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bump limit reached on old thread >>1204692

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
>>
>>1209446
>How does one reverse engineer shit? I have some binary blobs that I need to disassemble, study and reimplement

You need a working knowledge of what the blob interacts with. After that, a disassembler and if possible, an emulator.

A legal note, if you're doing this for Real Work, you're not supposed to figure out the shit and reimplement it yourself. Best practice is to "cleanroom" reverse engineer, with one team doing the reversing, writing a spec, and another team doing the implementation from the spec. Copyrights or something.

If you're just doing it for the lulz though, yeah, have fun.
>>
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>>1209426
is this 1900?
>>
If theres any sparkies in this thread can you reccomend a good beater meter to keep in my truck toolbox, doesnt need to be fancy I only check shit on my car from time to time.
>>
>>1209663
Any cheapy from the local hardware store.
I prefer an analog meter for automotive because readings can be erratic with a digital.
>>
>>1209670
Anything to avoid? Not too worried about cost. Although I imagine most sub $50 ones probably come from the same factory.
>>
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>>1209662
>not liking incandescent and neon lighting

Get out.
>>
>>1209662
>File: bulb.jpg

I considered using that when making the thread, but resisted.
>>
I'm planning to do a yogurt heater thing. I need to keep the milk solution at a determined temperature for hours. How would I go on making a analog on off control? I don't want to use microcontrollers because I don't have money to buy those kits you use to code them. I thinking of using a butload of ampops with inputs from a termomether, is there a better way?
>inb4
>ampops
>analog
>>
>>1209707
Thermosistor, potentiometer and comparator

> I don't want to use microcontrollers because I don't have money to buy those kits you use to code them
A development board (arduino or msp430) can be found for about $10
>>
>>1209716
I'm not american. People here sell those things for 50 dolarinos. Which is more expensive than the thing I'm trying to make. I could buy one from ebay or aliexpress as it would not be taxed into oblivion (under 50$) but it'd take forever
>>
>>1209722
>>1209716
Also would this be a good one? http://www.ebay.com/itm/TI-MSP430-LaunchPad-Value-Line-Development-Board-Texas-Instruments-MSP-EXP430G2T-/111939937049?epid=1731827353&hash=item1a1023e319:g:kMQAAOSwAuNW66Ok
>>
>>1209723
Yes. It's the one I use.
Arduino might be a better choice for a beginner though

Adruino:
-5V that most modules use.
-simpler to code
-bigger community

MSP430:
-low power
-free code composer studio based on eclipse
>>
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>>1209707
>butload of ampops
You need only one, particularly if you're fine with on-off control. That is, if slight temperature oscillation isn't a huge problem.
>>
>>1209727
I'm studying EE in college, the thing is my Microcontroler teacher is a shithead that is using a 40 y.o 8051 so I skipped all his classes. In my university we get in touch with circuits and EE stuff in the 2nd or 3rd year (I'm getting there now) before that is all calculus and pain. I'm asking here just to be safe because I remember making a line follower detection thing for a robot with 3 ampops last semester but I don't remember a lot about it (Just that it was easy). Arduinos are a package right? A big bulky board with stuff and a MC lost in there somewhere right? I think I'll buy a launhcpad from ebay that way I can do embedded systems instead of arduinos strapped to stuff.
>>1209729
Thanks anon, I was thinking of two because of hysteresis? But I think yours has it. I'm getting into circuits and electronics this semester so optmization is still a problem for me.
>>
>>1209731
Why he does that? Because he is a civil servant and needs to kill the president to be fired. And he wrote a "book" on the old 8051 and is too lazy to change a bit.
>>
>>1209732
8051 is still used quite a lot and unless the course paid undue attention to oddities of 8051 like different memory areas, it is quite representative of the 8b controllers in general. Thus, it is a decent choice for a general introductory microcontroller course.
For reference, the original PIC is older and even AVR is two decades old.
>>
>>1209738
Yeah, I know that but he only delved into the odddities of the 8051, it's overlapping memory adresses, weird shit like moving to and from external memory and some other bullshit. Practical aplications for him range from writing MicroController in some internal memory adress to writing Microcontroller in the serial port. People just lost interest. Thankfully I know how nice MCs can be and have not faltered
>>
>>1209747
>>1209738
Ah sorry anon, I forgot to say. It's THE 8051 not it's derivatives :^)
>>
>>1209731

an 8051 is simple enough that a student can grok the entirety of the CPU in one semester: registers, flags, instruction set, I/O, memory map, stack. that knowledge is universal.

give students a modern CPU and they will overdose on details, and thus learn nothing except giving up.
>>
>>1209707
>temperature control
How much are we talking? Literally you could use a waterbed heater. If you didn't want to use the heating pad that comes with it, find out the voltages it lets get to the heating pad and wire that in yourself.

There's also aquarium heaters, which are already encased in glass and have a gripper so you can attach it to the side of a tank, if you had something stirring the yogurt. If it had to sit still, buy a bunch of aquarium heaters and attach them to an arm that sits above your reservoir. Won't be the most accurate, but very simple.

The waterbed heaters usually have numbers on their thermostat, I don't think aquarium ones do because of the variation in tank sizes (and the thermometer is usually in the same housing as the heating element)
>>
>>1209812
Only extremely old aquarium heaters are of the kind that apply constant heat. Modern ones do have an internal thermostat, and their temperature settings generally range from 22 to 30 degrees celsius, with 25 usually marked out in particular with a green stripe or something like that, since that's the temperature tropical fish prefer.
>>
>>1209747
Stuff like that is still useful knowledge to have since it maps to more complicated modern platforms. But it's true that students are not going to be motivated to learn on old platforms.
>>
I have recently gotten my hands on what appears to be the control board of an old printer, including two of its stepper motors. It has a usb type A port.

Could this board be embedded into future projects of my own, i.e. reprogrammed to do my bidding, and leave its printing days in the past? If so, how?
>>
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>>1209812
Keep it arround 80 Celsius for 20 minutes then 35 C for hours. I'm planning to use a pic related to heat it up (it can boil water).
>>
>>1209810
Yeah I know. But he also has the problem of being a bad teacher. If you do not read his book about quirks and irks of the glorious 1980 version chip you won't pass and he is kinda of an ass too. There are lots of simple chips out there, or simply a modern derivative of the 8051. ffs Msp430 has what? 30 instructions? A pic is much easier. But the problem itself was the teaching and focus not so much the chip.
>>1209833
yep :(. He focused on old architecture instead of the potential use in ebbeded systems
>>
>>1209707
>>
>>1209932
that's not /diy/ :(
>>
>>1209940
>that's not /diy/ :(
>he's buying a heating element
>he's buying controller boards
>he's buying a programmer for boards
He's already a buyfag.
>>
>>1209810
>overdose on details
>8-bit address space
hmmmmmmm

>>1209731
>optimization is still a problem
Those come with experience. I would encourage you to read some of the old National Semiconductor linear databooks, especially the Typical Applications sections of each datasheet. They are a gold mine of tricks guaranteed to activate your almonds..
Now, if you did want a circuit for an application where temperature oscillation was a big deal, you might set up a sawtooth oscillator at ~1Hz and connect R2 in >>1209729 to the sawtooth instead of +V.
>>
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mfw debunked
>>
Just getting started here. Should I get a 100 pin breadboard or a 200 pin breadboard?
>>
>>1210065
100 pins? That sounds small. Post pic
>>
>>1210072
I misremembered, I meant to ask 400 vs 800 pins.
And what are these? https://m.aliexpress.com/s/item/32454217006.html?spm=a2g0n.search-cache.0.0.70bc08b99Lj6c4
>>
>>1210075
Get two 400s if you can. That way you can work on a thing and set it aside to work on another thing without dismantling the old one. If you need to work on a bigger thing, you can snap them together temporarily.
>And what are these
Those are what you would need if you plan on interfacing your breadboards to some development board or Arduino. Otherwise just get https://www.aliexpress.com/item/Free-shipping-130Pcs-24AWG-Breadboard-Jumper-Cable-Wires-Kit-Tinning-Double-Tinned-Component-Pack-Colorful-13/32808331249.html
or, if you're not OCD and already have or can get a wire stripper, get a roll of 24awg solid wire and cut and strip a new piece whenever you need a new connection.
>>
>>1210078
Thank you!
>>
>>1210082
Personally I prefer the 24 AWG method, because you can cut the wires so they're flat against the breadboard, and apparently you can even salvage them from old network cables. They can usually be stripped with a single pull from my side-cutters, but my wires do have pretty shitty insulation.
>>
>>1209971
I'm not buying a controller board you retard. I'm buying a launchpad to program msps. Unless you have a magical way to program them manually shut the fuck up
>>1209977
>>overdose on details
>if you want to store something on external memory and the adress is longer than 8 bits you have to send one half to the port 2 registers and the rest to the adressable register you are using
>the 8051 then will concatenate that shit and it just werks
>it was a test questions worth 60% of the whole test :^))))))
>this thing is barely mentioned in the manual


>>1209977
> National Semiconductor linear databooks, especially the Typical Applications sections of each datasheet
I'll look into them anon, thanks!
>>
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>>1209370
>shiggy diggy doo, lern2usb if you care about speed
>http://opencores.org/project,usb1_funct
>http://opencores.org/project,usb

Doesn't really want to get too much into that mess, I'll probably go with the "easy" solution and get a USB-FIFO bridge. The cypress FX3 sound very interesting, enough to justify the ~50 dollars for a devel board.
>>
I ordered a handful of these micro usb heads to fix some ruined phone charging cables.

