Thread cracked: >>2989599>I'm new to electronics. Where to get started?It is an art/science of applying principles to requirements.Find problem, learn principles, design and verify solution, build, test, post results, repeat.Read the datasheet.>OP source:https://github.com/74HC14/ohmOPbake at page 10, post in old thread>Comprehensive list of electronics resources:https://github.com/kitspace/awesome-electronics>Project ideas:https://hackaday.iohttps://instructables.com/tag/type-id/category-technology/https://adafruit.comhttps://makezine.com/category/electronics/>Books:https://libgen.is/>Principles (by increasing skill level):Mims III, Getting Started in ElectronicsGeier, How to Diagnose & Fix Everything ElectronicKybett & Boysen, All New Electronics Self-Teaching GuideScherz & Monk, Practical Electronics for InventorsHorowitz and Hill, The Art of Electronics>Recommended software tools:KiCAD 6+CircuitmakerLogisim Evolution>Recommended Components/equipment:OctopartLCSCeBay/AliExpress sellers, for component assortments/sample kits (caveat emptor)Local independent electronics distributorsladyada.net/library/procure/hobbyist.html>Most relevant YouTube channels:EEVblogW2AEWMoritz Klein>microcontroller specific problems?>>>/diy/mcg>I have junk, what do?Shitcan it>consumer product support or PC building?>>>/g/>household/premises wiring?More rules-driven than engineering, try /qtddtot/ or sparky general first>antigravity and/or overunity?Go away
>I have junk, what do?Use it to practice soldering and desoldering.
>>2996880Eyeballing the dimensions and using the density of barium titanate (which is apparently what ceramic caps are made of)...>(40cm * 20cm * 20cm) * 6.02g/cm**3 = 96.32 kgThat picture is total bullshit, there's no way she could lift that, especially not with that grip
>>2996936If you look closely you will see that they're schoolgirls practicing board assembly using painted foam blocks and Velcro to stick them on the PCB. Also, it's a drawing and nothing is real, Percy.
been fiddling with a Wien bridge oscillator today, trying to get the amount of distortion down. -80 dB THD here, a huge improvement of my previous attempt at -40 dB or soevery now and then, modulo breadboard connection crappiness, that second harmonic is down in the noise floor, so -100 to -120 dB. the trick is to bias the JFET just right so that it only has to servo the gain in a narrow gainthere's circuits that can go as low as -140 dB but I can only use parts that are roughly 0402 size in my application. this means no LDRs
>>2996943forgot the circuit
>>2996951Put another diode in anti-parallel to D1.
>>2996953no, that'll ruin the AGC function. D1 acts to pull the gate of Q1 low when the oscillator reaches a particular amplitudean earlier version of the circuit did have an antiparallel diode, but with a 1M series resistor. this was to pull the gate voltage up slowly. putting a resistor to the source of Q1 proved simpelr
>>2996936No it's not a massive PCB, rather the girls are tiny, and maybe they're even robots. As per the square cube law, they'd be extremely strong for their size, much like insects. With one on each corner, they could likely lift that QFN, but it would be more fun to imagine them wearing hard hats and directing a crane to move it into place.>>2996951Putting a resistor in series with D1 would prevent the gain changing as quickly, and would probably reduce distortion. But conversely it would reduce your amplitude control. I've never made a sine oscillator though so I'm just spitballing.I know some people make sine oscillators using an incandescent light bulb as the variable resistance, perhaps you could use a tiny thermistor? Like 0402 or 0201, so only a few milliwatts are required for it to regulate itself.Is it for a certain purpose?
>>2996958>Putting a resistor in series with D1 would prevent the gain changing as quickly, and would probably reduce distortionnope, tried that. makes things worse>I know some people make sine oscillators using an incandescent light bulb as the variable resistance, perhaps you could use a tiny thermistor?can't really do that, because I need to keep the power dissipation low. self-heating is a concern>Is it for a certain purpose?it needs to fit in a 3 mm tube (2.5 mm ID) because reasons. power and signal goes through an RG-178 coax. it's for basedence!
>>2996960Commit the circuit to protoboard just to get a baseline. I don't trust breadboards.
>>2996961yeah I just had the same thought. tomorrow
Why am I having such a difficult time finding stereo FM transmitter IC chips on Mouser? Something like the BA1404 or NJM2035. I want to take two audio channels and transmit them over FM at low power. Just like BT FM car radio transmitters.I've looked in the modulators section, the RF transmitter section, and the audio transmitter section. Do I have to have a computer generate the signal instead?I do not have a great understanding of modulation and wireless transmission. Ideally I wouldn't need to in order to use an IC chip for the job.>inb4 FCC needs license and registration for thatLet me worry about that
Volume box done. Input jack, output jack, and a headphone bypass on a switched jack.
