of them is holding at 1.7v whilst the other has dropped to 0.6v, banging on the casing brings it back up again until its left alone for a while.

I think its falling apart internally or perhaps there are whiskers forming and shorting the cell out.
>>
>>1207891

If that's actually your battery, this is the datasheet.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0ahUKEwia3LGWpIPVAhVF2oMKHW1XA6AQFgg_MAI&url=http%3A%2F%2Fwww.yuasa.co.uk%2Fyuasa%2Fdatasheet%2Findex%2Fsku%2FNP7-12%2F&usg=AFQjCNELdtxvaQlLIZ9tAmjubVZhesRUTg&cad=rja

According to that, 10.8V is dead, at the 10hr rate. Given that, I'm going to make the assumption that 11.25-11.5V would be a good compromise between longevity and usable capacity.

...no guarantee is expressed or implied.
>>
>>1207916
>>1207891
>>1207870
>>1207887

Also, just FYI, the actual cutoff voltages for charge/discharge will vary depending on the exact makeup of the electrodes and the electrolyte. For that matter, so does every other performance aspect of a given battery, even within similar chemistries (which probably will not be denoted exactly, and just listed under the more generic "lead acid", "lithium polymer", etc.).


The ONLY way to get reliable number is to find the datasheet. Otherwise, the best you're doing is making an educated guess.
>>
>>1207780
>objectively nothing wrong
Your shift register is not a mind reader. It does not know that your long, slow fall is supposed to count only as a one single falling edge, not a falling edge + random noise.
Besides, there are no guarantees that even your rising edge will be good. This has been explained to you already.
Just build it already, maybe you're happy with it.
>>
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I need help /ohm/. I'm trying to fix my vaporiser, it appears that a component on the board (see pic) has cracked off its solder joints. All I can tell you is that it is a tiny, black rectangle with three legs and '431' printed on the top. Three questions. What is this? Where can I get a replacement? And how the fuck do I solder something so small?
>>
>>1207780
Ok, it didn't work with the lowest value capacitors(electrolytics unfortunately) I had lying about, even with a stupidly high value resistor. It's not like I didn't see this coming, but now that it seems that I'll have to buy parts, I might as well go for the Schmitt trigger method, unless the NOR/NAND RS latch method is better. What sort of caps should I be using with the improved design, now that I'm going to be buying them anyway?

>>1207924
>a falling edge + random noise
This is likely what happened, and if the ESR of the capacitor was too high then I imagine that would mess with my rising edge too. I don't suppose there's an easy way of measuring capacitor ESR without a scope, is there? I could try to make myself an NPN-logic RS latch and see if that works to debounce the button, because it should at least make the falling edge as good as the rising edge, and eliminate the problem of capacitor ESR. If I keep R*C = 0.05 I should be fine. Thanks for the help.
>>
>>1207929
That's a tiny SMD component. By googling "431 SMD" I get the LM431, an adjustable zener diode:
http://www.ti.com/lit/ds/symlink/lm431.pdf
If you don't have the patience or the skill to solder SMD, your best shout is buying it in a TO-92 package (like a common transistor) and fixing it in there on the tiny solder pads, and securing it with a dob of epoxy/silicone/silastic once you're sure it works.

You can buy 20 of the TO-92 LM431s for $3.60 with free shipping from AliExpress (they don't sell the SOT-23s anyways), or anything between 50c and $1 plus shipping each from Digi-Key.

