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askelectronics
Ask Electronics coke38 2 days ago 100%
What's the best way to add a battery like device to a dynamo light

Hello everyone, I bought a bottle dynamo for my bicycle with a rear and front light. Though I have one little tweak that I would like to add and that's a way to keep it light up for about 1 minute (at least 30 sec) without pedaling. I thought of putting a capacitor in the circuit to store some energy but I would like what do you all think of it ? Thank you for your time and have a nice day you all !

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Ask Electronics fell 7 days ago 94%
Can I charge a 19V laptop from multiple USB ports?

Can I charge a 19V laptop from multiple USB ports? My laptop's charger is rated at 19V 2.1A. I was wondering if it would be possible to build an adapter which would allow me to charge it from a power bank, even if just slowly or via multiple USB ports. I know you can buy adapters which utilise USB power delivery, but most outlets and powerbanks don't have PD yet. [@askelectronics](https://discuss.tchncs.de/c/askelectronics) [#AskFedi](https://ma.fellr.net/tags/AskFedi) [#Electronics](https://ma.fellr.net/tags/Electronics) [#DIY](https://ma.fellr.net/tags/DIY) [#USB](https://ma.fellr.net/tags/USB)

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Ask Electronics Shadow 1 week ago 94%
Schematic problem - It gets hot and smells like burning

I've been messing around with circuits my entire life but this design was time sensitive and I've never done my own PCB designs before, so I hired someone to put this together. After getting some test boards, when I plug them in the charger chip gets very hot and smells like burning.... Circuit is just a simple li-ion usb charger and a switch. I've gone through the datasheet for the bq25302 more times than I can count and I'm missing something obvious here. Using it just for delivering power seems to work fine, the problem is only when charging. I do see R6 + R7 off TS don't have the recommended 10k values, but I don't feel like that would cause what I'm seeing. This is being connected to a 21700 lipo. Someone mind lending me their eyes please? bq25302 datasheet - https://www.ti.com/lit/ds/symlink/bq25302.pdf ![](https://lemmy.ca/pictrs/image/e41d7870-52b9-4242-a991-8583d3d6e044.png)

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Ask Electronics leisesprecher 3 weeks ago 96%
How much current can I safely pull from an ESP8266?

I asked a while ago, how to build an automatic light switch and finally got around to actually building it. My board is an ESP8266 mini D, and ignoring all the sensor parts, my problem right now is powering the actual light. It's just a small LED array and I connected it directly to the 5V and GND pins (controlled via a transistor). Measuring from the wall (so including the PSU), this whole setup pulls about 3W (so far expected), however, one small component close to the USB connector gets uncomfortably warm, and I'm not sure, whether that's ok. The hot component is one of the two small thingies circled in the picture. I thought the 5V get pulled directly from the USB plug, so I'm not sure, why there is any circuitry involved.

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Ask Electronics cvieira 3 weeks ago 100%
Is there such a thing as an automotive relay with no resistor?

I've been trying to solve an automotive electronics problem for several weeks now, but everyone I've spoke to can't seem to come up with a solution. In brief, I'm trying to add a relay in-line with the horn switch in my car, such that I can close my own circuit when the horn is pressed, without affecting the existing horn circuit in the car. I had some JD1912 12V relays left over from a previous install, so I tried to use those. (Relevant image: [Diagram](https://aampglobal.zendesk.com/hc/article_attachments/360052933191/mceclip0.png)) First, I placed connected the trigger wire (pin 86) to the the wire coming into the horn switch, and the ground (pin 85). The relay triggered when the horn button was pressed as expected, but this also caused the actual car horn to sound continuously. Presumably doing this was enough to give the factory horn relay enough current to close. Next, I tried placing the relay in series with the horn switch by splicing the wiring heading into the horn switch, and connecting the relay (pin 86 and 85) in line. Once again, the relay triggered with the horn switch as expected. However, this time, the actual car horn didn't sound at all. The best I can work out is that there's a resistor in-line with the relay trigger (otherwise connecting it straight to ground would cause a short, right?) However, that resistor is just enough to allow the factory horn relay to trigger when connected to ground. The way the car is designed, I can't splice into the wire coming out of the switch to detect when the horn is pressed, since it's a shared ground with other components. My question is, is there such a thing as a relay with no resistor? Essentially all I'm looking for is a component that will "detect" current on the horn switch wire, and close a separate circuit. I'm not sure if a relay is even the correct way to go about this. Hopefully you guys can point me in the right direction.