>>2996983>Do I have to have a computer generate the signal instead?before bluetooth, there were hundreds of FM transmitter models being soldfrom super-cheap ones with fixed frequencies, to sophisticated ones with digital frequency display, and MP3 decodingi got half-a-dozen from the thift-store for around $2 eachfind 'em on ebay, tooit's ridiculous to make your own; you''ll never match the price and features
>>2997000Still worth designing if he wants anything other than the default antenna or input filtration. Maybe he wants to add an amplifier or BNC or SMA socket, or maybe he wants to ditch the high-pass input caps and transmit a DC or very low frequency audio waveform. Or maybe he just wants to optimise the design to something with a lower noise floor.I’ve got the PCB from a cheap product (inline headphone remote) inside one of my projects, but it frequently malfunctions in ways I do not understand. Even just knowing how these things are designed and what their limitations are can be very useful.On that note, if anyone can figure out what chip is inside these apple-style 3.5mm earbuds that would be appreciated. I couldn’t find anything, so now I’ll try looking into the other end, the chips behind the TRRS sockets in cell phones, to see if they describe the protocol. Maybe there’s info in the Pinephone or other open source device documentations, or maybe there’s a relevant chip name in an ifixit teardown.
I’m not exactly an expert but I can do some arduino stuff. I gutted a broken robo vacuum and want to re-use some parts. I identified and tested most but wondered if you could help identify the others and say if/how theyre usableFirst one is the suction motor. The only motor that doesn’t start to spin when I put 12V on it, tried both polarities. It has 2 large and 2 smaller wires (I think Hall effect sensor). Does this need PWM to run? No markings visible without breaking the fan off, except ‘Nidec’
>>2997034Then there is this one. Sensor seems very simple but it’s the only sensor that comes with its own complex PCB. It used to look down at the floor, it says HTW225A but that doesn’t yield any result. What could it be?
>>2997035Finally a camera with a ribbon cable. The camera itself in the housing is a small cube shaped module with zero markings. Was wondering what to connect this ribbon to, or what kind of protocol this would be using
>>2997034I'd guess that there's a motor driver on the board, and that that's a 3 phase brushless motor. The driver would be activated by talking to it via the comms wires, maybe it's I2C or SPI or UART, or just PWM or even an analog voltage. Maybe it's like a 4-wire PC fan, and one wire is tacho and the other is PWM, maybe it just needs 3.3V or 5V or whatever on the PWM pin to turn on. But I'd hold off on putting voltage on those small signal wires especially, very easy to damage stuff.By feeding it negative voltage you probably fried the driver, but it's possible you didn't. To do anything with it, you'll want to reverse engineer that PCB, should be very feasible if you can actually get it out of that housing.>>2997035Where was the sensor? I'd guess maybe it's an ultrasonic transducer, for distance-measurement in addition to the camera(s).>>2997036That one you're either going to have to reverse engineer the camera by tracing wires back to the main ICs inside the housings, or by tracing the other side of where that ribbon cable connected to on the vacuum's main board. There looks to be 4 differential pairs, it's probably something like LVDS.Ideally you'd want to use an oscilloscope or logic analyser to see what happens on the wires as the full vacuum operates, or at least attempts to operate.
>>2997037Thanks a lot anon. I’ll try 24 and 5V or 3.3V PWM on the small wired. It seems a bit like the motor holds itself in place when applying just 24V. I’d have to break it to see the board and it may be broken already so if that doesn’t work I guess I’ll scrap it> Where was the sensor?Bottom of the machine facing down at the floor. I’m mostly curious as to what the PCB does and why this is the only one they didnt connect directly to the main board The camera ribbon is just a tiny bit too large for the rPi camera port (2 pins too many I think) but looking at the ribbon it looks like only 6 are connected (the rest looks like either ground or isolated) but maybe in missing something
>>2997000I want to integrate it into a portable music player. I could just buy some old BA1404 on eBay, and that might be the best solution. I was just hoping there is something equivalent available through Mouser
>>2997041>I’d have to break it to see the boardOk then at least do some measurements with your meter, to see if there's diodes between the input power pins (e.g. the body diodes present in an H-bridge or 3-phase inverter). And use current limiting resistors on your PWM signals (1-10k should suffice).>facing down at the floorNot sure what it would be. Maybe something to do with the charging dock? Or a sensor to discriminate between flooring types?>looking at the ribbon it looks like only 6 are connectedFrom bottom to top:>1 - GND>2+3 - differential pair>4 - GND>5+6 - differential pair>7 - GND>8+9 - vias going to other side, possibly another differential pair>10 - GND>11 - via going to other side, probably a control signal>12+13 - GNDs>14 - via going to other side, probably a control signal>15 - GND>16 - NC>17 - via going to other side, probably a control signal>18 - GND>19+20 - vias going to other side, possibly another differential pair>21 - GND>22+23+24 - NC>>2997044Gonna make it the right size to fit in a cassette deck too, with magnetic transducer pickups along the top? It's only a matter of time before someone makes an extra thin MP3 player that beams data into a CD player's optical pickup.
>>2996998And here it is flipped and mounted under my desk. Next to my audio mixer.