I've never tried soldering SMD, but I wouldn't advise trying to solder another tiny SOT-23 on there, at least not without some degree of experience and decent equipment.
>>
>>1207932
It blows my mind how much experience and knowledge is on this general. Thanks heaps anon, I have a soldering iron but I think I'll butcher a replacement component so I'll check out the other one.
>>
>>1207932
Also, is this one that I am looking for?

https://m.aliexpress.com/s/item/32707206181.html?spm=a2g0n.search-cache.0.0.70bc08b9KcbSyH#autostay
>>
>>1207935
Yes, though there is a cheaper one. Before going down that route make sure you've got room for the component to fit inside the housing, you don't want to have to cut a hole in your electric mouth chimney.
>>
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>tfw too scared of electricity to wire up my new cooker.
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>>1207891
>misinformation
Sorry to tell ya buddy, lead acids degrade super fucking quick the deeper discharge you go. Automotive they don't recommend under around 50% deepest discharge, because your battery might last a year doing that once a day. 20-30% makes it last twice as many discharges, and the less the better, which is why a lot of supplies are built stupendously overcapacity, because deep discharging beats the shit out of em. It's not as bad with other kinds, but all batteries are affected by it. And of course being too energized is a problem the higher energy density the battery is.
>>
>>1207960
Well would 11.8v be an ok cutoff point under load? I would at least like to consume half of the energy stored in my little 7ah battery.

The 12.2v the guy in the video mentioned still seems quite early.
>>
>>1207962
11.8 probably won't hurt it. You could still probably get a fair amount of cycles t 11V, but below that would probably be bad.

Don't forget, current draw can result in overheating too, so "under load" can mean a lot of different things
>>
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>>1207929
20 / 99 cents
(must be willing to wait a couple of weeks on shipping)

http://www.ebay.com/itm/231787647164
>>
>>1204692
Hi guys, beginner here, and I had a question about materials we should start with. Is there a general consensus on what materials we should have in our toolboxes, or would you say it's best to buy things as I need them?
>>
>>1207932
While that chip might be functionally identical to LM431, that datasheet of yours says the marking of a real LM431 is N1*, not 431 (or A31). Same with TI's TL431 and a couple of other related chips I checked.
>>
>>1208045
PZM4.3NB1 zener diode from NXP, obsolete as fuck, replacement part BZX84-B4V3.
>>
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Can anyone tell me why Kirkhoff's Voltage Law for this circuit can be written as q/c + I*R + L*dI/dt = 0, rather than q/c - L*dI/dt - IR, with S2 closed?

I assumed that VR and VL are in the same direction as VC, and the current flows clockwise.
>>
>>1208181
Figured it out. It only works if you assume the current is counterclockwise, L+ is on S2, and R+ is on L-.

Follow up question:

Why the fuck would you ever analyze a circuit like that after the capacitor is charged to a positive voltage? A middle schooler would know that the current is the other direction.
>>
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>>1208197
>Why the fuck would you ever analyze a circuit like that after the capacitor is charged to a positive voltage? A middle schooler would know that the current is the other direction.


wut. you leave fucking middle schoolers out of this fool.
>>
>>1208200
i want to fuck a middle schooler
>>
>>1208181
Defining positive voltage as toward the top left point is just as valid as defining positive voltage clockwise. If sign mattered it should've been indicated in the schematic.
>>
>>1208296
It did, and it wasn't. I'm going to write my professor a few meek words along with the submission.
>>
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What's the total resistance of this circuit? The resistor in parallel with the short is confusing me. There was a voltage source there but I shorted that to determine the Thevenin resistance.
>>
>>1208045
>of a real LM431
Yeah, well fat chance they'd use a TI part on a Chinese steam flute anyways. But will replacing it with a different one make much of a difference?

>>1208297
Don't be a prick, a positive voltage clockwise is a negative voltage anticlockwise, so this result is valid. It's there to force you to think a little differently about the answer, not to write a complaint.
>>
>>1208302
consider the short to be zero ohms. the parallel equivalent of the short and the 2.7k is thus zero ohms. you can add that zero ohms in series with the top 1.2k so that you then have two 1.2k resistors to ground in parallel. that makes 600 ohms.
>>
>>1208302
Since the 2.7kΩ resistor is being shorted across you can ignore it, so the result is just 2 1.2kΩ resistors in parallel, or 600Ω. Looking at things it seems the 2.7kΩ resistor won't effect the final equivalent in the slightest.
>>
>>1208302
>2 squiggle resistors
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>>1208310
some people just want to watch the world burn
>>
>>1208310
that's how you draw resistors with less than 10000 ohmage
>>
>>1208313
Maybe in commie land
>>
>>1208305
>>1208306
Thanks guys. I'll dedicate my perfect prelab score to you
>>
>>1208303
Both results are valid. Your notation shouldn't have any effect at all on whether your answer is correct.