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Ask Electronics diyrebel 3 weeks ago 92%
[solved] help needed to understand this diagram of a water flow sensor (from a boiler)

cross-posted from: https://lemmy.dbzer0.com/post/26703241 > This diagram is from the service manual of a combi boiler. It’s a flow sensor which detects whether hot water is running, which is then used to trigger on-demand heat and switch a diverter to take radiators out of the loop. > > In English, the diagram shows: > * X ⅔ red wire (+5V) > * X 2/2 black wire (ground) > * X 2/6 green wire (signal) > > I need to know what those fractions mean. I took the voltage measurements in this video: > > * https://iv.ggtyler.dev/watch?v=d8ucufoyUlQ > > I cannot necessarily trust the model in that video to have the same specs as mine. My voltmeter detected 4.68 V on the red input wire showing that the sensor is well fed. The green “signal” wire is supposed to be 0 V at rest and 2 V with water running (or I think the reverse of that is used in some models). In my case the green wire is ~1.33 V at rest and ~0.66 V when water is running. I need to know if these readings are normal as I troubleshoot [this problem](https://lemmy.dbzer0.com/post/26529192). update --- [@unexposedhazard@discuss.tchncs.de](https://discuss.tchncs.de/u/unexposedhazard) and a couple others gave the answer I was after. Then [@tofubl@discuss.tchncs.de](https://discuss.tchncs.de/u/tofubl) helped solve the underlying problem. The theory that the sensor was fine but the board was not drove me to test the sensor in isolation. The sensor gave correct output in isolation. Then I connected it back to the motherboard to retest and reconfirm that it’s still broken. But it actually worked. The hot water suddenly and mysteriously works now. I guess the act of draining the water and unplugging the connector then reconnecting and repressurizing caused it to work. It may be temporary, since in the past it was hit or miss whether it would work.

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Ask Electronics acannan 4 weeks ago 100%
How do I select a transformer for superhet?

I've recently been learning about superhet and frequency mixing and wanted to start tinkering. Specifically I'd like to try using two heterodynes in series to first frequency shift then uninvert the original audio, sort of like an analog frequency shifter. To do this, I'd need a frequency mixer. I've been looking at a ring modulator (like https://upload.wikimedia.org/wikipedia/commons/1/1b/Diode_DBM.png) which should require 4 shottky diodes and 2 center-tapped transformers. I've had difficulty locating an affordable transformer, with good enough fidelity for audio, that also includes a center tap. I have a few questions: - Where can I locate affordable, good-enough-for-audio transformers? - Is the ring mod approach good enough? I see there's also a gilbert cell. - Any general advice for someone just starting a project like this? Thanks!

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Ask Electronics m0darn 1 month ago 87%
DC motor speed control

I'm trying to achieve variable speed control on two brushed DC motors powered by a 3s or 4s LiPo battery (~12V or 15V). This is for a nerf blaster I'm modifying, which is why I'm not using a pre-made speed control ie I want control over the shape/layout. I'd like to vary projectile speed with a thumb knob. I just finished watching ElectricMonkeyBrain's YouTube video on the TL494 PWM chip. I was initially planning to vary the duty cycle with a potentiometer on the chip's control pin, to get a PWM signal and feed that into a MOSFET. But in the video he mentions that the chip has an integrated over current protection function. Ie the chip will monitor the voltage across a sense resistor in series with the load and will kill the output if the sensed voltage/current goes above a reference voltage It occured to me that I could actually adjust the reference voltage as a way to control the motor speed. Would this be a better way to achieve speed control and protect my motors/battery? Or is it a terrible idea altogether.