>>2996983what kind of range do you need from your transmitter? what kind of CPU do you have in your device? if you have a PWM channel that goes up to say 100 MHz then generating FM is quite easy. if it doesn't go that high then you can use a lower frequency like 33 MHz and pass the signal through a diode, then through a band pass filter to extract the 3rd harmonic
>>2997048Broadcast FM varies the frequency by up to +/-75kHz modulation depth. For 16 bit audio, a least significant bit would be 2Hz of modulation. To do that digitally would be extremely difficult, requiring that your PWM channel be clocked 2^16 times faster than the output 100MHz.An MCU with a 400MHz clock can produce 400, 200, 133, 100, 80, 67, etc. MHz from its internal timer/counter, it’s infeasible to generate pre-modulated FM.Instead you want a PLL. Digitally, you could hop around multiplication and division registers to create arbitrarily finely divided frequencies, but you’ll probably still get glitches. For FM, a conventional VCO is probably the best way to go. For stereo, that requires analogue circuitry to amplitude modulate the difference of the channels on a supersonic carrier, and add that to the sum of the channels, before piping that into your VCO. Seems like a fun project, but a big time sink.
>>2997050https://github.com/cnlohr/channel3https://github.com/cnlohr/avr_vhf
>>2997050>what is phase modulation
>>2997053CNLohr’s videos on generating NTSC from the ATtiny and 8266 just show him generating black and white video, which is fixed frequency.But his video on generating LoRa chirps with an ESP shows that semi-continuous frequency sweeps are possible, by generating varied lower frequencies and relying on their higher square harmonics. You could get dozens, maybe hundreds of frequencies from this technique, more than enough for a proof of concept of FM broadcast radio, could probably even make it stereo and/or dither the frequency to give a higher effective number of bits. But I doubt you’d approach 16-bit audio quality.>>2997054I’m not sure I understand how phase modulation or phase shift keying could be relevant to outputting broadcast FM from a microcontroller. Might you enlighten me?
>>2997117you can twiddle the PWM phase using the derivative of the audio signal. push the phase forward when the derivative is positive and vice versa. you can add dithering to get more bits. this probably consumes most if not all cycles in anon's CPU, unless it has more than one core
>>2997118If your PWM counter is going up 100 steps in a triangle wave, and the counter is clocked from the main clock directly, then that’s 200 different phases, which isn’t very much. It also requires that your system clock is 100 times faster than your PWM output, so it would still be infeasible to directly output that 100MHz broadcast FM signal. With downsampling techniques it’s possible.The limitations would be different to changing the output frequency conventionally, you’d get the full dynamic range up at the 15kHz range, and down at 150Hz you’d have 100 times less range. And because it’s still outputting edges synchronously with the main system clock, you still have the same fundamental resolution limit as just adjusting the counter’s output frequency. Maybe they can be dithered differently, and maybe it’s easier to subsample, but I doubt it.Some MCUs like the ESP32 have a built-in PLL piped to output pins that would be better for this than subsampling alone. You might instead be able to mess around with clock calibration registers to output a continuously varying square wave.
>>2997129perhaps generating a baseband signal and then writing a tightly optimized mixer loop that said signal is fed into could work? that is, one could use a GPIO pin as a 1-bit ADC and push SDR samples to it. such a scheme could be expanded to say 8 bits with an R2R ladderit sure would be good if anon told us what he's working with, CPU-wise
need a sanity check please, is that op amp upside down to buffer the square wave coming in at pin 9?
>>2997158>is that op amp upside downyepreverse + and - inputs
>>2997161it works either way up in Falstad, but is this one of the cases where simulation doesn't reflect reality?
Yesterday I sold my old soldering station and today I sold my hot air station. And my new ones haven't arrived yet and won't arrive for another week at least. I feel cortisol spiking, /ohm/.
>>2997158This original configuration makes positive feedback, producing a comparator with hysteresis. Any input wave with sufficient amplitude will produce a square wave output, while a low amplitude input wave will produce a DC output. In reality, if that’s a single-supply rail circuit (e.g. 0V GND to Vee and +12V to Vcc), it probably won’t work as a proper comparator. If this is intended, it’s somewhat odd to be using an op-amp instead of a dedicated comparator IC.If you flip the op-amp, it will instead act like a non-inverting amplifier with a gain of 11, and will work well regardless of the supply rails. Though if the input wave’s voltage ever goes above Vcc/11 or so, it will see clipping distortion on the amplifier’s output.Considering the input is something akin to “square raw” and the output is “Clock 1”, a digital output of a comparator circuit seems more sensible than an analog output of an amplifier. So I’d suggest the original orientation is intentional and correct.For confirmation you’d be trying to answer the questions “what task is this amplifier circuit supposed to be doing” and “are the power rails and input signals correct to facilitate this task in one of the circuit orientations”.>>2997163Use spice, or some other simulating software where op-amps have supply rails, input and output voltage ranges, and can clip.>>2997168How are you going to fix your new soldering station when it dies if you don’t have a backup?
>>2997170>How are you going to fix your new soldering station when it dies if you don’t have a backup?After I listed them for sale, I was expecting that it would take me weeks to sell. Instead, both were gone in 2 days. I recovered about 70% of what I paid for the new ones and I'm happy about that so all the hassle of not having any tools is worth it. I'm just an amateur who does it as a hobby. Anyway, poor people problems.
>>2997173Mind telling us what you sold and what you bought?
>>2997174>Mind telling us what you sold and what you bought?I sold a Weller soldering station and a Yihua hot air station. I bought replacements from China. Got a battery-powered soldering iron that uses C210 cartridges and bought an Atten hot air station.I didn't spend a lot of money and feel like I'm upgrading by a lot.