I used my original equation to get the damped harmonic equation and guess what, it comes out the same way. This intermediate one just fucks you if you set your problem up in a different, more intuitive, and equally valid way.
>>
I still don't know what air pcb means
>>
>>1208344
if you compress air enough it turns into a nitrogen slush that can be laminated in a deep freeze chamber. if you etch it with gallium you get a substrate with excellent rf characteristics. it's only useful in particle science, but its nickname is an "air pcb". they're actually made with lab grade nitrogen though since air is retarded.
>>
>>1208348
are u meeming me >>1205590
>>
>>1208350
no i was being completely serious
>>
>>1208352
I don't wanna use a pcb of any type.
>>
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I want to do pic related what are the pros and cons? what makes for a bad design? what's parasitic capacitance? how close should I solder the components together?
>>
>>1208364
oh my god stop
>>
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>>1208365
I'll gladly accept answers or a google link
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>>1208365
What a piece of shit, you can't even tell me where to fuck off? I guess I'll have to Do It Myself.
>>
>>1208344
Serious answer: it's when you wire components together without the use of any surface to mount the components to. A pcb in the air if you will.
>>
>>1208389
OK, I'll probably use wire too but what gauge would be fine? if you can be arsed to answer that.
>>
>>1208392
I'm hardly a electrical engineer, but it really depends on what you're doing. The higher the gauge, the more you can get away with, but for most applications that don't involve high amperage's (House mains amounts) smaller gauge wire doesn't change much.
>>
>>1208403
Ok thanks.
>>
>>1208403
thicker wire is also stiffer, can be useful if you're trying to hang components in the air.
>>
>>1208366
this is like some kind of "ground plane" meme

>>1208364
you can do freeform circuits nicely, theyre an art.

You probably arnt dealing with anything too sensitive or ultra high frequency or anything so just make it look good and you're set.

If you're trying to actually prototype something and not have to worry about it being ultra delicate and liable to short if you brush your hand against it, then use some through hole protoboard, preferably the double sided green type.
>>
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I'm trying to come up with a transfer function for the following circuit in the form Vo/Vi. Is what I have correct? I looked at some other examples and they were finding the Thevenin equivalent, short circuiting the capacitor, etc.
>>
>>1208430
>commie resistors again
>>
>>1207109
So that's what that funky crimping die is for. I had no idea there was a real electronic use for it. TIL.

>>1207891
That guy's right, for automotive purposes. A mechanic once bricked my ECU by trying to reflash it with a marginal battery. 1.8V/cell is considered empty in general for lead-acid chemistries but your 11.8V is a good safety margin.

>>1207930
1nF/100kohm should do it. Go Schmitt trigger, they were made for this sort of thing.
>ESR
You're way overthinking it.

>>1208041
It never hurts to have a full range of resistors and ceramic caps around in case you need to change something in a design at the last minute, and maybe a few various transistors, AVRs and maybe op-amps to feed any sudden larks, but beyond that, you're better off building stock up over time based on your interests [spoiler]or what's on super sale at AliExpress[/spoiler].
>>
>>1208436
>>ESR
>You're way overthinking it.
How the hell else would my rising edge get messed up? The only reason I can think of is that the initial pulse/bounce isn't long enough to charge the capacitor up to a definite logical high. I don't have a scope so I'm just speculating, but this must be caused by the charging R*C being too high for the given timeframe. But I'll do another test to see if I'm getting messed up on the rising or the falling edges.