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Ask Electronics Rolive 1 month ago 100%
Schematic review

Hi there The purpose of this schematic is to control a DC motor that runs at 8V max. That is why I chose 4 N-channel mosfets in the H bridge. P-channels would not fully activate at voltages above -10Vgs but the N-channels can handle 18V at the gate. The 5v switches represent an Arduino's digital output pins. One to turn forward, one for reverse. To prevent a failure scenario where both pins are HIGH I added a transistor that prevents current from flowing through the optocoupler on the second half bridge. Does this circuit make sense? I'm not an electronics engineer, just a hobbyist and have doubts about how effective the gate driving circuit is of the mosfets. Thanks!

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Ask Electronics leisesprecher 2 months ago 100%
Simple light-sensitive light switch?

I'm trying to build a very simple, stupid light switch for my grow light. Essentially, I want to turn on the light, if it gets too dark outside, so that my plants can survive the northern winter. Since I'm a software guy, my first thought was an ESP32, but that seems excessive. My current approach would be something like this: https://www.ebay.com/itm/313561010352 In conjunction with a relay, both powered by a USB-PSU. If the light level is low enough, the logic DO pin should send a signal and that should be enough to trigger a small relay, so that the relay then closes the circuit to switch on the lights. Is that idea completely stupid? With electronics, I'm usually missing something very obvious. The lights themselves are already just usb powered and only draw 5W, so that shouldn't be problem. What I'm concerned with is the actual switching. Is the logic signal "strong" enough to activate a relay? Would simple transistor maybe sufficient?

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Ask Electronics john89 2 months ago 100%
How can I add wireless functionality to a simple electric motor?

I have one of those basic motor kits you can buy off of Amazon. I was wondering what steps I should take to make it so that I can turn the motor on/off with the press of a button, wirelessly. I'm still very new, so any information you can offer no matter how basic will probably be useful to me.

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Ask Electronics ilovededyoupiggy 2 months ago 100%
Ploopy mouse movement is laggy, what can I do?

I built a Ploopy mouse yesterday. All the buttons work, and for the most part it's fine. But the movement is on and off laggy. Sometimes it works great, even faster than what I had before, and then it just stalls or stutters and slows down for a several seconds. I've tried a couple different USB cables, I've taken it apart and tried to reseat everything, I took the optic piece off and tried to blow out any dust that may have been in there. But it's still on and off laggy. Happens in windows and Linux both. This is only the second thing I've ever soldered, and I'm sure I did a pretty trash job of it. The board is mostly done but you have to solder the optical chip in at build time. Could that cause it to be laggy like that? I don't see any pins accidentally soldered together, there's separation between each soldered lead, though I definitely can't do the nice pretty little dots, they're ugly as hell. They've provided instructions to build/update the firmware, could that help maybe? Just wondering if there's any other ideas to help fix this? If I knew it was a legit bad board or something I could maybe go back to the seller and see about getting a replacement, but I'm afraid my soldering could be at fault in which case I don't want to make that his problem. So I'm hoping someone here may have an idea. I love the idea of this diy 3d printed mouse, just hoping it wasn't a $100 mistake. Thanks in advance.

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Ask Electronics aaaaace 2 months ago 100%
Anyone take a Bluetti solar panel apart?

I have a foldable 120w one with 4 panels in sewn cloth. Gust blew it and the little plastic anti-tug box broke so wires could move. Still worked, but one day the watts were halved. Examined wires closely, not easy because most of that little protective box still in place, but it looked like they twisted around each other in there, so I untwisted and glued anti-tug fitting to case so it can't turn again. Today broke two mounts of the little box so I can see wires clearly, two stranded leads with what looks like a can cap in between and the remains of a foam strip that looks like it went in between. Still puts out half wattage at about 24v, but I'm wondering if wires under the fabric case are disconnected. It used to put out more than the rated 120w, I've seen 138w on the battery boxes meter. My thinking is either open the case seam to see in, or assume a panel or two shorted and are lost anyway, leave alone and be happy it works at all. One thing I don't know what happens when solar panels short, if that's what happened. I do have a DVM and could check resistance, but without disassembly it would be cumulative. Or the twisting could have disconnected one or more panels, they're supposedly wired in series and its putting out like it would on an overcast day. In which case I might be able to reconnect them. Bluetti is nice enough superficially but I'm sure I'm unlikely to get tech info out of them. They're very Apple-like is dealing with consumers. (BTW, they will sell your email address to multiple marketers promoting "sales" of bluetti products after a purchase. Not a lot, but the sender addresses are always different.)