Do I need to wire anything but the +5 and GND pins? I see some people tying the data pins together. Does that change the charging speed or anything? There's also some ID pin floating in there
>>
>>1210170
>Does that change the charging speed or anything?
Yes. The device to be charged detects (is supposed to detect) the maximum available charging current by checking the data pins. Shorted = more current.
>>
>>1210170
do a google search for charging circuit for 'your phone'
some use shorted pins but other require specific resistors between each data pin and the power pins
>>
>PIC Controller
>>
Noob question. I'm troubleshooting a dead laptop charger that has an SL431 voltage reference.

Can anybody explain how this thing is used? It's said to be programmable from 2.5 to 36 volts but I don't understand how that is done.

datasheet: https://www.digchip.com/datasheets/parts/datasheet/058/SL431A-pdf.php

Thanks for any pointers.
>>
>>1210309
data sheet explains
>>
>>1210309
Figures 1 and 2 on page 3 don't answer your questions?
Or are you unfamiliar with zener diodes / shunt regulators in general?
>>
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>>1210313
equation
>>
>>1210313
>>1210314

Sorry. Maybe I'm beyond noob status, over in retard land.

>>1210315

Thanks.
>>
>>1210315
not him but i don't understand what's the point of having the equation for Vz in terms of Vref and Iref. I mean you only have R1 and R2 to mess with, right?
>>
>>1210391
It's a test circuit with a general equation for shunt regulators. Vref and Iref may change with temperature, aging, process, revision, or part number.
>>
help me out /ohm/. i (think) i have a fairly simple project.

i don't want a stereo in my shitbox car. i'm going to 3D print some black plastic center console panels to replace these fucked up ones the previous owner did. i want a single aux cord that goes to speakers powered by the cars electrical system. i found the fuse thats dedicated to the radio, what now?
>>
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>>1210488
pic related
>>
>>1210488
Not as simple as you think. There's a lot that goes into a car audio receiver. You probably would still want a volume control if you want to be able to unplug and replug the sound generating device without loud pops and hums, or even to adjust the volume while driving. You'll probably still want to be able to EQ for the car rather than swap EQ profiles on your mobile devices all the time. Good-sounding, reasonably powerful mobile audio isn't easy, especially with low electronics skill.
Maybe you want to replace that radio with a "digital media receiver" like this one, just for its amplifier and interface functions. http://www.pioneerelectronics.ca/POCEN/Car/CD-Receivers/DEH-X1810UB
>>
>>1210503
nah man. I'll just control it from my phone. I don't want a stereo deck. No knobs. No switches. Just the aux plug and car powered speakers. That's it
>>
>>1210522
Alright, then. I believe you're looking for something like this: https://shop.advanceautoparts.com/p/pyle-2-channel-300-watt-mini-amplifier-with-ipod-mp3-player-input-plmpa35/10240271-p
You need only mount it and wire it.
>>
>>1210534

interesting specs on that ''300W'' amp: 2 x 15 Watts RMS @ 4 Ohms/ 2 x 150 Watts Peak

anyone know why the FTC lets manufacturers get away with such blatant lying (calling a 15W amp a 300W amp) when they have the authority to stop these lying cock-suckers? i've been seeing this BS all over for like 10-15 years.
>>
>>1210569
Virtually all cheap amps rate at the peak output they reached before catching fire in testing. If you're not automatically disregarding the tagline and looking for RMS, you're shopping wrong.
>>
>>1210569
>i've been seeing this BS all over for like 10-15 years
It's a much, much older phenomenon. I doubt it's going anywhere at this point.
There's also a tiny sliver of truth behind the numbers, so if shit goes to court, they might be able to claim that the given numbers are justified.

Either way, at least they indicate the RMS power.
>>
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>>1210391
>you only have R1 and R2 to mess with
Right, but 'to mess with' includes the order of magnitude. Imagine you want Vz to be close to 5V and you happen to have two resistors of 1MΩ each, one for R1 and the other for R2. What will Vz turn out to be (given Vref=2.5V and Iref=2µA)? According to the equation you should expect 2*Vref + 2µA*1MΩ = 7V, not close to 5V. If you use R1=R2=10kΩ you would get 5V+20mV, which is close to 5V. Pic shows a similar detail, the minimum value of Iz.
>>
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I cannot identify the IC that the red arrow points to.

It's hard to see, but it has six pins. If you start counting the lower left pin as number 1, pin 1 is connected to the emitter of an opto isolator and pin 2 is connected to the collector of that isolator.

Pin 3 is connected to pin 1 by 100k resistor. If you continue counting with pin 4 opposite 3, pin 4 is connected to the source of a power mosfet which is also connected to ground by a 0.6 ohm resistor. Pin 5 goes to +Vdc through two 750k resistors in series. Pin 6 goes to a 47 ohm resistor connected to the gate of the power mosfet.

Unfortunately the face of the chip does not have much information and nothing shows in the photo. It looks like a large graphic G, then a space, a small r, then a p, then either 358 or 35B. I found a neat site full of IC vendor logos but nothing looked like the G.

More extraneous info: the opto isolator is a Cosmo 1010 and the power mosfet is ST P4NK60ZFP.

Thanks for any information or suggestions.
>>
>>1210676
Wait, are you sure the same IC is connected to both sides of an isolator?
>>
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I'm feeling rather stupid. I'm trying to get a 3.3v logic controller (f.e. an esp8266 or another arduino-like) to output between 6-12 volts (to power some leds/small pumps etc) but can't seem to figure out how to do this. I've ordered some mosfets but I'm afraid I made a mispurchase as those seem to only trigger from 10v.

How could I get the 3.3v of an esp8266 (or the 5v of an raspberry/etc) up to 6 or 12 volts while allowing some (at least an Amp, preferably a lot more) current through?
>>
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>>1210681

Looking at the traces and probing for continuity seems to say yes. I suppose this implies that the unknown IC has an internal pullup on the collector of the isolator?

It also appears that the isolator emitter is grounded, as the blue line is a ground trace.
>>
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>>1210684

Here's the other side. You can see the dot for pin 1.
>>
>>1210682
>current
because you said current i'll try and help you out.
fet is just a voltage controlled current gate, like bjt is current controlled current gate. so you could use either of those. for bjt you would need a huge gain (hfe on datasheet) or you can chain them, look up darlington pairs. set the base current with a resistor based on chip voltage - transistor turn on voltages.
ok so then you can use a mosfet but yes you need to turn them on with voltage. you want to choose npn vs pnp based on the logic level you want around a low side switch otherwise of you go high side your pretty much fucked with voltage levels.
just search for logic level mosfet, they do exist companies make them specifically.

of course the other way is some kind of relay, solid state relays are becoming much more common now so you can maybe find some of them but then you might need a transistor to drive that too!
>>
>>1210569
Sometimes they call it PMPO, peak something. No tweaker is going to be satisfied with something that says 10W, even if that much is deafening.