Looks like I can build a Schmitt trigger from only 2 BJTs, so I might give that ago unless the storm lets up.
>>
>>1208451
>How the hell else would my rising edge get messed up
Bounc-
Okay, maybe it is ESR then. It could conceivably be the current spike on the supply too, depending on the size of that cap.
>Looks like I can build a Schmitt trigger from only 2 BJTs, so I might give that ago unless the storm lets up.
That's a really good idea famm. It'll be much better i.e. properly behaved with hysteresis.
>>
>>1204714
>tfw wrote my own custom assembler/simple compiler in Lisp

Made life a LOT easier. You too can do it, here's a simple article detailing how it's done:

http://ahefner.livejournal.com/20528.html
>>
>>1208430
If this is AC analysis, Z_C = j*omega*C.
>>
>>1208303
>But will replacing it with a different one make much of a difference?
Some variants have different current and voltage ratings.
The point was that assuming it to be in any way compatible with TL431 simply because it says 431 on top isn't justified, as the device markings on SOT-23s usually have nothing to do with the real type number. Some other verification is needed.
>>
>>1208496
I thought Zc was 1/jwC
>>
>>1208495
>Made life a LOT easier

WTF dude, you needed to write a program to perform a certain task, but instead of doing that...
- you created your own programming language syntax
- then wrote a compiler to compile that language
- then wrote the program to perform the required task in the new language
- then compiled it and ran it
- and it was EASIER that way?
>>
>>1208466
>It could conceivably be the current spike on the supply too
First my ESR was too high and now it's too low? I hate this area between analogue and digital.

But by the looks of things it's the falling edge that messes me up, but not with any sort of consistency. Which is to be expected since I'm holding the voltage in the 1-4V intermediate range for a significant time period.

>>1208497
>device markings on SOT-23s usually have nothing to do with the real type number
I was afraid of that, I hate SMDs for being so obscure. So unless there's an easy way to test the thing (there probably is desu), best bet is to retrace the circuit and see if it makes sense. Unless he already bought the part(s), in which case he'll be 1 month and $4 angrier.

>>1208498
You mean Z_C = 1/(J*w*C).
>>
>>1208504
The "compiler" is just a bunch of functions that concatenate code onto a byte array. A program is just a sequence of function calls like (add 5 'A) and (nop) that encode the operation and its arguments as an opcode and then adds it to the output. Using the architecture's reference material, you can write this simple tool in any modern language. The difficulty is proportional to the complexity of the architecture.

If the thing is simple and has no existing toolchain it can be a definitive improvement over proprietary assemblers. It's easier to integrate with higher level languages like Python. I gave Lisp for example because it's easy to make some simple control flow functions (like if and while) that become a sequence of assembler function calls, which append machine code to the output vector that will become the program.

If there's a C compiler I will definitely use it
>>
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I'm trying to switch with single pin between two sensors, is current schematic ok or should I use two N mosfets with inverter on one?
>>
>>1208498
Right. Getting rusty.
>>
>>1208313
>ohmage
>here we go again
>*sigh
>>
>>1208545

what's your problem. everyone in my lab says ohmage, faradage, henryage, etc.

You just get used to it after a few weekages of hearing it.
>>
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>>1208512
I made some tests out of curiosity. I used >>1207494's circuit with 1.5n capacitor, 10M (scope probe) pull-down resistor (resulting in 15ms time constant) and some Tyco's snap action switch. Pic related, 3 button presses. Of these, the green curve was the most typical, maybe 3 out of 4 presses. The heavy ringing is a result of rather long (uncut) capacitor leads.

>I hate SMDs for being so obscure.
Yeah. There are device marking tables, like http://caxapa.ru/thumbs/588912/smd-codes.pdf, but they're incomplete and full of duplicates.
Anyway, at least "U2" suggest it's an IC and all the 3 pins seem to be connected. It wouldn't be a huge surprise if it actually was compatible with TL431.