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Ask Electronics Grumpydaddy 2 months ago 96%
how the heck does FM work,?

Kind of an ELI5, but I tune a radion into a specific frequency to listen to a station. If that frequency is constantly being modulated (changed), how is the radio not going in and out of tune? I expect it is finding a way to measure multiple frequencies around the tuned station and decodes the data from it's deviation from the tuned frequency?

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Ask Electronics TelepathicWalrus 3 months ago 100%
Good right angled board to board connectors

Hello, I am looking for a good way to mount a daughter board to a motherboard that can be ~~hot~~ swappable. I would like it to be able to mount securely preferably with mechanical clips or fixings. There will be up to 10A to go through it for power as well as around 10 signal pins. Obviously I can use several pins to get the required current rating. I have seen DIN 41612 connectors but I am concerned about the daughter board coming loose. If anyone can help me it would be much appreciated 😊

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Ask Electronics montar 3 months ago 84%
What devices should i look for to get a -30V power supply.

I've got a VFD display on board along with UPD16311 driver is made for negative voltage around -30V and i think so is display (i couldn't find any info on display) and I'm doing it mostly from junk parts. I want to know what devices could/should contain power supply for such voltage. I've tried -12V from psu i've got lying around but it didn't work. There's also a chance that display itself is damaged but there's no visual sign of it.

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Ask Electronics Rolive 3 months ago 100%
A4988 driver module sleep pin

According to the A4998 datasheet you're supposed to wait 1 millisecond after waking from sleep to allow the circuit to energise. What is the worst that can happen if you neglect to do this? I use stepper motors to drive a plant watering pump and losing a step or two really isn't an issue. Is there a risk of damaging the module or is losing the first step the biggest risk? I trigger the pump by pulling the EN pin low and a 555 timer on the STEP pin makes it pump continuously. It seems sensible to pull the SLP pin down as well with it as that saves a little bit of power.

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Ask Electronics batvin123 3 months ago 96%
will i damage my car electrical system with a 24v solar panel

I have a 3d printer in my car powered by a bluetti eb3a. The bluetti is charged by the 12v outlet in my car while driving. I have a 24v solar panel i want to mount to the roof of the car. My bluetti has only one dc 7909 input. So got a a Y splitter to combine power from the car and panel. But when plug it into the car outlet that turns off when i turn off the car, the solar panel turns on the stereo. Thats not the case with the outlets that are always on. I am worried that i will danage the car electrical system from a 24v solar panel flowing electricity back into the car?

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Ask Electronics AbidingOhmsLaw 3 months ago 100%
Teensy 4.1 tiny power IC replacement, Tips needed

I have a project that is using a Teensy 4.1, the cheep 5v regulator I was using in the project let the magic smoke out for no good reason. I replaced that but now the Teensy boots and runs for about a min then quits. There is a TLV75733P power IC that is supplying the 3v3 and it gets hot then quits supplying power. Since that IC is $0.46 vs a new Teensy 4.1 ~ $40 I want to try and replace it. I have done a bit of SMD work but not tried to remove a tiny chip with a GND pad before so I’m looking for any tips. The PCB of the Teensy has header pins so I can’t really get good contact to a hot plate to preheat the board. ![](https://lemmy.ml/pictrs/image/d61adf2d-dc83-4eff-bdfa-75eac4be5e09.jpeg) ![](https://lemmy.ml/pictrs/image/cf1f1607-ba07-4255-a430-f9c90ef96b11.jpeg) ![](https://lemmy.ml/pictrs/image/d97a2533-4aa7-4452-8127-cf6cf9766112.jpeg) ![](https://lemmy.ml/pictrs/image/66590873-7355-420d-9a1d-2aa945c45b2a.jpeg)