>>2997176>battery-powered soldering iron that uses C210 cartridgesHow many watts? I haven't seen a battery iron above 30W, and most of the compact ones are down at 8-15W.
>>2997199>How many watts? I haven't seen a battery iron above 30W, and most of the compact ones are down at 8-15W.28W on battery and 65W when plugged in over USB-C. Given the specs for C210 cartridges, it has enough juice to drive them well. Everything I use an iron for, this can do it. After looking at various cartridges, I went with C210 since they're like 2ohms and heat up insanely fast.Last month I was at a local makerspace to get a piece of acrylic laser cut and while there I tried few of their tools. They had few battery irons and I've been lusting over one since then. Having one less wire on the desk, especially for something I use all the time, is worth the loss of power (most of which I don't even need).But your mileage and use case might be totally different of course.
>>2997225Link? I can’t find any rechargeable irons that come close to those specs. Better not be a fanttik t1, saw a review where it was like 80C too hot.
>>2997258>Better not be a fanttik t1,kek, no. it's a (better?) version of JBC's B.IRON 100.https://en.alientek.com/Product_Details/80.htmlI bought it the moment I saw the specs. I haven't seen many reviews of it (most were in Russian I think).
Before I burn my house down, I got a 24v 600w psu who's power switch seems to have failed closed. When I push the switch to turn off power it almost springs back to the on position and even if I get it to stay in the off position its still not off and power is being supplied. I just opened this out of the box and have only hit the switch like 5 times. Is this an issue with the psu or am i being an idiot somehow. Secondly Im trying to power like 5 or 6 dc motors possibly multiple at a time but its not worth a house fire and I can get away with running two at a time. I just need to know how much power they are drawing so I can get a psu with a current limits thats just 1.25 that. I thought about just using a multimeter but the concern is that the motor controller im using might try to brake the motors and use significantly more power during that time. Should I get watt power meter plug or is there something more inline I can use besides say an oscilloscope .
I think I worked out why my board (once again) doesn't work - it's not going to go very well sending +12 V signals into a chip powered off +5 volts, is it.This is a stupid error from when I was translating my breadboard prototype into a schematic, but it's got me wondering, how do you guys do it? How do you make a schematic and order a board that works flawlessly the first time around, with no mistakes?The best plan I have going forward is to build the prototype, finalize the schematic, and then re-build another prototype from scratch exactly following the schematic that I've made, that would seem to be a good way to catch errors.Some days I think I should have just stayed as a Python coding babby rather than trying to wrangle actual electrons
>>2997261Damn that looks nice. Might buy one for my brother, he doesn’t really like his current iron.>>2997280It’s not a software power button? I’d disconnect the thing from mains and measure continuity through the switch. And replace the switch anyway because switches are cheap.Are they brushed DC motors? The most they’ll ever draw is their stall current, which you can trivially calculate by measuring their DC resistance. If it’s below a few ohms, you’ll want to use a test current of 0.1A or even 1A. Or power it up with a low voltage, clamp the output shaft so it stalls and measure the stall current there, and calculate the DC resistance from that. The same sorta applies to BLDCs.But often these stall currents are stupid high and you never want to pump that many amps into a motor in the first place, at least not for more than a second. So instead you should be looking at a motor driver that measures current and prevents stall and short-circuit conditions from frying the motor. If you want to use a simpler motor driving scheme like simple MCU-controlled PWM, then I’d just look at the motor datasheet, there should be a continuous current rating. If you can’t find a datasheet for it, look for cheapish brand name motors of equal dimensions, voltages, and speeds.>>2997298Yeah analog switches are strange, you should familiarise yourself with the internal transistor diagrams of parts you don’t understand.I design a schematic first, it helps me organise my thoughts. Anything I’m unsure of I’ll simulate or breadboard, but just little segments, not the entire circuit. If it’s just something like not knowing a resistor value, I’ll leave testing that to the final build. Be that strip-board or a fab-house PCB. When getting boards manufactured, I’ll leave uncertain parts as THT, with jumpers and spare footprints as needed. Even if I’m getting SMD assembly. Often I’m not forward thinking enough and have to do bodges or board revisions.
>>2997298>how do you guys do it?we were all noobs once, sticking toy motors into 120V socketsbut we learned from our mistakesso, after 20 years, we are now godlike: making 10% fewer mistakes than when we were noobs
>>2997316>Might buy one for my brotherWait for my review. If it's any good, I'll let you guys know. I still think that getting that SI012 Pro Max is a much better deal and a much more capable iron (it can def solder XT60 connectors which this battery one will probably fail at). More versatile too. If you don't mind a wire, it's a much better buy too. With that soft liquid silicone 240W USB-C cable, it's an unbeatable setup.