Anyway, looks like a T-Amp.
>>
>>1210676
No clue what the actual type is, but there are several similar ICs with (apparently) compatible pinout. This compatibility goes beyond pinout, too.

www.first-semi.com/firstsemi/DownFiles/20111120185551748.PDF
file.yizimg.com/332467/2010080308450435.pdf
www.micro-bridge.com/data/CRpowtech/PT4201E.pdf

The last two have kinda G-like logos, if you use some imagination.
>>
>>1210688
Thank you for your reply/explanation I had not thought of chaining two of them. Maybe it will even work with the ones I have. Going to try this.

P.s.(What's up with me saying current?)
>>
>>1210695

Excellent work. Looks like a perfect match.

Thank you sir.
>>
>>1210702
if you had said amperage i wouldn't have bothered
>>
>>1210718
Ah, well thanks for bothering :)
>>
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Anyone using See Electrical V8? Is it worth it?
>>
>>1210760
Had to use V7 for uni. Fucking hated it.
>>
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>>1210702
>chaining
What MOSFET exactly? If you were lucky, you will have ordered N-channel enhancement-mode, in which case you could try using a BJT to get the voltage needed like Pic related. The circuit should work as drawn for any logic level down to 1.8V. Note the active-low input and beware that weak pull-ups on the controller might be too weak to turn Q2 on. In that case reduce R3.
>>
>>1210689
>satisfied with something that says 10W
When I was young, I remember reading that Paul Klipsch had taken one of his speakers and a five watt amplifier to Carnegie Hall and filled the auditorium with music.

A lot of factors involved I don't recall. Was the auditorium full or empty? Which speaker did he use? (probably a Klipschorn) Who decided the music "filled the hall"? Still, I was impressed enough to not forget the main claim.
>>
>>1210682
>I've ordered some mosfets
Which type?
>>
>>1210685

the big cap in your picture definitively looks bulgy. take a look at it in profile to verify. bulgy caps are one of the main problems in switching power supplies.
>>
>>1210888
>probably a Klipschorn
Sensitivity 105-110dB... Yeah, at that sensitivity a 5W amp is equivalent to a normal speaker + ~500W amp. The criteria for "hall filling" was most likely more reasonable than today, too.
>>
>>1210888
>Klipschorn
*Klipsch-Horn
>>
>tfw the more you read up on electronics and programming the more your realize just how much there is to know
Should've just picked EE. Stupid mechanical engineering...
>>
>>1211216
M8, the more you study EE the more you see everything is an EE problem.
Here in my place all mech eng students are faggots with superiority complex
>>
>>1211224
Here in my physics department everyone has an inferiority complex because they weren't good enough to get into engineering.
>>
>>1211229
In my uni generally young (as in student) physicists are quite full of themselves.
>yeah, engineers? those guys that design stuff but don't actually understand physics?
>biologist? pff, soft science.
sometimes I even hear theoretical physics student making fun of applied/experimental physics for being "simpler" or involving less math.

But luckily, I don't really meet those kind of people anymore since I started my master, I guess that kind of ignorance gets mostly skimmed out during bachelor's.
>>
what site has the best prices for arduino bulk?

adafruit's mark up is insane
>>
>>1211216
>>1211224
its honestly just the world we live in nowadays.

any discipline of engineer should be learning a programming language or two and have a good working knowledge of control systems. digital age and whatnot.
>>
>>1210952
>the big cap in your picture definitively looks bulgy.

Yes it is. Excellent observation from that blurry photo.
>>
How hard would it be to retrofit something like this with thermoelectric cooling? I need it to be silent
>>
>>1211298
>How hard
Vague question, depends on knowledge and skills. Peltier cooling needs 4 times the energy of a compressor cooler. Large heat sink plus fan(s) required. Not silent and heats up the room making it even less efficient. Get a used Peltier beverage cooler and see if it's what you want. www.google.com/search?q=peltier+refrigerator
>>
>>1211338
>Not silent and heats up the room making it even less efficient.
What if I only open it once or twice per day, don't need it to cool shit very quickly, and put the temp at 8°C in an ambient temp of 23? Will it still need noisy fans?

I have basic electronics tools and knowledge.
>>
>>1211354
15C temp difference and a heat sink with fins the size of the object may work without a fan. The crucial point is the heat transfer with a low thermal resistance between the Peltier module(s) and the interior. The heat exchanger on the back may have a flat enough area for that. I think there are kits with instructions about how to do it. They usually have a fan or two but this is to make them work with rather small heat sinks. I had one of these cheap 12V bucket-type camping coolers but it was too inefficient compared to the old-style totally silent absorption coolers.
>>
>>1211250
clones okay? Aliexpress.
>>
>>1211549
Are ICs and boards from aliexpress always sound? What is the chance of getting defects?
>>
>>1211570
>What is the chance of getting defects?
SMDs seem to be soldered ok

headers and sockets may be cockeyed
>>
>>1211549
I bought one yesterday
>>
>>1211570
i've ordered 5 of the ch340 knockoffs. they work fine with the correct driver.
>>
>>1211570
Usually. I've only gotten one duff assembly so far, but it was a power adapter with a solder blob rattling around inside ffs. The only other minor error was a mislabeling between common-cathode and common-anode RGB LEDs. Two years and several hundreds of dollars in stuff later, everything else I've gotten from Aliexpress seems to have been assembled correctly.
>>
>>1211216
As an EE, there is plenty of mechanical knowledge that I would love to have. Break the mold and don't ever stop learning.
>>
Can anybody give me a quick rundown on issues surrounding replacing a power source from AAA batteries to a LiPo cell?

Basically, I am messing around with toy quadcopters right now, and I have a spare 750mAh LiPo I want to swap into my eachine h8 mini controller in place of AAA batteries. The AAA's are wired in series, so I believe the voltage will not be an issue. Is it as simple as AAA nominal peak voltage: 3x1.5v = 4.5v vs LiPo 1c nominal peak voltage 3.7v? Is amperage going to be a factor here or am I retarded? What I want to do is wire the battery leads to a JST female connector, and then connect the liPo cell to the JST connector. I think what will happen, is the battery will be able to supply the required voltage for less time than the AAA's, which typically come in between 750mAh - 2000mAh each, but still be able to operate the remote for a few flying sessions.

Am I like, retarded? Anything else I need to consider here? I realize the LiPo cell I have is not going to last as long as 3 AAA batteries. But in the long run it won't cost me any money to replace. And it will be another fun practice project. Just want to avoid destroying the controller if I can. Thanks fags
>>
>>1211753
3.7V may not be enough to run the remote properly, try measuring voltage across the AAA batteries in circuit when it's just run out to see how low it can go. Depending on transmitter design you may get less range when running lower voltage.

If you do need a higher voltage using a small boost converter module can work, or go two lithiums + a linear regulator to step voltage down if you want lower noise at the cost of lower efficiency.

Overdischarging (and overcharging) LiPos is bad, you should use a protected battery that'll switch off automatically when it gets too low. Cellphone replacement batteries are a good source for those.
>>
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>>1211735
MIT's "How to Fabricate Almost Anything" should be mandatory high school graduation material imo.

>>1211753
Test by running the controller on 3 fully charged AAA NiMHs. If it runs well with those 3 * 1.2V = 3.6V, it should run well with LiPo, as far as voltage is concerned.
>I realize the LiPo cell I have is not going to last as long as 3 AAA batteries
Pic related... maybe? Here are discharge curves of who the hell knows what alkaline AAA and of who the hell knows slightly smaller LiPo, as if the first images I find on iamge search are somehow representative. They aren't exactly comparable, but they do illustrate that run time is very dependent on discharge rate, and suggest that a LiPo in good condition may be slightly superior in that respect to alkalines. To know for sure, you really do need to have a good idea of the current consumption of the controller when active. (C = the battery capacity/hour, in this case 750mA)
>Anything else I need to consider here?
The controller will probably take any voltage a LiPo will put out without damage. The LiPo, on the other hand, should not be run to a very low voltage for longevity. 3.2V is a reasonable, if slightly conservative guideline. If they go much below 3V, they may react poorly when next charged.
>>
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Make a faceplate out of PCB material, check.
To do: draw traces for 13 DIP ICs and etch them and solder them to 90 LEDs, 10 rotary switches, 10 binding posts, a bunch of switches, and a crystal.
>>
>shop for motors
>gcm
>oz-in
>Kg-cm
>mN
JUST FUCKING GIVE ME THE TORQUE IN Nm HOLY FUCK REEEEEEE
>>
>>1211930
>he doesn't speak american
>>
>>1212043
oz-in wins, no idea what that means
>>
>>1212046
You have: oz*in
You want: lb*ft
* 0.0052083333
/ 192
You have: oz*in
You want: g*cm
* 72.007789
/ 0.013887387
You have: oz*in
You want: N*m
conformability error
0.00072007789 kg m
1 kg m^2 / s^2
>units ftl
>>
>>1211764
>>1211777
Thanks anons.
>>
>>1212051
>conformability error
now you're kidding me
1 ozf = 0.278 N
1 in = 0.0254 m
1 oz-in = 7.06 mN·m
>>
>>1212043
>he uses units of mass for force
>>
>>1209707
You can get a PID temp controller fit under $20, get a hot plate, and thermocouple you have everything you need. I don't think you will find a better solution for less...also, what temp do you need to keep it? You might need a waste bath/double boiler setup to keep it from scalding.
>>
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/ohm/, I need help picking up a cheap beginner DMM. I watched Dave from EEVBlog review AN8008 yesterday and he said it was a good deal. He didn't like some milliamp ranges but he said it was good. It costs around $25.