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Ask Electronics batvin123 3 months ago 96%
DIY electronics and Insurance

I am working on a WLED project, using a esp32 in a 3d printed enclosere. But my dad says that i can't install it because it is not UL listed. He is worried if the house burns down, the insurance company won't insure it due to diy electronics possibly starting a fire. What am i to do, i am not developing a project to sell?

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Ask Electronics Burn1ngBull3t 3 months ago 100%
Need help to build a ChooChoo bike whistle

Hello ! I recently 3dprinted a train whistle that usually works with a mouthpiece. It works by simply blowing air in it. However, I would like to convert it to a whistle for my bike. For that I would need a system that could blow air in it, instead of myself, with the press of a button. Any idea on what i could start with to build that ? It would be best if the circuitry was quite compact too. Thanks !

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Ask Electronics RandomUser 3 months ago 100%
Long term storage of LiPo device

I want to store a battery powered device long term (decades) as a reference article, it will never be switched on or charged again. The problem is that it contains a small LiPo battery that will be very hard to remove. Is there likely to be any significant risk I need to worry about? Once depleted will the battery be relatively inert?

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Ask Electronics hylobates 4 months ago 100%
[Somewhat solved] NES outputs 4.6V on controller port instead of 5V which prevents Blueretro from functioning properly

EDIT: Thanks everyone for you help, that has been very instructive. I think I just have a very poor quality cable adapter. Given that Blueretro is mostly an opensource DIY project, I’ll make a cable adapter myself instead of trying to fix what would obviously not function properly. Hi everyone, First of all let me say that I’m a total noob in electronics (I really only know the basics) and I’m facing an issue that I really don’t know how to tackle. I have bought a Blueretro NES adapter on Aliexpress ([this one](https://fr.aliexpress.com/item/1005004662621894.html?gatewayAdapt=glo2fra4itemAdapt)) and it does behave erratically when powered by the console alone (Bluetooth not working, LED indicator down, random outputs to the console). When I’m powering via USB, everything function properly. So I guessed that I might have a voltage issue on the NES side. I tested mine and make a few friend test theirs (5 in total including mine) and the result is still the same: the controller ports outputs between 4.6 and 4.8V instead of 5V. The Blueretro itself apparently uses an AMS1117 ([picture here](https://i0.wp.com/www.blue-retro.com/wp-content/uploads/2022/07/retrocore.png)) which, from my understanding, is stepping down 5V to 3.3V (wild guess, I don’t really know what it does, just quickly read the datasheet). So, sorry for the long intro, here are my questions: * Is it wise to try to step up the voltage from the NES to the Blueretro from 4.6V to 5V? How would it be possible? Is it even possible? * Given that the Blueretro is taking 3.3V apparently, is it possible to step down from 4.6V to 3.3V instead? Is it wiser than stepping up? Thanks in advance and sorry for the long post :)

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Ask Electronics ch00f 4 months ago 91%
Any thoughts for custom-sizing a thin glass sheet to protect an LCD screen?

So my wife cracked the screen of her Playdate console. I got a replacement memory LCD (Sharp LS027B7DH01A), but the LCD is mounted with optically clear adhesive directly to a piece of glass which is adhered around the edges to the console’s faceplate. The glass measures 65.15x41.64mm by 0.65mm thick. Definitely not a standard size. I can’t find anywhere to buy glass so thin and so large. My first thought was to cut a phone screen protector down to size with a glass cutter. My first attempt failed because the screen protector I bought was actually coated in plastic on both sides. Even if I got a straight cut, I couldn’t find a way to slice through the plastic layers cleanly. Any ideas on where to find cuttable glass sheets this thin? I could try more screen protectors, but there’s no way to know if they’ll work before buying them.