>>1208520
Why did you bother with such trash-tier processor to begin with?
>>
>>1208547
It was cheap

The poster above probably bought cheap ass processors for the same reason...
>>
>>1208197
The direction of edges is entirely arbitrary. It doesn't matter which direction you choose; using the other direction will just change the sign.
>>
>>1208521
some mosfets won't be fully turned on at 3v, beware. the situation will get even worse at low values of the pfet resistor because your gate-source voltage will drop down to 2v or less which won't turn that many mosfets on. better to just have two nfets, one with an inverter, and check your datasheet to be sure you can drive them at 3v.
>>
>>1208504
Making a compiler isn't that hard anon.
>>1208495
>lisp
</3 but tahnks anon
>>
>>1208629
You can use any high level language like Python. Just make a global list of bytes, functions that add encoded instructions to that list, then make programs by calling those functions from within Python.

Symbols, labels and stuff complicate the assembler a bit but not by much.
>>
In the context of filers:
What the fuck are poles and zeros?

I get that when your filter has more poles it has a higher roll-off. I think it's -6dB/octave per pole or something like that but I still don't really understand what a "pole" is... nor do I understand what a zero is, I think it affects phase response or something but I'm not really sure. To me it just kinds of looks like mathemagical nonsense.
>>
Recently I decided to learn to make my own PCBs, holy fuck how have I not done this sooner, it's literally easier to do and takes less time than wiring stuff up on protoboard, and actually designing the boards is pretty fun.
Also, is it me or is Eagle's interface fucking dogshit? Kicad is so much simpler and intuitive to me, although this is coming from someone who really likes blender's interface. Is there anything really useful I'm missing out on by not using Eagle?
>>
>>1208733
it's you. i happen to think it's the other way around.
>>
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My uncle kindly gave me a bunch of electronics parts from his garage. Now i'm trying to identify a dc motor which has no markings except for a pretty much illegible part code and brand logo. Printed silver on metallic grey and smudged away after years (decades?).

Question is: How can I get some data out of this motor to use it in a project? As in, nominal voltage rating, power in/out, stall torque, no load velocity? All I have to go on is "product of vietnam", and its dimensions (27mm diameter, 37 mm length)
>>
>>1208723
Say you apply a unit impulse to a filter. Simply, at zeros you have no output from the filter and at poles you'd have infinite (or upper limit irl) output.
>>
>>1208775
You probably can't, other than comparing it to other known motors of similar size and build.
All you can do is put some voltage on it and play around with it.
>>
>>1208775
>electronics.stackexchange.com/questions/132720/how-do-i-find-the-voltage-range-for-an-unknown-dc-motor
>>
>>1208787
>>1208788
ah yes the good old "google it". Somehow it didn't even cross my mind and the funny thing is if someone else had made my post I would have maybe been rude about it.
Double whammy because the solutions suggested in that thread I studied that shit in school.

tl;dr: i'm a fucking retard and thanks for the link.
>>
>>1208775
>no load velocity
attach very thin (light) piece of hard plastic to it, measure rotational speed with photosensor or fast enough camera.

>stall torque
get rubber band, measure elastic constant measuring elongation supporting a known weight. Tie rubber band to motor and see how much it stretch it, then calculate force from hook's law.

wonder how well it would work.
>>
>>1208733
KiCad makes a bit more sense to me as I've gotten used to it. There are a few nicer touches in Eagle 5.x such as a wider variety of track postures that seem to do the right thing more often, but that's really just icing on a urinal cake. The keyboard control of KiCad is bretty gud, and I hope they don't ruin that for a tool-based approach with the new canvas.
>>
>>1208723
> What the fuck are poles and zeros?
Given a rational function (one polynomial divided by another), zeros are the roots of the numerator (the points where the function is zero), poles are the roots of the denominator (where the function is infinite).