>>2997320Why the Pro Max? Isn't it just a Pro with RGBs? Or is it capable of 100W while the Pro can only do 65W? I have a Pro, but only 8 ohm T12 tips, not the lower resistance shorter TS-style tips (second from left) that Sequre call "SI", but I've also seen called "ST" by others. I wonder if an Si012 Pro will output 100W if I get a lower-resistance tip into it?This picture also suggests it works with the SH72-style of shorter T12 tip (or T65-style), but they have a collet flange further up than a TS and further down than a T12, so I can't see how they'd seat properly. They only have two sets of electrical contacts from what I can see, so I think you could only use it with these SH72-style if you locked it in place with the M2 screw. Doesn't seem ideal, I'd like it if they made an iron with three sets of contacts. While the TS and SH72 contacts would probably be too close together, you could make their flange sit at different depths since the TS tip flanges are much wider.Anyhow, my brother specifically wants a battery iron (he already has a T12 station that runs on an M18 battery), and his birthday is in a month.
>>2997336>Or is it capable of 100W while the Pro can only do 65W?Correct. Pro Max can do 100W and Pro caps at ~65W. A different tip won't help you reach 100W with Pro.That battery iron will never be as versatile as wired irons. It's OK only for light hobby use with SMD and small THT components. They're definitely not good for an 8hr job type work since they last less than 40min on a full charge and take 9hrs to recharge. If you do some back of the napkin calculations, you can theoretically remove 8-9 large caps before it';s empty. Yeah, you can use it while plugged in but then you have a shitty wired iron.Get him a SI012 Pro Max and he will be much happier if he's a semi-pro.
>>2997339>A different tip won't help you reach 100W with ProConsidering it's 25V maximum, you're not getting above 78W with the DC jack, or 50W with USB PD, with 8 ohm T12 or TS tips. Only with the "SI" tips can it draw enough power.The Pinecil website describes TS tips as having 8 ohms, and the shorter ST tips as having 6.2-6.5 ohms. 25V @ 6.2 ohms is 100W, so I'm guessing the SI tips from Sequre are the same. Sequre's website describes the SI tips as "max power 100W", with no such labelling for its TS and T12 tips.That also means that with 20V PD on the Si012 Pro Max you're getting no more than 65W. I'm wondering what would happen if you put an ST/SI tip into a non-Max Si012 Pro. Would it PWM itself to limit power to 65W? Would it assume it's drawing less power than it really is, and force a 65W supply into hiccup protection? Would it detect a faulty tip and not heat up at all? Would it draw too much current and damage itself?Hardware wise, what could the difference be? Different PD negotiation chip or beefier power MOSFET, that's all I can imagine. And there might be no difference in hardware at all. There probably is software difference though.
>>2997351>'m wondering what would happen if you put an ST/SI tip into a non-Max Si012 Pro. Would it PWM itself to limit power to 65W? Would it assume it's drawing less power than it really is, and force a 65W supply into hiccup protection? Would it detect a faulty tip and not heat up at all? Would it draw too much current and damage itself?It PWM-limits itself based on calibrated resistance, not a 65W hard wall limit.I don't know about USB-C PD but I'm pretty sure that if you connect it to a 4S or 6S LiPo it would discharge massive amounts of current without caring about a 65W limit... and probably fry the P-MOSFET.>Hardware wise, what could the difference be? Different PD negotiation chip or beefier power MOSFET, that's all I can imagine. And there might be no difference in hardware at all. There probably is software difference though.An updated PD controller and software of course.BTW, It supports IronOS and devs got the scehmatics for it: https://github.com/Ralim/IronOS/issues/2010
>>2997361>BTW, It supports IronOS and devs got the scehmatics for it: https://github.com/Ralim/IronOS/issues/2010Oh huh, didn't see that on the IronOS homepage a year ago.Looking now, my Si012 Pro has the same PD controller IC and same MCU, just the board is the V1.4 not the V1.5. Its MOSFET IC can handle 4.9A which is more than enough, I may try to flash IronOS onto it using that .hex file, and get an ST tip to test with. Having a bit more grunt could be handy. If that bricks or fries it, then all the more reason to buy a Pro Max.Additionally, that Pinecil page says the following:>Older Pinecil V1 can not use the short tips until firmware code is written to enable manual selection of 6.2 Ω or 8.0 Ω tip>Only the V2 model has the hardware to auto-detect the two kinds of tips short 6.2 Ω or regular length 8.0 Ω>If you would like to help with the code, see GitHub/IronOSSo it seems possible that the Pro Max is equipped to measure tip resistance while the Pro is not.
>>2996960updooted>25 BOM items>28.5x2.3 mm>castellated "fork" for soldering the coax shield tothe one complication besides the edge plating is that I need the vias filled. but at least I got away with not having to put those special vias-in-BGA-pads
>>2997402>2.3 mma wien bridge oscillator that fits in my pee-hole?i'll take a dozen, pls
A couple of horrible bodge wires later and my board works. But I wonder if I am setting myself up for a gradual failure over time, so would appreciate some advice.I am converting a sawtooth wave to a pulse wave with a comparator, so the op-amp is swinging between max and min voltages, -12 and +12. Elsewhere in the circuit, I want to send only the positive half of that pulse wave through an analog switch, which can't handle the negative part (it is powered between +12 V and GND).So after buffering the pulse wave at U1C I pass it through diode D1. This gives me the expected positive-only square wave for the analog switch and for a flip-flop frequency divider. But when the output of U1C goes to -12V, will I develop a slightly negative voltage at the GND side of D1 due to the diode drop voltage? Could this damage the flip flop and switch by exposing them to a slightly negative voltage?Please and thank you anons, I am so close to completing this project.