The specs are here:

https://www.aliexpress.com/item/ANENG-AN8008-True-RMS-Digital-Multimeter-9999-counts-Square-Wave-Backlight-AC-DC-Voltage-Ammeter-Current/32810125781.html

The second chinkshit DMM I'm looking at is UT139C. Dave hasn't reviewed it but there are tons of other videos showing it's okay for electronics. It's like $7 more and it comes with a thermacouple.

https://www.aliexpress.com/item/UNI-T-UT139C-True-RMS-Digital-Multimeters-Electrical-Handheld-Tester-Multimetro-LCR-Meter-Ammeter-Multitester-With/1000001457574.html

Both of these are probably HUGE SAFETY HAZARDS and should not be used on mains but I don't care about the mains anyway (strictly bench top electronics).

So tell me guys, which of the two would you pick after looking at the specs? I'm an electronics newb and plan on using it for learning so I'd appreciate some advice. Thanks!
>>
>>1212250
I wouldn't worry too much about mains but that 600V rating, eh. I've never heard of Aneng but UNI-T is kinda sorta a real brand, they've been around for a while at least.
>>
>>1212250
>>1212355
If it's any consolation, I stick my $10 shitmeter in 240V sockets and I've never gotten a smidgen of a shock. But I only trust it that far because It's sold by a somewhat local brand with somewhat of a reputation to keep. If you're not doing mains voltage things then there's really nothing that can go wrong, especially at those prices.
>>
reminder that people who use imperial units are just as bad as people who say amperage.
>>
>>1212250
>Both of these are probably HUGE SAFETY HAZARDS and should not be used on mains


This is basically a bullshit /diy/ meme. If you don't know how to work around a few hundred volts then you will fuck up with any meter you own.

See that power cord over there? IT'S A HUGE SAFETY HAZARD if you don't understand electricity at least on a beginner level. Last week a girl was electrocuted in her bath tub by a smart phone - no wait if you read the whole article it had nothing at all to do with a smart phone or a smart phone charger but rather it was that fucking extension cord she was messing with while in the tub.

>>1212432
>I've never gotten a smidgen of a shock

And you never will. Cheap assed multimeters don't somehow mysteriously leak voltage all over the place. Cheap assed multimeters might be inaccurate and the switches might fail prematurely but containing a few hundred volts is not hard to do.
>>
>>1212432
To be fair, pretty much every Chink meter can measure mains voltage without killing you - most of the time. Depending on how often you use it and how careful you are, there's a good chance nothing bad happens to you, ever.
That said, there's a big difference between designs which "usually won't hurt you if you're careful" and designs which actually are safe and reliable. This is particularly obvious with current ranges, where a shitty meter can literally explode.

>sold by a somewhat local brand with somewhat of a reputation to keep.
If it's the meter in you pic, there's zero reason to assume it is any better than the other identical looking meters of different brands.
>>
>>1212441
>This is particularly obvious with current ranges, where a shitty meter can literally explode.

How exactly? The only problem I've ever had with current measurement is that the 1 amp fuse gets all pissy and blows when I put 5 amps through it.

Explain how you can explode a cheap meter but an expensive meter can handle that improper abuse. I suppose if you apply a 12 volt 800 cold cranking amps car battery to the 200 ohm resistance scale bad things might happen.

A 200 dollar tool will not protect a novice from making novice mistakes. Electricity is dangerous. Don't fool around with it until you learn the basics.
>>
>>1212441
>If it's the meter in you pic, there's zero reason to assume it is any better than the other identical looking meters of different brands.
But it must have legitimately passed certification, not the fake garbage from AliExpress. I wasn't comparing it to other models of the same design, but rather to things like the AN8008 which likely aren't being sold in stores outside of China, so there's no way of knowing whether it would pass. But it probably would unless there's one obscure fault.

More to the point, if I plug in a multimeter to the wall and burn my house down, if I bought it from my local store I can claim their liability, but if they learn that I bought something from AliExpress instead, I'll be coughing up the dollar bills. It's a shame my local stores only sell Mastech clones and UNI-Ts, but at least we have a few online Fluke distributors.
>>
>>1212443
>1 amp fuse gets all pissy and blows when I put 5 amps through it.
A wall socket or a distribution panel can provide quite a lot more than just 5 amps and the glass fuses you usually see in those shit meters have rather limited breaking capacity. When it is exceeded, they explode. Optionally, the initial arc might not extinguish.
Better meters have (much) better fuses and in general they have proper protective circuits and clearances. In comparison, some $5 meter might not even bother with proper PCB clearances.
In >>1212432's case, the current range is immediately next to the AC volts range and the current range shares the same contacts as well. That's a rather accident-prone arrangement.

This isn't to say that nothing bad can happen with better meters, but at least the chances are much lower.

> I suppose if you apply a 12 volt 800 cold cranking amps car battery to the 200 ohm resistance scale bad things might happen
Your meter is pretty bad if you can kill it with something like that.

>A 200 dollar tool will not protect a novice from making novice mistakes.
No, but fewer novice mistakes present an immediate hazard and fewer mistakes kill the meter. Whether the latter is worth the price tag is another matter and the former can usually be prevented with a simple, easy to understand rule of "don't stick your Chink meter to the wall socket".

>Don't fool around with it until you learn the basics.
Accidents happen and things like occasional overvoltages in the mains are difficult to predict.
>>
>>1212454
>Better meters have (much) better fuses

You made a lot of good points, but this one seems a bit shaky. Could you elaborate? Also, this whole exploding fuse thing. Is that anecdotal or for real? Do they explode with enough destructive power to come through the meter casing?
>>
>>1212220
>he doesn't know that m=f/a
>>
>>1212461
>Also, this whole exploding fuse thing. Is that anecdotal or for real?
For anecdotal evidence, I've seen it happen twice.
For real evidence... The breaking capacity (interrupting rating) of fuses is more or less related to that. See for example http://www.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_fuseology_selection_guide.pdf.pdf.
For alternatives, Fluke's fuses are a well-known (annoying) example of fuses which have high breaking capacity.

What comes to exploding multimeters: professionals occasionally get hurt that way when they use their (expensive, well-designed) meters way beyond their ratings. These are usually reported to authorities. IIRC OSHA's listings have such cases.
For a video, see https://www.youtube.com/watch?v=i9jpwGTy66g
>>
>>1212230
80 C for 20 minutes and 35 C for 8 hours. I'm planning to use this.>>1209847
>>
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Behold my waifu
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>>1212495
lol
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>>1212437
So what's the ohmage on that resistor?
>>
>>1212670
ohmage is voltage over amperage or wattage over amperage squared or voltage squared over wattage
>>
>>1212670
What is the faradage required in an oscillator, given the ohmage and henryage of the other components?
>>
>>1212687
>henryage
doesn't that depends on the yardage of the coil?
>>
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>>1212687
Discrete design is fun.
>>
shouldn't something like
eq <= '1' when (A = B) else '0';
always result in a simple iterative comparator in vhdl?

With A,B bigger than 12 bits quartus goes out of memory after consuming ~7 GB of ram.
>>
>>1212788
Are both A and B std_logic_vector?
>>
>>1212476
The kilogram is a measurement of mass, and the newton is a measure of force. But the pound is ambiguous, because it is used for both. When dealing with imperial units you cannot simply use a dimensional analysis without taking this into account.