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Ask Electronics glarf 4 months ago 100%
Has anyone tried this out? Turbocase Generates A PCB Shell For You hackaday.com

I came across this today and I thought it might be an incredibly powerful tool. So I was curious to see if anybody in this community has used it yet?

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Ask Electronics fenndev 4 months ago 100%
[Request] Components/Tools List for DIY, analog 'Beginner Electronics' Kit?

I'm new to electronics and looking to assemble an array of components and tools for working on and designing electronics & circuits. Something immediately apparent is that all of the widely available kits orient you towards working with microcontrollers and SBCs; these kits are cool, but I want to have a halfway decent understanding of the underlying analog components and circuit design before I go digital. With that in mind, what should I get? If anyone could specify specifics to look into, I'd really appreciate that! Thanks for the help. **Current list** * A decent breadboard * Jumper wires * Multimeter * Batteries * Variable Power Supply? * Assorted resistors (1Ω-?) * Capacitors (Electrolytic and ceramic?) * Various ICs? * Transistors? * Diodes, probably? * Potentiometers

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Ask Electronics Rolive 4 months ago 100%
PCB making with laser printer toner

Hi everyone I've been experimenting with methods of applying etch resist with a laser and dry film. The process is kind of arduous and error prone. Developing with sodium carbonate solution to clear unexposed etch resist takes long, doesn't work well and if you leave it too long the developed etch resist will break as well. I use a laser module attached to a 3D printer to draw the PCB (LCB?) on the etch resist. This laser almost instantly solidifies toner for laserprinters and also almost instantly hardens dry film. Using powdered toner and a laser would be a much quicker way to apply etch resist since the excess can be wiped off and reused easily. The problem is applying a uniform layer of toner. Suspending toner on the surface of water and hydrodipping the plate seems to work but drying takes too long. Spray coating could work but is messy. Isopropyl alcohol softens the toner too much making it impossible to clean the excess off. I have not tried using a roller or electrostatic application yet but that could work well. Does any of you have experience with this and have ideas/advice?

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Ask Electronics fnafdesktopfan111 4 months ago 94%
Can I fix a missing capacitor by just soldering the spot short?

So, I've got a laptop screen that's giving up on me. 2/3 of the screen runs alright but the 1/3 on the left edge is acting weird. Half of the broken section displays an image but the image smudged and weird, while the other half is just dead. I opened it up to see what's up and, lo and behold, a wee tiny capacitor is missing (I know it's a capacitor 'cause I looked of the board marking, C248). Now I'm wondering, since ordering a single capacitor just for fixing this screen is not worth the effort, can I just... put some solder in there to at least get power to where it needs to go? I know it's definitely not ideal but, this is an ancient laptop. Putting in the effort to fix it perfectly is not exactly a great value proposition. What I want to know most is, will the screen be damaged if I do this, or what could go wrong if I do this? I'm pretty new to DIY electronics fixing so sorry if this is a stupid question. Thanks in advance y'all. Cheers!

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Ask Electronics poopsmith 4 months ago 100%
Routing USB signals on 2 layer flex PCBs

Does anyone have any advice on routing some high speed signals on flex PCBs? I'm looking at jlcpcb because of the low cost but I'm having difficulty getting impedances to be decent. My requirements are: - 45 ohm single ended impedance (maybe? Def doable) - 90 ohm differential impedance (usb spec) - 5A current on power pins But if we look at the capabilities: https://jlcpcb.com/capabilities/flex-pcb-capabilities - 2 layer - substrate thickness (PI) = 25 um - 1 oz pour thickness = 35 um - min trace width/spacing = 4/4 mil = 0.101/0.101 mm - ε = 3.3 Is this feasible with this stackup? I'd like to do a 1 oz pour because of power traces, but there's also 0.5 oz (18um) and 0.33 oz (12um). For the differential signals, when I'm doing impedance calculations, I can get to roughly 70 ohms using W=100um, S=200um. I don't think this is good enough. I think I can get away using a 0.33 oz pour but then I'm worried about the power pins. And for the power traces, I'm needing 2.2mm, which is reasonable for the pins on a USB-C connector. But if I try using the 0.5 oz or 0.33 oz pour, it gets to be 4.2 mm and 6.3 mm, which seems impossible given the pins are tiny and very closely spaced together. Even with vias to the bottom layer, this seems problematic. Anyone have any advice here? This is just for a hobby project, so I'm really not looking to change fabs because of costs.