>>2997471I was so close to getting it right...thank you to the anon that recommended that desoldering alloy, it allowed me to easily remove the CD4053B that I cooked by powering from +5 volts while it received +12V input signals
>>2997471That diode won’t have enough leakage to cause the voltage to go significantly negative. Maybe a few mV, it’s only an issue once you get into the realm of 0.7V, and even then it’s current limited.Also shoulda used LM311 comparators for their intrinsic speed and level shifting capability. TL074s have ok skew rate for an op-amp, but they’re just not designed to be used with positive feedback.
>>2997475In a previous design I was using an LM393 comparator to get the pulse wave from the saw. I can't 100% remember why I removed it, but I think it was more convenient to use the TL074 op amps because there are plenty else on the rest of the board so it saves having a separate kind of dedicated comparator IC, which I would have to waste half of.This is just for audio frequencies up to about 2.2 kHz, so even if the TL074 isn't ideally suited, I can still get away with using it, right?
>>2997479Depends more on how fast you want that edge to be, but it’s probably fine. You might be able to add diodes to stop it from saturating itself too much.
I have a USB powered fan and I want to put in a speed control for it. Do I just wire in a pot in series? What values? Logarithmic or linear?
>>2997543You should use a PWM controller.
>>2997509>stop it from saturating itself too muchIs that a problem?I am going off of textbook understanding and simulations, but I know that doesn't necessarily capture every real world consideration.
>>2997546I've been doing some more reading and it looks like that design is FUCKED UP and I should use a proper comparator instead
>>2997543>>2997545I know this is /ohm/, but you can get dirt cheap USB PWM controllers from China all day long. There's a common "fan governor" with a pot on the side too, but that one just varies the voltage from 2.5-8V.
>>2997546It’s not going to damage anything, it would just make the response time of the op-amps a bit faster, maybe.
>>2997048I want 88MHz to 108MHz transmitting stereo audio.I'm making a portable music player. The intent is to use the RP2040. I plan to have a bluetooth transmitter as well.I found this pre-built circuit that does exactly what I want. Is there any reason I shouldn't use it?https://www.alibaba.com/product-detail/VMR6512-Hi-Fi-FM-Transmitter-Integrated_1601591382662.htmlWith this module I can even have the radio transmitting different audio tracks as the bluetooth and headphone port. Could even have the USB-C port outputting a different audio too.I can simplify the design and make my own transmitter later on. I just don't have the understanding of frequency modulation to do it right right now.
>>2997604 (me)There's also thishttps://ja-bots.com/wp-content/uploads/2026/01/KT0803L_V1.3.pdf
>>2997604Both those modules look good. I’d go for the first one (not necessarily from alibaba) and feed it digital audio, as that removes an unneeded DAC->ADC conversion.FYI, your MCU of choice may struggle with some audio formats, both for speed and RAM. Lossless and MP4/AAC especially, but even MP3 may pose a challenge. MP3 players from 10 years ago likely have more power than a 2040, at least in the narrow domain of audio processing.
>>2997546 (me)>>2997552 (me)I breadboarded an alternative design for my saw -> square wave with an LM393 comparator and it works. This keeps everything in the positive domain, don't need to worry about the diode, etc, and the edges seem sharp enough to drive the flip flop as a frequency divider.This should be a lot better, right? I honestly can't remember how I convinced myself this was not the way to do it. I'm sure I was previoiusly running into problems with the sharpness of the edges.
>>2997624Simulators are a plight on education. They invite people not to think, not to learn but instead just 'simulate' something without understanding how the simulator works, what limitations result from the inner workings and quite frankly without an idea what 'question' they are even 'asking' the simulator.This simulator is one of the worse offenders, as it seems to integrate several elements of the equivalent circuit of a real part into a symbol that is commonly associated with the ideal part.To begin with: What do you expect to happen at a node that is connected to a fixed voltage source and a (presumably voltage) signal source?You will find more value in reading about the basics of electrical engineering first and then look at circuits that are commonly employed to achieve what you want, conduct your analysis using oen and paper. You might find more value in analysing circuits made up if discretes only first, before checking how ICs might be employed. Once you understand the underlying principles and you have very specific questions regarding performance, stability, losses etc. then use a SPICE simulator and model relevant parts of your circuit.
>>2997626Learn how transistors work, but only to interpret the input and output sections of IC internal equivalent schematics. Op-amps are a more ideal and beginner friendly way to learn about analog circuitry. Learning about proper biasing and impedance problems can wait a little.
>>2997614Thanks mate. I expect the first iteration will be more for me to figure out how to make it right. I'm not too worried about getting it all right now. I'm mainly using the rp2040 because I'm familiar with them and have them on hand. Likely I'll change to the ESP32 or something and that should allow me to simplify a lot on the device
>>2997543Honestly a pot might work for a little DC fan. So long as the fan is sufficiently low powered such that the pot doesn't get roasted. Takes math to calculate the resistance though, and it depends on the current draw of the fan. Be easier to have a voltage-dividing potentiometer + an emitter follower, or a current-limiting potentiometer + a current amplifying BJT.