Also I don't suppose there's anything wrong with running the output of my crystal oscillator through a Schmitt trigger, is there?
>>
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>>1212432
thansk for the info. so all these ppl who claim this shit will kill you are full of shit?

even if the DMM gets blown up by the current, can it really kill you?!?!?

or will the probes melt in your hands and kill you or some shit like that?

how the fuck does a DMM kill you!??!
>>
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>>1212887
>running the output of my crystal oscillator through a Schmitt trigger
As long as you're not too fussy about the duty cycle, go ahead.

>>1212899
You mean by the voltage? Yes.
http://www.ecmweb.com/arc-flash/case-deadly-arc-flash
>>
>>1212911
>The store was located in a large mall facility with an electrical system that was 480V, 4-wire with 277V from each phase to ground.
for fuck's sake... I don't plan on putting chinkshit on a 3-phase circuit. I don't even have that shit in my house. I'm pretty sure it will be OK for 110V or (220V if I ever plug it into a stove or something but I would never do that anyway).

can it kill you if you put it across 110V mains??
>>
>>1212439
>Cheap assed multimeters don't somehow mysteriously leak voltage all over the place.
leave the probe in the current socket by accident then come back and tell us how great shitty meters are when you can't sit down to type because all the skin that used to be on your ass is now your new hand.
good meter doesn't just put up with it, they bleep at you if you have a potentially dangerous lead/measure combo.
>>
>>1212915
Oh, at 240V arc flash is scarcely a concern.

>>1212918
I argue that good meters don't have voltage measurements and currentage measurements on the same + jack.
>>
>>1212924
>Oh, at 240V arc flash is scarcely a concern.
Phew, OK!

BTW, if a professional electrician/HVAC installer uses cheap chinkshit to do work, they deserve what's coming to them. It's pure Darwin.
>>
I need to make a machine that weighs things. I need to go to max of 10kgs (and i need it to at least separate 1 individual gram from the others) in one section and up to 600kg in the other.

Will the ADS1231 coupled with some loading cells be what i'm looking for?
http://www.ti.com/product/ADS1231

Can /diy/ recommend me some loading cells, or another AdC if it's necesary? I need to minimize costs as much as possible, but i can't go lower than 5grams each measure

How do i know what accuracy can i get reading the datasheets?
>>
>>1212943
With "lower" I mean worse resolution
>>
Is this an electrician/lineman type thread too, or just for hobbies?
>>
>>1212999
imo have something to do with L, R, and/or C, and you're in.
>>
>>1213005
I'm not a lineman yet, about to start line school, so I offer very little knowledge. I was just curious as to where others like me would be lurking.
>>
>>1212788
Is that inside a clocked process?

>>1212943
I don't have experience with load cells but from what my friend told me about his DDR pads, I doubt that you'll get 1g resolution or accuracy on a load of 10kg.
>>
>>1212885
Both natural range 0 to 2**15

>>1213017
>Is that inside a clocked process?
No, but A is a signal calculated inside a clocked process and B is a constant.
>>
>>1213017
>DDR pads
Dude.

1g resolution is trivial to achieve. 1g noise (around 2µV) isn't a big deal either. 1g accuracy can require decent amount of work and money, if you're actually serious. Either way, much better than 1g out of 10kg is possible with load cells.
>>
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I hope this is a proper post to post in, rather than make a new thread.

I have a subwoofer, a decade or so old. It got repaired a year ago and now it broke down on me again.

Only thing that I find out of place are these capacitors that seems to have shit themselves.
Googled, leaking capacitors seems to be a thing?
I'm not very experienced about this particular thing.

It won't even turn on, seems weird that these two capacitors(on the settings board) would stop it from doing that, no?

Anyway.
If these are the faulty bits, would I be able to get a hold of a new pair and resolder?
>>
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quick question.
I have got a transformer that has one input (230VAC) and outputs 2x 18VAC.
I want to have 1x 36 VAC as an output.
Can I just connect the two outputs in series?
>>
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>>1213163
Some info on the caps themselves.

I've managed to find a whole bunch of them on conrad.se.
But there's so many and I don't know what more to look after other than to match the numbers.
>>
>>1213163
>>1213169

Yes that's pretty common and may be the problem.
And yes, you can replace them with any other cap with same specifications, you need caps rated for 25V and 1000 microfarad capacitance.
>>
>>1213172
Awesome, thanks!

I just realized that all these images of the capacitors I'm looking at have different specs on them.
>>
>>1213167
yes
>>
>>1213178
thx
>>
>>1213107
>1g resolution is trivial to achieve. 1g noise (around 2µV) isn't a big deal either. 1g accuracy can require decent amount of work and money, if you're actually serious. Either way, much better than 1g out of 10kg is possible with load cells.

That's amazing to hear! Is there any book or page or, well, any reference you could guide me to?
You make it sound like the accuracy is something that goes beyond the models I pick. Are you implying that i can "Squeeze" a better resolution out of a poor buying decission? or you mean that I can easily get a worse resolution than expected if I screw up the design?
>>
>>1213107
>>1213208

The ADS I mentioned offers 35nV(rms). That sounds extremely good. Can i expect good things from it and go straight into looking for the loading cells or should i keep looking?
>>
>>1213179
There are two ways to connect the windings in series. One yields the sum, the other the difference.
>>
>>1213103
>>1212788
Apparently the problem is not the comparator but a 15 bits counter (A). Still don't understand why it would take more than 8 GB of ram to synthesize that, the code is basically:

if X then
A <= A + 1;
end if;
if Y then
A <= A - 1;
end if;

Inside a clocked process, I use it to keep track on the number of "words" recorded into a memory and X and Y are "mem read" and "mem write" signals.
>>
>>1213264
oh god I am retarded, I typed the wrong constant in a vector definition in another file that was defining a ridiculously long std_logic_vector.
>>
>>1213163
>seems weird that these two capacitors(on the settings board) would stop it from doing that, no?
Without them, the settings board, which probably controls the rest of the system power, only gets power for 10ms at a time.
>>
>>1213208
I'm implying that load cells with much better specifications exist. Naturally lesser load cells produce better results too, if you treat them nicely (constant reasonable temperature, sufficient warm up time, loading comes from the correct direction, you don't keep them heavily loaded, etc.)
Of course you can fuck up and end up with a shitty design. This applies to the mechanical part, too.
The advertised noise of your converter is the RMS noise, meaning that you'll see 3-4 times bigger deviations from the average quite often. Due to the limited input voltage range, you might also end up with lower bridge excitation voltage, reducing the signal to noise ratio. Even then, 4 noiseless digits isn't difficult to achieve. You can filter the readings with software, too.
From the electronics point of view, 50/60Hz noise, cell phones and thermal voltages are your principal problems. The converter itself helps quite a lot with the first two problems. The latter... You can nearly eliminate it by feeding the bridge from an AC source or you can try to compensate it with balanced layout. Or, if the requirements aren't high, you can try to live with it. Gain error might also be present, so ratiometric measurement and self-calibration can be used. The converter itself supports the former, but apparently not latter.
The load cell itself has temperature coefficient too, affecting both offset and gain.

Generic info about load cells can be found from manufacturers' literature and books related to instrumentation and instrument transducers. ADC datasheets often have relevant application examples, too.
>>
i need an assortment of plugs and sockets and pins similar to pic related of different lengths and rows (mostly 2x1, 2x2, 2x3 and 2x4). they can be either blade or pin. cant seem to find an assortment kit, mostly just individual bits. where2buy?
>>
>>1213380
try aliexpress?
https://www.aliexpress.com/item/10sets-2-Pin-way-4-2mm-5556-5557-5558-5559-automotive-electronic-connectors-plug-Housing-Terminal/32710126364.html
>>
Hi /ohm/. I'm in the market for a good new multimeter. I'm looking for the Hakko FX888 of meters, so to speak. What do you anons like?
>>
>>1213380
or ebay if you don't want to buy from china
http://www.ebay.com/itm/78pcs-Molex-3-0mm-1x2-2x4-Connector-Shells-200pcs-M-F-Crimp-Pin-Kit-Case-/141717124999?hash=item20feffb787:g:SqoAAOSwHnFVorqQ
>>
>>1213391
>>1213410
o shit, guess im retarded. not sure how i couldnt find these. thanks anon
>>
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>>1213380
on an unrelated note, I only ever used molex connectors in computer PSUs, and I don't even want to imagine how much of a bitch the thing in pic could be.
>>
>>1213402
>>1212250
>>
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>>1213163

those capacitors are almost certainly fine. the goo is glue to keep the caps from becoming loose under vibration.
>>
>>1213439
correct, they just applied a bit too much of it
>>
>>1213434
Cheap beginner chinkshit is exactly what I want to avoid. I want something good. It's going to get used daily.
>>
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>>1213415
You wouldn't be dealing with so much of Pic related on Molex connectors, which btw are not AMP Mate-N-Lok connectors.
t.pedantic autist

>>1213447
>It's going to get used daily.
GO TO FLUKE
GO DIRECTLY TO FLUKE
DO NOT COLLECT $200
>>
>>1213452
>FLUKE
Any specific model you would recommend? I've heard the cheaper Flukes are chinkshit now too.
>>
>>1213493
Maybe compared to the better ones, but they're still probably a far shot better than whatever no-name chinkshit brand you care to buy.

