Ask Electronics

Hi all, I have a water pump connected to an adapter (pictured) but I am having trouble getting it to run using any of the cords I had on hand; it calls for using DC-only & 12V (between 9-14). I have tried Googling around & browsing Amazon but I'm a bit overwhelmed with options. Can anyone suggest an adapter that'll get this little guy pumping? Please forgive my naivety & TIA.

Also, I hope that it's kosher I ask here. If it's not, please let me know if there's a better place. Thanks again.

I am powering a 5V microcontroller (arduino clone, atmega328p) using a 9V block and a buck converter. Now I want to let the microcontroller occasionally measure the battery voltage, so I can get an idea of how full it is.

My first idea was to use a simple voltage divider:

I've chosen the resistor values so that:

• the voltage at the measure output is < 1.1V, to be able to use the 1.1V internal reference of the atmega's ADC
• R1 || R2 < 10kΩ, since the atmega datasheet says "The ADC is optimized for analog signals with an output impedance of approximately 10 kΩ or less"

This is great and all, but what bothers me is that this circuit will constantly draw ~100µA from the battery.

So, my next thought was to add a mosfet to the divider, to switch it on only while measuring:

This is obviously bad, because now when the mosfet is off, the ADC input sees the whole battery voltage.

To address that issue, I've added a second mosfet into the measure path:

This works, and it does not draw any current, except while measuring.

However, it's quite a few parts. So I'm curious if anyone has an idea how to do this with just a single mosfet. It seems to me like it should be possible, but I haven't figured out how.

Oh, and if I'm doing something stupid here, please tell me :)

Is there a way to figure out my LED board and fix it myself? I got this LED light which works perfectly but the issue is the usb charger port on the left is not working for whatever reason. There are two ports one micro for charging the led and one usb for outlet charging. Is there a way to switch the charging to the usb port? If you guys have any resources for learning I would appreciate it too, I will get my feet wet and hopefully figure it out myself…

I am making a graphics card on the tang nano 20k board. I tried synthesising the design in the official IDE and it output:

[95%] Generate netlist file "/home/original2/Downloads/Gowin_V1.9.8.09_Education_linux/IDE/bin/VGA_out/impl/gwsynthesis/VGA_out.vg" completed

with no further updates for 40 minutes so far. I am on a 16 core system with 24GB of ram (the process is maxing out 1 core right now as well as using 6GB RAM). Why is it not progressing..

I do have a 60 by 80 array with 11 bit numbers in it if that is relevant

Hello! What would be a good way to learn about electronics in terms of creating them? I'm particularly interested in building my own keyboards and other PC peripherals, but I'm not sure what tools I would need, or what's a good knowledge base if I run into any issues. Any tips and or suggestions?

Thanks for all your votes and comments. From the icons that were submitted as requested, the results were as follows:

• Icon 1: 7
• Icon 2: 78
• Icon 3: 27
• Icon 4: 6

Icon 2, by @Double_A has duly been adopted.

In a transformer, why are both coils apart from each other? Wouldn't make more sense to have the ferrite core (tube shape), wind the primary coil around that and then wind the secondary coil on top of the primary? So that the magnetic fields are as close to each other as possible?

Serious question from a beginner in electronics. For reasons I do not fully understand, I have become fixated on the idea of collecting small amounts of electricity from “interesting” sources. I don’t mean “free energy”, instead, I mean things like extracting a few mV from being so close to a AM radio tower using two tuned loop antennas in phase with each other, or getting a few mV from the rain’s kinetic energy with PTFE and using two electrodes which are shorted when a drop of rain hits it. In short, I’ve done small experiments to confirm that I can get a few mV and enough to get me excited but not much more. I know I’m not going to get much power out of this, but I’ve been able to charge a NiMH battery a few mV by being a quarter mile from an AM radio station with my antenna setup. It would be fascinating to me if I could store these small charges in something like a 5V USB power brick eventually.

The smarter idea would be for me to harvest energy with the sun or from the wind or a stream. I’m tinkering with this as well, but larger amounts of electricity scare me for right now. I guess I’ve seen enough experimental sources of harvesting electricity and I’ve gotten the itch to invent, which is a dangerous itch for a newbie like me to have.

The best advice I’ve seen online (ok, it was ChatGPT) is that it’s just not worth it to work with such small amounts of electricity, because the equipment required is too expensive and sophisticated (e.g, devices to read the charge of a capacitor without discharging it) to make anything that’s efficient enough to be worthwhile. Would you agree? Do you know of some other fascinating source of gathering electricity that I should also waste lots of time on?

I just have all these electronic components and magnets and when I move them together the numbers on multimeter get bigger. it’s neat.