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Ask Electronics DNOS 4 months ago 100%
trying to fix a wifi antenna need some help 😅...

Hy I bought a cheap Yagi wifi antenna need some help cause the previous owner broke it and tried to fix it red neck style... It didn't work ... I hope I would be able to add a picture here is a breaf description anyway it's the cheapest brand you can find online the main element is formed into an oval shaped metal ring and here comes my question where should I solder the middle wire ? On one end ? On the other ? Should I pass it throu the (hollow) metal ring and weld it back to himself ? I have seen people build Yagies with similar ovaly shaped rings and they made the cable pass through half the ring and weld it there the problem is that my ring is shaped exactly like a C it doesn't have a second gap in the middle of the left part ... (Here=>C) English is not my first language hope it's good enough to be understood ask if not 👍🏻

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Ask Electronics alphacyberranger 4 months ago 95%
Does mini 12V DC diaphram water pumps like this get really hot after running for 5 min?

I'm trying to use it as a water pump for my aquarium. I'm using a 6V 4.5AH battery with a DC step up convertor to power the pump. After about 5 minutes it gets really hot. Is this expected?

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Ask Electronics Jimbabwe 5 months ago 96%
Building DIY a smart doorbell but would appreciate some help with the power and wiring

Hello, and thank you in advance. I'm making a privacy friendly "ring" cam/doorbell following this guide: https://tristam.ie/2023/758/ which has been great, but requires running a micro-usb cable down to the doorbell for power. I'm hoping to improve on this by using the existing doorbell power instead. The problem is that I'm a DIY electronics noob and I can't create a mental model for how it should all work. The picture I attached is my existing doorbell wiring scheme, which is as simple as it comes. I totally get how this works. Pressing the doorbell completes the circuit and makes the bingbongs. But this will have to change so the new door cam gets power full time. Ideally without the chime bingbonging full time. In addition to the ESP-32CAM, button, ring lights, etc., I also bought these: https://www.amazon.com/dp/B079FJSYGY which I thought might be needed to complete the circuit? I measured the voltage after the transformer and it was around 18 volts, but maybe this is AC and I want DC? Generally I don't know where in "the loop" to put things. Also, all the existing components are very far apart from each other, so I would love a solution that doesn't involve running any new wires through the walls. Any help is appreciated. Thank you!! xoJimbabwe

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Ask Electronics Grass 5 months ago 100%
Reverse emmc/microsd adapter

So I used something like these some years ago to recover data off a phone, but I was wondering if the reverse is possible in having a bga soldered adapter with a microsd slot on top. Or if PCBs can even be soldered together like that. I've never actually checked if bga chips have raised pads or something. The purpose would be for rapidly testing custom firmware for shitty old devices that were designed to be replaced without removing the emmc to flash it separately.

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Ask Electronics AnarchistArtificer 5 months ago 100%
What's this thing called?

This was a switch that got its wires pulled out. I learned how to desolder today in order to remove it from the little switch board and now there's three holes where this used to be. Does this component have a name, because I'm wondering whether I can just get a replacement one like this. There are lots of tools and supplies at the makerspace I used, but I need to know what I'd be looking for. Alternatively, what else might I be able to use to do this? I suppose I could just trim and strip the wires and shove those through and solder, but that seems...crude? I don't know. I'd prefer something with pins because I practiced soldering and desoldering using some broken electronics I had, and I'm more confident with pins than something so freeform. Thanks for your time.