Have a look at the EEVblog forum's spreadsheet:
http://www.eevblog.com/forum/testgear/multimeter-spreadsheet/
>>
>>1213163
>>1213439
>the spread is flat and clear corrosion of contacted pins

I wouldn't be so sure of that.
>>
Is there a standard way of allocating the frequency bands in an audio frequency analyzer? I want to have 12 bands across the audio range, and the center of each will be a fixed multiple from the previous. But I don't know about the width.

Anyone got any thoughts?
>>
Hi

Can you put a 20a GFI receptacle on a 15a circuit? What if its a smart GFI?

Ive heard that most 20a GFI's are actually 15a receptacles with a 20a pass through

Then other times, I have read that youll get an instant trip on the GFI if you put a 20a on a 15a circuit.

Any input?
>>
>>1213560
Using the traditional 20Hz-20kHz range, you'll have three decades of frequency, therefore four bands per decade. For example, you would have center frequencies of approximately 25Hz, 50Hz, 90Hz, 150Hz, 250Hz, 500Hz, 900Hz, 1500Hz, 2500Hz, 5000Hz, 9000Hz, 15000Hz.
Since you probably want roughly even frequency response, figure on placing each band's 6dB down points at least ±1/8 decade (-25%+33%) away from center, which translates to a Q of no more than about 1.72.
>>
>>1213560
Sounds similar to octaves, where an A at one octave is twice the frequency of an A of the previous.

Going from 20Hz to 20kHz there's a multiple of 1000, which rounded to 1024 gives you 10 divisions of 2. Going by octaves divided by C you get 9 fully audible octaves from 1-9 inclusive, and two partially audible octaves of 0 and 10. This gives you eleven bands, so just add another super bass (or super treble if you swing that way) and you're set.

And fyi, the A above middle C (C_4) is 440Hz, and notes within octaves are separated by a factor of 2^(1/12) or 2^(1/6), alternating like: "6,6,12,6,6,6,12,6,6,12,6,6,6,12" with the "12"s between E and F, and between B and C.
>>
I bought a bunch of LMV358 (fairchild) op amps because they are supposed to be rail to rail.
When I use a single 5V supply and I apply In+ = 5V, In- = 0V, the output is saturated around 4.9V.
But I want to use the op amps as buffers. When I short circuit In- with the output, and I apply In+ = 5V, I get an output voltage of around 4.1V.
Why is there a voltage drop? Am I missing something?
>>
>>1213649
"Rail to Rail" really means "closer than 2V to the rails", except for fairly modern devices. What does the datasheet say?
>>
>>1213653
>What does the datasheet say?
It says the typical output range is from 0.036 to 4.95, and this is what I measured without the feedback.
The problem is with the buffer configuration.
>>
>>1213657
Configuration sounds fine. What happens if you lower the input voltage to 4.1V?
>>
>>1213657
See where it says R_L = 2Kohm to 2.5V? I suspect that may have something to do with your issue.
>>
>>1213660
when the non-inverting input < 4.1V, the output = input.
it seems the op amp saturates at 4.1V when I use it as a buffer.

>>1213662
I saw that, but I tested it without RL and with RL = 3k7 Ohm, and the results were the same.
>>
>>1213675
Try in a non-inverting amplifier configuration and see if it rails at 4.1V.
>>
>>1213675
Hmm. Where did you buy them from?
>>
>>1213675
Why not just use it for an almost unity gain amplifier with a few MΩ as the resistor to ground? You might have to put a few ohms/kΩ as the feedback resistor.
>>
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>>1213676
With R1 = 2k2 and R2 = 3k7, I get 4.9V max output. If I remove R2 or if I short-circuit R1, it drops back to 4.1V.

>>1213678
local reseller. buying from the us or europe would be quite expensive.

>>1213681
The voltage drops when I try using R2 much greater than R1.
>>
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>>1213649
>rail to rail
>LM358
Who told you that? The only thing I see in the Fairchild data sheet regarding input range is "Input Common Mode Voltage Range Includes Ground". Rail-to-rail support varies based on input vs. output and which rail.
Since you do have -V rail capability, try dividing the input by 2 then multiplying it by 2 with the gain stage.
>>
>>1213685
You sure the input is at 5V? I'm thinking if it's 4.1 that would explain everything you've said.

I'm about to sleep but good luck.
>>
>>1213687
lmv358, not lm358.
it seems the circuit you posted worked. I got output = 4.9V with input = supply = 4.98V.
if input < 4.9V, output = input.
I may need low tolerance resistors if I use a high resolution ADC though.
I wonder why I can't just use the regular buffer circut.

>>1213695
yes. I only changed R1 and R2 on the breadboard.
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>>1213699
While it has a rail-to-rail output, it does NOT have rail-to-rail inputs. Maximum input voltage at 5V supply is 4V.
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>>1213733
that makes sense, but where do I find that kind of info in the datasheet?
>>
>>1213746

I'm not sure either. I don't understand pic related because the typical is greater than the max and less than the min.

It's from Texas Instruments pdf http://www.ti.com/lit/ds/slos263w/slos263w.pdf
>>
Using 12 v 2 a led driver to power my stepper motor, bridge and arduino. The motor is supposed to go one revolution but jerks in smaller 15 degree steps. The motor goes the full rotation with a higher current supply and even with the arduino 5v. Whats with the jerking?
>>
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Sup, I'm trying to create breakout boards for an attiny 2313 and 85 to program them with an USBasp, will this board work? Am I missing something? Also, how do I remove unwanted fill from an area inside a polygon in eagle? I don't want solder to stick to ground (green arrows) when I solder the 2313.

>>1213768
Post the motor specs? Maybe your arduino is not generating the correct waveform.
>>
>>1213768

I'm not sure what you mean by the motor going full rotation when it gets more current. A stepper motor when driven with DC pulses is supposed to take steps. If yours is a 15 degree stepper motor then if you apply the correct excitation it should take one 15 degree step and stop there.

At high pulse rates a stepper motor can rotate smoothly depending on things like load inertia; if the inertial load is high you have to start at an appropriate low step rate and ramp up to some maximum speed beyond which it will behave erratically unless you increase the voltage.

When you say it's supposed to go one revolution does that mean your control program is sending it the exact number of pulses for one revolution? and when it "jerks" does it not complete the revolution? If it actually goes the full revolution, but seems to jerk more with higher power, that is because it is going to the next step faster and is stopping there as it should. The lower power might be just barely making it to the next step so that it seems smoother.

The main question is "does it go the right amount of steps?". If it does, it is doing exactly what it is supposed to do.
>>
Hi /diy/,

I'm in my mid-20s and haven't taken a math class since high school years ago (and that was only Algebra II) but I am interested in getting into electronics and maybe building a few practical circuits and motors. What's the best way for me to get into this field with very little prior knowledge of electrical engineering? How much math will I need to know if I just want to understand and build simple circuits?
>>
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>>1213774
>>1213771
I just have the stepper motor one full rotation set up from the arduino library. When powering the bridge and motor from arduino it does go the full 200 steps (one revolution) like it should and both bridge and arduinos leds are constant. Same when i power it with my old pc power supply. But for some reason when i power them with the led driver the motor just nudges like 30 or 40 steps. Also the bridge and arduino leds just flash during the burst of movement. Bridge is L298N.
>>
>>1213776
>How much math will I need to know if I just want to understand and build simple circuits?