An R-C or R-L filter rolls off at -3dB/octave and has one pole. An L-C filter rolls off at -6dB/octave and has two poles. More stages means more poles and a faster roll-off.
>>
Since the pc power supply 12v sources are so popular. Are there any risks involved drawing 1.6A continously from the power supply since it provides 18 amps? The guides all have the load bearing resistor but I dont have any. What will happen?
>>
>>1208929
>What will happen?

nothing will happen. the requirement for having a minimum load on these power supplies stopped being true about 10 years ago.
>>
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>>1208723
If you look at a plot of the transfer function, poles bend the line down 3dB/dec, zeros bend the line up 3dB/dec. A single pole low pass has a single bend down, starts flat then drops 3dB/dec past the cutoff, if you add a zero to that the entire graph's bent up 3dB/dec, so rises at the start, then goes flat.
>>
I'm looking at this guy's schematic, and he's using shit I've never heard of:
>bat42
>TLV3501
>AP2530GY
Is there some database online I can use to find replacements/equivalents?
>>
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Are there like, grades of wire sheathing? I'm trying to buy bulk cable, and i want it to be as flexible as possible. If you've handled a rubberized guitar cable, or one of those headphone cables with the cotton braid inside the conductor that hang completely limp, you'll know the stuff I'm talking about, but i cant seem to find the right keywords to google it. I would just get mogami, but i'm looking specifically for thin (~3mm?) cable. I want specifically single conductor shielded cables (again, like for guitar cables), though i could settle for stereo if someone is supplying replacement headphone cable by the tens of meters. And even if I could find it, I'm not sure how to compare flexibility between manufacturers without handling the product. Minimum bend radius?
>>
>>1209016

There's not really any specific term for it.

Try searching for "silicone wire" or similar. You should turn up a lot of high strand-count, silicone-insulated wire, which is made specifically to be extremely flexible.

You might have trouble finding anything that thin, though...
>>
>>1209022

probably should've posted this this in here instead making a new thread but does anyone have an answer for me?
>>
>>1209032

It's fine. Technically, the heavier wire will actually be better than the 30AWG, but you aren't going to see any difference here.
>>
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>>1209016

one term i've heard is Litz wire (en.wikipedia.org/wiki/Litz_wire). each wire is made of very thin isolated strands which makes it extremely flexible and extremely strong. you could find it in old-school black rotary phone handsets, coz they were expected to last 30 years. however, they were always crimped coz soldering these was doable but very frustrating.
>>
>>1208547
Wow thanks, never guessed stray inductance would be fucking me up. I'm typically getting 0-1 clocks on the rising edge and ~8 (or some even multiple of) clocks on the falling edge of my momentary pushbutton. It has a strange detent, like the contact beneath is also spring-loaded. If only it wasn't a SPST or I could just put a SR latch and be done with it. Is it viable to add a big-ass inductor to the circuit to change it's resonant frequency into something low enough such that it doesn't matter? I have a couple of 1mH axial chokes lying about.

So when it comes to Schmitt triggers, I'll probably get a 74HC14, unless there's some reason I should pay 10c more for a 74LS14. To feed into the trigger, is pic related reasonable? Having a capacitor's exponential curves on both the rising and falling edges is probably the most sure-fire way to not send any bounce to the inverter, but if there are better methods (besides inverting the two parts of the circuit) I'm all ears.

>>1208807
Using elastic to measure force? That's genius, provided you stay away from inelastic deformation.

>>1209044
> they were always crimped coz soldering these was doable but very frustrating
How would you do either without stripping the individual strands' insulation? I hope you can just dip the ends in some sort of solvent.
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>>1209062
You'd think someone would have made a browser extension or something that stops you from posting if you've written "pic related" without uploading an image.
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>>1209062
>unless there's some reason I should pay 10c more for a 74LS14

two completely diff worlds. the TTL part would use resistors in the 500-2K range, whereas with the CMOS part can go into the megs w/o any problem.
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>>1209075
So with the CMOS I have more freedom in setting my R*C? What sort of caps should I be using anyways?
>>
>>1209007
You pretty much re-engineer the circuit to deal with the components you can get, which may or may not be easy. You could start by looking up the datasheets for the original parts, and then find similar parts with equal or better specs on the parameters that matter in each case. You may need to adjust other components to compensate for better gain or other attributes of the substitute.