>>2997653>Honestly a pot might work for a little DC fannopeordinary pots are rated 1/8-th or 1/10-th wattno fan is so weak that a pot would survive unless it was wire-wound, or packed in dry ice, or held under a witch's tit
>>2996880Hi,I'm relatively new to electronics. I've been doing security research for a decade and only in the past year had an opportunity to work on a project and develop attacks on a HW piece of tech. I got myself a logic analyzer and learned how to use it and got good at it. Anyway, I have some time off this summer and would like to build my own electronics "lab". I have a soldering iron (crappy one) and a Saleae logic analyzer. That's all. At work I had an oscilloscope, DMM, microscope etc.Since the OP post has no actual equipment recommendations (a big omission IMO), maybe someone here can recommend me some tools. I'm not interested in bottom-of-the barrel stuff but also not the expensive shit that only the corporations can buy. Can someone recommend me a:-DMM-Oscilloscope-Soldering station-Hot air station-Microscope-Bench power supply-Hand tools: tweezers/screwdrivers/pliers-Wire strippers-Board holderAnything else I'm missing???Thanks in advance!
>>2997626I think you are hinting at the fact that I was missing R5? I chose R76, R75, R5 so that when the LM393 output goes high impedance I can't develop more than +5 volts at pin 3.
>>2997665There are so many products available in different regions it's hard to recommend anything specific. Instead of buying a piece of gear that you think you might need, just buy gear to solve problem you're working on. It's pretty useless to, for example, buy a 30V 30A power supply just to find out that output switching noise is messing up your sensitive circuit. Price is also sometimes not a good indicator of product quality. Sometimes cheaper option works better in specific applications than expensive one.
>first attempt: shit's broken>attempt to diagnose, isolate subcircuit>desolder IC and find one completely shot>/ohm/ points stuff I overlooked>squeeze in a few resistors>resolder everything>virtual ground still pulled down to the negative rail by *something*I want to fix this and get it working so bad, but fuck me I'm losing my sanity here. Wish me luck.
>>2997658Worst case it drops half the power. If it’s a little 30mm fan it’s fine, but a 120mm definitely not.>>2997675That works? Doesn’t the LM393 pull its output hard down to your negative rail?Also I’d be using a Zener to ensure its voltage remains under 5V instead of resistor tuning, as that allows me to more easily tune the other resistors.>>2997729Did you breadboard it beforehand?
>>2997731>That works? Doesn’t the LM393 pull its output hard down to your negative rail?Yes, but the LM393 is connected between +12 and ground, so it gives me a square wave at positive voltages only that the flip flop can handle (which is also wired between +12 and ground).Measuring the point between "PWM" (the DAC input) and R77 on the breadboard only ever shows me the voltage at which the DAC output is set, so I think I will be safe.
>>2997700>Instead of buying a piece of gear that you think you might need, just buy gear to solve problem you're working on.Good advice but not in this case. I can't do much without a DMM, oscilloscope, soldering iron etc.
>>2997746Well you could start off by explaining what you’ll be using the tools for. Speed and memory of the scope, power and size and portability of the iron, specs of the DMM, they depend on what you need to do with them. I’ve got two of each of those with different use-cases.
>>2997731>Did you breadboard itYes, of course, except for all the bypass caps, that were suggested by /ohm/ as I was about to solder, so I quickly threw them in. Also, some subcircuits were breadboarded separately for clarity. The only difference I had was the virtual ground being provided by an opamp on the breadboard, whereas the perfboard version has a simple voltage divider. Thing is, the virtual ground is hooked only to positive and negative through the bypass caps, and to opamps/comparators' inputs, so I'd expect it to not drift too far off target even with a simple divider due to the almost-zero current it would end up conducting. At this point either another opamp is shot (idk how they could die just like that), or I fucked up the schematics.
>>2997753You’ve triple checked your pinouts? Yeah all I can suggest is socketing your op-amps so you can swap them if needed.
>>2996880why is this dumb bitch pointing at resistor pads when they're carrying a cart full of capacitors? there's two pads right there that need caps.fucking dumbass normie artists
>>2997788Follow her pointing arm in her shadow, it's pointed downwards but only shallowly. The target of her pointing is off-screen, possibly a cap connected to U7's 7th pin. C50 and C51 aren't necessarily the same size capacitors as C49.
I managed to leave a nasty scorch mark on my desk. I need a soldering iron stand.Is this a good one? What do you guys have?
>>2997820>What do you guys have?i like this one coz it leaves the hot bits completely uncoveredany faggits hanging around my workstation will burn themselves, their pants or their expensive winter coats as they peer into my workteaches 'em to stay the feck away
>>2997822Kek, nice. I live alone so I have diff kinds of issues. Also, my desk is wobbly so I'd like something firmer. Also, how do you clean the tip on that little sponge? I;d prefer a bigger sponge so it lasts longer.
>>2997788>triple dubs wasted on low tier misogyny>against 2D no lessI hope you get better anon. It took me a long while, but if I can do it anyone can.>>2997820Pic related is great. Very stable, and using the brass sponge won't thermally shock the iron tip.