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Ask Electronics nmill11b 5 months ago 95%
I'm looking for large, battery powered customizable Bluetooth buttons

I am looking for some sort of big programmable buttons. Not sure if something simple exists. Basically, this is to enhance flow through clinic, looking for a relatively simple solution. I just want some big battery-powered bluetooth buttons that I can give custom commands in tasker to text tell people to assist with tasks or bring me certain things. I'm not sure if something simple like this exists. (Thinking of like three or four different colored "easy" buttons). I haven't found anything quite as specific as this, but it's been something nerdy I've been thinking about that would save me time.

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Ask Electronics Rolive 5 months ago 100%
Designing an efficient LED array

LEDs will conduct more current when they get warmer and differences between individual LEDs mean you cannot easily put them in parallel. A constant current DC supply will be good enough for part of the LEDs but will overload some others. To normalize current a series resistor is used with each individual LED. Now, those resistors waste a bit of power. Are they really necessary? If you put several LEDs in series the individual differences become negligible at some point and a constant current supply will suffice for several strips of series LEDs in parallel. How many LEDs would this require? Another possibility would be to have the resistor in series with a strip of LEDs. I got some LED strips off AliExpress that run on 12V and each individual LED has a resistor in series with it. I believe this to be quite wasteful and it would be better to have several LEDs in series with a current regulator instead. The LEDs will end up in an autonomous greenhouse where power efficiency is important.

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Ask Electronics WhyAUsername_1 5 months ago 100%
Suggestion for mounting ServoMotor on the door for Automatic Door Unlock with ESPHome on ESP32

Hello Lemmings, Hope you guys are doing well. Objective: Open the door automatically through HomeAssistant My Plan: 1. Use an ESP32 and flash ESPhome. Wire up Servo Motor (SG90) with ESP32. Tie a thread on between the Servo Motor Arm and the physical latch (physical latch that I can pull to unlock the door) such that when the servo motor turns from -100 to +100, the latch is being pulled to cause the door to be unlocked. 2. I am planning to power this using AA Cells + DC DC Boost convertor. Issue: 1. How do I mount the Servo Motor on the door? 2. Is there any other (read better) way to achieve the same result? 3. Would you recommend any power source other than AA Cells? Image for reference: The latch has a keychain-like loop where the thread is tied. To unlock the door manually, I pull the latch towards right (---->) . This action is planned to be automated by Servo Motor. ![](https://lemmy.world/pictrs/image/ee5bec73-054c-4508-b8ea-fbe439d94a0c.png)

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Ask Electronics Rolive 6 months ago 100%
Making a PCB, using solder mask as etch resist.

This is an idea that entered my mind. The traditional way is applying some etch resist like toner or dry film, etching away the copper and then adding solder mask before populating the board with components. Can the solder mask be used as etch resist instead? It feels like skipping an unnecessary step in the process. Why isn´t this more common? This way you won´t need the step of removing etch resist only to replace it with a slightly different compound.

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Ask Electronics Mr_Mofu 6 months ago 100%
Whats the Best Breadboard Starter Kit for beginners?

Ever since I've gotten into Retro Computing, I've been confronted about things like soldering, Circuits and Electrics in general... and it has made me want to try experimenting with my own ideas! That does however mean that im still pretty inexperienced and thusly don't have anything to actually experiment with either. So what kind of Breadboard Kit will give me the best and most things to start getting into this Hobby?

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Ask Electronics Rolive 6 months ago 100%
PCB solder mask making using UV resin

It appears to me that UV resin, used for SLA printers should be quite convenient for making PCBs with a laser etcher. You can spread a thin layer of resin on the board and quickly expose it using a laser engraver. It should be most convenient for silkscreen layers that are otherwise difficult to apply. I think the common method of applying UV mask and spreading it using a piece of plastic sheet is messy and I can never guess how much resin to apply. It's always too much or too little and it's always unevenly spread. And then the UV light exposure is another guessing game. I have a 500mw 405nm laser module attached to my 3D printer and could easily 'print' some PCB layouts on a thin layer of SLA resin. Does anyone have experience with this?

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