>>1209102
>more freedom in setting my R*C?
Right. Capacitor type isn't critical. Ceramics with a C0G dielectric should be sufficiently accurate and not drift significantly over temperature or voltage.
>>
>>1209107
>C0G dielectric
>not drift significantly
For this purpose I can't imagine there's a ceramic cap in the world with significant drift, I wouldn't mind it changing by a factor of 2 or more. But I've no clue about what dielectric I'll be buying, I'll probably pick the 9.45USD packet of 60 assorted ceramics (definitely a shit deal) since I've got none at the moment, and there's no datasheet on their site. I'll just hope for the best.
>>
>>1209018
>>1209044
thanks lads, I'll have a look and see if i can find shielded silicone wire. And yeah, i've actually worked with litz wire before; what i do is scrape the end with an x-acto until you can see fresh bright metal on all the strands and then they can be twisted back together and soldered
>>
>>1209016
Also: sometimes sold as "test equipment" or "test lead" cable.
>>
I'm using an FTDI 232H usb to UART adapter to communicate with my fpga. The chip feature a max speed of 12Mbauds, but I noticed that while receiving data the flow control get triggered very often already at 6 Mbauds. Am I doing something wrong (for example, should I run the driver on the pc side on real time?) or the featured max speed just mean that it is able to peak at that speed, but not maintain it?
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>>1209267
Never underestimate the effect of marketing.
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>>1209307
well it's UART after all, and I forgot to say I'm also using the ftdi_sio driver shipped in the linux kernel.

The same chip has a "FIFO" interface with should get near the "high-speed usb2" rate. But I have to figure out why I can't enable that mode with the libftdi library.
>>
>>1206421
Circuit wizard, roast me.
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>>1209160
Some capacitors designed for supply decoupling can vary -20+80% over temperature. As long as there's "enough" capacitance, you'll be fine.

>>1209267
shiggy diggy doo, lern2usb if you care about speed
http://opencores.org/project,usb1_funct
http://opencores.org/project,usb
>>
>>1205055
Do you need a hug?
>>
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Sup, I have these two displays I took from printers, how could I drive them? Could I use them with an arduino?
They seem to be standalone, no circuitry on them.

I can solder SMD stuff, I have the ribbon connectors and pcb making skills.
>>
>>1209406
You need to develop reverse engineering and looking stuff up skills. Find a part number and go from there. A logic analyzer may also help.
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bump limit reached

new thread >>1209426
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>>1209407
How does one reverse engineer shit? I have some binary blobs that I need to disassemble, study and reimplement
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>>1209446
Next thread, m80.
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>>1209456
It literally takes a week for a thread to fall off /diy/ tho
>>
>>1209492
But it doesn't get dumped, and half of us probably close the last thread once the new one appears.
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>>1209519
*bumped
>>
I want to get into mirco controller and embed programming. I already know C and some ASM from finishing school, but doing system admin shit I don't get to really use any of that. I'd rather work closer to the metal. What's some good projects to get me going?I was thinking of making a small midi keyboard.
>>
P channel MOSFET suggestions?

Need TO220 3 lead package, positive line switching regular car brake light bulb filament - 3 amps or so but with large cold filament current spike. Gate drive is the same 12-14 volts DC. Such a large selection I can't make a decision.
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>>1209456
Wait, what? Why?
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>>1210092
New business is next quarter.
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>>1210027
if you can heatsink the fet on the chassis (or any heatsink) then absolutely any <250mohm 100V fet in a to220 package will do. 100v is necessary and even underspecced for load dumps. the irf9540s and 520s on ebay will work.

if you don't want to heatsink it then you'll want a fet reasonably below 100mohms. 60 would be comfortable. between 100 and 60 is maybe risking thermal runaway depending on the enclosure.
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>>1209446
That's exactly how you do it. Practice, practice, and more practice.
I recommend finding a journal called PoC||GTFO and reading from issue 0 all the way forward. By then you should somewhat understand the process and maybe know a few of the tools.




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