>>2997827>Pic related is great. Very stable, I like it! Any idea where to find one of these things?>and using the brass sponge won't thermally shock the iron tip.I had no idea about this. I've been using a wet sponge for like 2 years. I did some searching and you're right. i've been doing it all wrong.well, I can't find any iron stand without a sponge. since sponge is actually bad, I don't want a compartment for it at all. I did find this but you need a 3D printer for it.
>>2997845You should still use a sponge to clean the tip when you finish working. Then tin it with fresh solder and turn it off.
>>2997845The one he posted is specifically designed to work with T12 soldering stations, some irons, especially non-temp-regulated irons, may be too thick to fit.I’ve used copper wool and wet sponge in the past, I don’t really notice a difference in tip longevity. Wet sponge seems to leave the tip cleaner, though my copper wool probably needs replacing.
>>2997845I got it on banggood when I got the whole setup a ksger T12 and ksger SMD station i.e. the hot air gun, but it was a not insignificant number of years ago. It was all cheap, but it all works (mostly: I had to isolate the ground of the hot air because the heating resistance expands and shorts with the metal jacket which is grounded). The brass sponge holder was sold separately, and I did glue a rubber mat underneath the base, for added grip and reduced surface wear.
Is there a good list of component abbreviations for printing on PCBs? Like R for resistor, C for capacitor, etc.?
>>2997892https://resources.pcb.cadence.com/blog/2023-identifying-electronic-components-on-a-circuit-boardbut best to follow up with an AI query coz it's more messy than thatdiff people use diff letters, and there's often 2 letters for the same componente.g. a chip could be an IC or a U
>>2997892https://en.wikipedia.org/wiki/Reference_designator>>2997912And a voltage regulator could be IC, U, or it could be VR. But I've also seen VR used for variable resistors. There are formal lists, but they're not always adhered to.
My Sugon A9 arrived. It uses T210 tips. These things are ridiculously small. LOL. When you see pics online or the reviews, you have no idea about the actual size. They have no thermal mass whatsoever. Yeah, don't expect this size to be a general iron. T245 is probably a better choice if you need that.
>>2997665Ok, I'll give it a try, so at least you've got a starting point>-DMMFluke is usually the corporate way to go. And for a reason. They are reliable and good but you'll also pay for the brand. Personally I prefer Brymen. You'll pay half the price for 2 times the features. I've got a BM867s and I'm happy with it.>-Oscilloscopeno cheap recommondations on that part. Good stuff from work for the price tag of a new car is probably too expensive.Personally I've got a Siglent SDS 1104X-E. It is decent but I did not push it far, so who knows. You can hack it though:https://www.eevblog.com/forum/testgear/unlocking-siglent-sds1104x-e-step-by-step/msg3344060/#msg3344060>-Soldering stationI've got myself a "cheap" JBC station. And I don't want to use anything else. Used an old Weller at work and switching tips is just a pain in the ass.>-Hot air stationPersonally I don't have one and only ever used it at work. Don't know the brand but it was pretty old anyway. JBC makes the too. If you want to sell your kidney.>-MicroscopeI don't use one. I've got myself a baseball cap and ghetto-rigged a bracket for different magnifying glasses to it.>-Bench power supplyI've got a single channel and a dual channel digital power supply from Korad. Fairly cheap and I had no problem with them so far.>-Hand tools: tweezers/screwdrivers/pliersKnipex for pliers, Wera for screwdrivers. And I've got a chink no name repair kit for smart phones.>-Wire strippers95% of the time I use a pair of side cutters. Just get good.>-Board holderI think I've never used any professinal dedicated board holder>Anything else I'm missing???If you are working with anything that's connected to mains, so 110V 220V 230V 400V etc. (if you are not a professional you shouldn't) a isolating transformer can safe your life.A desoldering pump. Some use a big ass station. I feel very comfortable with using the small syringe like thing. And it costs almost nothing.Hope this helps
>>2997980To be fair T12 tips are stupid long. What’s the beefiest tip you can get for a T210? Is there like a D4? I’m considering getting one. I saw what looked like a D4 in the “C210-007” size, but the legend said it was 2.3mm not 4mm, man that scale messes with you. I’m going 210 because that’s what battery irons are using, not because I want to work on fine things.
>>2998003>To be fair T12 tips are stupid long. I'm not sure what they were thinking. Probably to give it some mass for thermal inertia?>What’s the beefiest tip you can get for a T210? I think it's K. It's like 2mm wide.>Is there like a D4? No. There's like I, IS, K, KU. That's it.?I’m considering getting one. I saw what looked like a D4 in the “C210-007” size, but the legend said it was 2.3mm not 4mm, man that scale messes with you. Yes, when you see these tips on YT or in images, they look huge. They're so damn small.Here's a comparison... it's much smaller than a ballpoint pen. T115 is even smaller... like 2/3 of the size of T210.>I’m going 210 because that’s what battery irons are using, not because I want to work on fine things.That's a silly reason. It will sit on your shelf collecting dust. You won't be able to remove even a through hole capacitor.I got the new station for phone repair. I've been buying broken phones and fixing them and selling them. I needed something for fine pitch SMT.