Depends on the circuit. Practically none for lots of digital and microcontroller work. A bit more for opamps, amplifiers, filters, etc. High level analog work can require a deep understanding of several kinds of math.

I'm average at math so I abuse AVRs and the sort of sensors and devices that work well with a microcontroller. Bluetooth, wifi, xbee, etc. can be used with no math skills at all, and you can sense things like temperature, voltage, pressure without a great deal of math, mainly multiplication or division.
>>
>>1213776
Simple DC electronic circuits don't require much math at all, multiplication and division for ohm's law at worst, AC electronics and three phase systems require a bit more math like trigonometry but it's not complicated either. Then when you get into more serious electronics design like filters or voltage converters with non linear elements like inductors you start using derivatives and integrals, but don't worry too much about this, I've build complex circuits like capacitor chargers without using complex math, nowadays you also have many circuit simulators that do the calculations for you.
Digital circuits with logic gates require logic operations in order to simplify circuits and things like that.
With microcontrollers you don't need math at all, just learn C and you're done.
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>>1213776
You kind of need some knowledge of calculus to understand how capacitors and inductors behave mathematically but the inherent principles behind them are actually quite simple and like >>1213786 said, most of the difficult math can be handled by simulation tools.
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>>1213780
>nudges like 30 or 40 steps. Also the bridge and arduino leds just flash during the burst of movement.

If it goes 40 steps properly it can go any number properly. If it is behaving erratically then it can do anything, like successfully completing four steps and then missing the next four.

A 1.8 degree stepper motor with two phases will always miss steps in groups of 4 or multiples of 4; it cannot miss just one, two, or three steps out of a sequence of 100, for example.

A scope would be awesome at this point. Or a multimeter might show that the voltage is dropping when the motor is powered. Depending on the excitation mode your L298N can be powering both phases at once which at low speeds would draw 1.7 x 2 = 3.4 amps which your 2 amp supply cannot provide.

What sort of current does your arduino provide? That spec you posted is worthless because it does not list either voltage or winding resistance. Can you measure one of the phases?

Ok, I found one site that recommends 12 volts, so your voltage is ok but your current might be low. You can configure the L298 to power just one phase at a time and it will work well with less torque, but that would involve editing the arduino code.
>>
>>1213783
>>1213786
>>1213788
That's reassuring, thanks. Do you have any book recommendations for a total noob? I looked into Getting Started in Electronics Forrest Mims III and Make: Electronics Charles Platt from the OP, would those be a good start?
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>>1213746
>where do I find that kind of info in the datasheet?

www.ti.com/lit/ds/slos263w/slos263w.pdf

Page 16 -- same pnp input structure as the LM358, expect similar limits
Page 6 -- limits specified accordingly

The traditional solution is shown at >>1213687, which of course doubles the input offset. TI specifies typ 1.7 mV, max 7 mV at 25°C and a drift of 5 µV/°C. The ST version of the LMV358 names 0.1 mV, 3 mV and 2 µV/°C while Fairchild gives 1 mV, 7 mV and 6 µV/°C.

For real high resolution ADC applications you may want to look for other components (e.g. offset and drift compensation) or deal with it otherwise.
>>
>>1213780
Stepper motors sometimes work with low voltages to limit the current flowing though them, measure the resistance of one of the coils and adjust the voltage accordingly.
If you are overvolting them the magnetic kicks might be rotating the axle all over the place.

I've found the specs on aliexpress and it says it has a resistance of 1.6 ohms, the voltage should be around 2 to 3 volts to avoid overdriving it, your LED supply is 6 to 4 times that, no wonder why it doesn't works.

https://learn.adafruit.com/all-about-stepper-motors/matching-the-driver-to-the-stepper

Also, don't run it from the Arduino's 5 volt supply, it is designed only for low current applications, don't kill your board.
>>
>>1213796
The bridge is rated for 12 volts
>>
Does anybody recommend a textbook or other resource for learning about practical electrochemistry? I'm getting somewhat interested in Li-Ions and such, but that one chemistry paper didn't really go into the practical constructions and limitations of batteries.
>>
>>1213796
>If you are overvolting them the magnetic kicks might be rotating the axle all over the place.

This is not true. If you apply power to one or both phases it has one exact place that the rotor will turn to. If it gets there quickly, it will overshoot a bit and then will be driven back to that precise point.

The only way it can misbehave is if you have a huge inertial load and you apply power briefly to launch that inertia and then remove power and the flywheel keeps turning. This is not an issue with that motor or its typical applications.

>>1213796
>I've found the specs on aliexpress and it says it has a resistance of 1.6 ohms, the voltage should be around 2 to 3 volts to avoid overdriving it,

Again this is not true. The current in a stepper winding is a function of the applied voltage, the winding inductance, the winding resistance, and the back EMF. If you drive that motor with a proper 12 volt supply at a high enough pulse rate it will not draw excessive current. The guy really needs a scope at this point, but he can probably figure it out by trial and error. His problem might be that the L298 is powering both phases at a relatively low step rate (3.4 amps possibly) and the power supply rating of 2 amps is the issue.

You are probably correct about the arduino, but since it runs the motor at all I wonder if he has some sort of motor driver package that can provide the current.
>>
>>1213798
I didn't talk about the bridge, I'm saying that the resistance of the coils of the stepper is very low, and you need a very low voltage to drive the stepper if you don't want to exceed the current limit, like 2.7 volts, if you drive the stepper with 12 volts it's going to spin all over the place.
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>>1213750
If the datasheet values look incomprehensible, you must consider a) what the parameter actually tells you, b) what is the desirable value and c) what covers the manufacturer's ass.

In this case the parameter indicates the maximum input voltage range. Bigger range is better, preferably it should extend outside the supply voltage range. However, the internal design limits the input voltage range below the positive supply. Manufacturer guarantees that all the ICs will work as long as you keep the input voltage between 0 and 4V. You can expect your typical amplifier to be somewhat better than the worst case amplifier, so typically they're ok with somewhat wider input voltage range. Thus, the typical values are below the guaranteed minimum and above the guaranteed maximum.

From the design point of view this means that if you make sure the input voltage is within 0-4V, all the amplifiers work properly. Many of them can do better, but you have no guarantees of that.
>>
>>1213805
>if you drive the stepper with 12 volts it's going to spin all over the place.

Steppers do not "spin". If he applies 12 volts to that winding the motor will step wonderfully but if he does it at a low rate it will overheat the windings. The ideal way to avoid this is with a current limiting driver. You need the high voltage to get high speeds due to the back EMF of the motor. He can drive the motor with a few volts but the maximum step rate will be pretty low, and with 200 steps per revolution, that's gonna be one slow motor.
>>
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Hey, any Germanbros here?

Do you have online electronic components retailers equivalent to Mouser or Digikey?

Thanks! (pic unrelated)
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>>1213834
There would be reichelt, conrad, pollin, bürklin, watterott and RS-Components.
None of them has a selection as big as Mouser or Digikey though.
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tfw my calculator got aids
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>>1213834
Sure, more than enough, among them mouser.de and digikey.de.
And then there's my local dealer who also has a webshop..
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>>1213859

i had a duracell like that's supposed to survive for 10 years. started leaking after one year. waiting for someone to do a class-action suit.
>>
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>>1213870
I just clipped the leads, taped the buttons and now I'm bathing the case in bicarb+water.....then I realised it's an alkaline battery durrr

Whatever.
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>>1213810
> The ideal way to avoid this is with a current limiting driver.
A viable alternative is to use open-loop control, varying the duty cycle (or pulse width) as a function of motor speed.

But note that torque will vary with mean current, while power dissipation will vary with RMS current. So to get the maximum torque without frying the windings, you want a reasonably high PWM frequency (relative to R/2πL) so that RMS current is roughly equal to mean current.
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>>1213882
>A viable alternative is to use open-loop control, varying the duty cycle (or pulse width) as a function of motor speed.

That's interesting and might work well. I don't have any stepper systems any more or I'd check it out. I used to have an elaborate homemade device that had multiple steppers working in sync to apply glaze to a piece of pottery. Tuning the ramp rates so that the motors could all accelerate together to a reasonably high speed without ever missing a step was a lot of fun.

I actually did this on a 286 PC back in about 1990. The first step was to map the surface of the vase to within about 0.01 inches, then the device would mix the colors and apply the pattern. It took a couple of hours to do one piece.

Unfortunated I have no space, so once the fun wore off I dismantled it all and got rid of it. I don't even have any of the pottery; just some blurry old pictures.
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>>1210688
>bjt is current controlled current gate
lolno
a BJT behaves like a voltage controlled current source, much like a FET
>>
>>1213908
>voltage controlled current source
no, bjt is current controlled, Ic=B*Ib
>>
>>1213882
> A viable alternative is to use open-loop control, varying the duty cycle (or pulse width) as a function of motor speed.
Of course, this is only open-loop to the extent that the motor speed is a function of of its drive pulses.

With a stepper motor, that /ought/ to be the case; if it's skipping pulses, You're Doing It Wrong.
>>
Anyone with signal processing experience?

I'm not an EE or a SP engineer, just a software engineer doing hobby shit. I have a way of getting raw RF ADC'd samples. But I want complex samples.

I see DDC is a way of doing this but you have to use an oscillator frequency centered on your signal of interest to fold your SOI back to baseband. What if you don't have a signal of interest and just want the whole spectrum and you don't want to do any frequency folding when you multiply the in-phase oscillator and quadrature oscillator?

Maybe this isn't the place to ask
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>>1213946
>What if you don't have a signal of interest
Then choose a band of interest and tune around in the IF to pick out signals, maybe?
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>>1213946
>software "engineer"
>>
>>1213946
>complex samples
what does that mean in this context?
>>1213996
go back to /sci/, kid
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>>1213946
you can't use any kind of shifing on 'the whole spectrum' because its fucking infinite. its already at low frequency and at higher frequency and all the frequencies in between. you can pick a section you want to listen to and shift it.

how does your raw rf adc work? rf signal as a sinusoid is already complex, it has an amplitude and a frequency. whichever you are measuring just measure the other one too!
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>>1213996
>>
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12V 2A AC to DC Buck Converter Step Down Isolation Power Module Supply Regulator

Can I hook these up in parallel to draw 12v 4a max?
>>
>>1214188
Most likely no, at least without modifying the control circuit.

Don't trust cheap shit power supply modules at full rated current anyway.
>>
>>1213996
gr8 h8 b8 m8

>>1213946
>complex
you mean In-phase and Quadrature?
if you have no signal of interest then you have no carrier of interest and therefore no reference against which to demodulate.
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>>1214197
So youd recommend just buy a 12v power supply or wall adapter instead?
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>>1214210
Yes, always use a power supply rated for your application.
>>
>>1209426
Anyone got arduino analog reading experience.
I want to use hall effect sensors to track something with high accuracy. The issue is that when reading from the analog pins I keep reading that you need to set at least a 1 ms delay between each pin read (different pins).
So with 5-6 analog inputs its looking at 6ms per read but Id like for it to be max 4 or 3ms.
Ive considered only using 3 hall effect sensors because of this but the result isnt as good.
Are there other things to circumvent this. Not much experience reading analog pins on an arduino so Im lost. Would an analog to digital shield help this problem since it specializes in reading.
>>
>>1214223
what are you using your halls for? generally you don't need to actually measure the output of the sensor (ADC), you just need to detect at a certain threshold. for this you'd want a comparator, but digital inputs can be sufficient if the conditions are right or you add some signal conditioning yourself.
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>>1214223
Have you just tried it without the pause? You might be able to get away with it if you don't mind losing a bit or two of accuracy.
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>>1214229
theyre linear hall sensors I need to track motion for an experiment Im doing for my modern physics lab.
>>1214232
I dont have the sensors yet. They should be in tomorrow or tuesday. Im just writing the code for now and saw how high impedance sensors like a hall sensor need a delay.
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>>1214223
well now i'm just about jizzing in my panties because this is exactly why arduino is shitty and i'm all about ragging on it.
to do adc there is only one actual adc module inside the microcontroller and it is multiplexed to the various analog inputs. part of the adc circuit is a capacitor which is part of a sample and hold circuit and tracks the input analog voltage which is isolated for converting when you are ready. changing between pins means this capacitor has to be given time to adjust to the new voltage from the new multiplexed pin.

if you had low level control of the chip and read the datasheet for the particular device you could calculate the minimum sample time for your input impedance as well as work out the acquisition time and even fiddle the clock frequency to reduce conversion time.
but you have an arduino, so you have to do what they let you.
i don't know what else an adc shield would be rather than a dedicated adc. if it has the channels and speed you need then why not?

if on the other hand you like some excitement in your life you could get a handfull of comparitors (op-amps), comb your resistor drawer throw in an analog mux and build a flash adc.
learn some skills and at the same time have an adc that will output in ns rather than ms. but you would need a few spare pins for parallel input.
>>
>>1214241
you can freely fuck with the registers while coding with the arduino ide. they only impose a startup and general loop structure on you. so you can optimize the adc.
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>>1214239
>high impedance
I think you might want to put some sort of amplifier on them to reduce input impedance and decrease hold time. A simple opamp voltage follower might do. If your max voltages don't increase beyond Vcc - 1 V or you don't mind dividing them down to add headroom, you could use something cheap and available like an LM324.
>The ADC is optimized for analog signals with an output impedance of approximately 10 kΩ or
less. If such a source is used, the sampling time will be negligible. If a source with higher impedance is used, the sampling time will depend on how long time the source needs to charge the S/H capacitor, with can vary widely. The user is recommended to only use low impedance sources with slowly varying signals, since this minimizes the required charge transfer to the S/H capacitor.
>>
>>1214241
fastest adc Im seeing is 860 samples per second. Which is fine if it means that it can read 4 pins in one sample.
Im curious about the diy adc and what it would take to get decent accuracy. Will look into it in the future.
>>1214259
As I said before reading analog inputs is something new to me, but from what I gathered that is referring to reading the same pin. Ive read that you might have to read the pin twice to get a reading if the impedance is over 10k.
I need to find more examples to understand whats going on but an external adc is probably the best solution.
>>
>>1214263
do you know what the output impedance of your hall sensor is? if the output is large enough to read from an arduino without gain then surely it has internal amplification and the output impedance is thus arbitrary, and probably not that high. i'm looking at a honeywell part now with a 10k output impedance, just as a reference.
>>
>>1214267
I bought some cheap ones from ebay but when I looked into them they were around 10k
>>
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I need help finding an IC, I want to build a synchronus buck converter with external gate drivers and mosfets. All I need is a simple IC that outputs dual PWM signals and senses the output voltage to compensate. The power management IC section on mouser and digikey is utterly fucked, the listings are all wrong and include results with integrated switches and gate drives even when you exclude them. I have spent hours trying to find a suitable IC manually but can't find anything.
>>
>>1214381
Have you tried Mouser's filtering?
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>>1214391
Yes it's hopeless specifying external switches and gate drivers does nothing, you still get ones with internal fets while ignores others without. The entire PMIC section is largely broken on both mouser and digikey. Surely there must be an IC that just outputs two PWM based on voltage feed back and a setting to select pwm freq. I can find plenty with internal switches but they don't come in the voltage range I want.
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has anyone bought cheapass electronics kits off some chinkshit sites? I've been looking to buy a breadboard, jump wires, some resistors and caps to fuck around with electronics. I'm primarily interested in making small peripherals for my Raspberry Pi.

Would someone recommend me some kits to try out?
>>
>>1214487
No absolutely not.
Think up what you want to build.
Design it and test in spice
Order the parts you need.
Things like resistors, instead of 1 order 100. It will cost exactly the same. Capacitors same thing, ceramic order 100, electrolytic order 10. You should know when to use each because you already researched it right? Transistors same thing order a handful of general purpose signal n type.
Get a few breadboards. If you can get a kit that's cheaper than buying them individually then buy it. Don't buy a kit just because its mounted on a piece of metal. Don't let it tell you how many boards you need.
Get a baggie of tactile switches with the 4 legs. Pennies each. Big bag of 3mm leds. Pick your favourite out of red or green, don't you dare pick blue and buy 100. Buy a roll of equipment wire 1/0.6 or equivalent whatever shit backwards wire gauge system you use. Pre cut and striped wire kits are a meme, practice cutting forming and stripping nice neat wires around your board.

Look for price breaks, buy in bulk, don't buy shit you don't need. Consider tax and postage.




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