My wife gifted me this super cute mini miffy diorama from a gachapon. It uses two 1,5V cells and has a tiny led in it. I would really love to to add a 24h timer. ( it should stay on for 4 hours after turning it on then go to "standby" for 20h before turning back on) Do you guys think an attiny85 is the right thing for the job? Sorry of the question is dumb in any way. I am absolutely not an electronics guy.

Hi,

I'm looking for some help in a field that is super technical and I don't fully understand.

I'm planning on using a bunch of these seeed studio Esp modules for some home automation projects, especially because they have a lipo battery charger making it great for portable stuff.

The thing is the the ESP32s have U.FL SMD antenna connectors. Most of the antennas that you can buy with U.FL connections while are reasonably small, come with 50-150mm leads, which sort of makes the small size of the module a little less valid.

What I'd like to do is get a female U.FL SMD connector and make a small daugherboard with an 2.4GHz SMD antenna on it, for instance a Janson 2450AT42B100 or a Molex 479480001.

They go over the circuit board requirements quite thoroughly so I don't think designing it will be too difficult, but what I don't know is, they say that you need impedance matching on the circuit, and I see that there appears to be something that looks like it on the ESP circuit diagram, but I'm not actually sure if it is or not:

You can see it in the middle near the bottom of the diagram here: Seeeduino-XIAO-ESP32C3-SCH

So my questions are:

1: Is this a dumb idea, having a direct plug-on SMD antenna?

2: Is that an impedance matchning circuit between LNA_IN on the ESP chip and U.FL-R-SMT-1?

3: If I can't get a female U.FL SMD connector, would using one with a lead and shortening it to make the daughterboard able to be much closer to the connector affect anything? Do I need to ensure that the lead length matches the wavelength at all?

Edit: Found this SMD female U.FL, so they do exist.

I got my hands on an old e-ink price tag and want to repurpose this display.

Unfortunately, I can't really figure out, what this type of connector/bus is called. To me it looks like a standard issue ribbon cable.

There are some "universal" e-paper drivers (for example this one: https://www.ebay.de/itm/353141399922), but I have absolutely no idea, how to find out, if that's the right connector.

The device is made by Imagotag, if that helps.

Edit: I added a picture of the panel: https://feddit.de/pictrs/image/42ee4f60-231a-4c42-9a66-6c369134c49c.jpeg

None of the "markings" returned any results and the QR code couldn't be decoded by my phone.

Hi, I am automating my manual switches at home with ESPHome on NodeMCU. For controlling the switches, I am using 8 channel relay module.

The back of the board has solder-points sticking out. I will be installing this relay module inside the switchboard. So I want to put it in some kind of enclosure.

Just wanted to know your thoughts on enclosure. Should I just wrap the whole thing in electrical tape? Or a plastic box maybe?

Hi everyone! Recently I have gotten interested in communication protocols and have been looking for one (with little success, hence my question) which would satisfy the following requirements (in prioritized order):

• All devices should be able to initiate communication (not your typical master slave with polling)

• Devices should be able to address messages directly to one another without a single one permanently taking on some host/master/relay role

• Devices should be hot-pluggable (A new device may be connected to the network or removed from it without problems even when the network is up and running)

• The protocol should be stable and immune enough to noise so that it can be sent through wires up to at least 5 meters, ideally even up to 10-50 meters.

• It should be simple, implementable even on low-perfomance microcontrollers.

• It should have its maximum transfer rate in the kilobytes per second range or preferably even megabytes per second.

I have looked at I2C, which for the most part would be fine, but as far as I understand it was not meant to be sent through a wire and it would be quite vulnerable to interference. (It also is by default a master-slave protocol, but it also has a multi-master mode, so maybe making every device a slave and a multi-master master at the same time could work?)

The rest of the protocols I looked at were all master-slave, which, for my purpose, is unacceptable.

That being said, I would be grateful if you could give me some pointers as to what protocol may satisfy these requirements and perhaps even on what sort of wires and signals it would require (twisted pairs? Differential signal? Shielded twisted pairs? Could plain simple wire suffice? etc.)

I just came across this and thought I'd share. I've struggled to get headers and IC's off boards after soldering them on backwards/upside down. This video shows a cool trick with a piece of copper wire that makes them very easy and quick to get off without expensive tooling. I was thoroughly impressed. Hope someone else finds this useful too.

I purchased an e-bike which was advertised as just needing the batteries replaced. The li-ion batteries had been sitting dead for months. Once I got the battery removed it was clear that was not the case. You can see the hole where the plastic melted from this component overheating on the board. The burnt one is the same as those in the center of this photo.

What is it and how do I determine the correct replacement?

Trying to identify a component on a pool control board.

It's related to the T-Cell functionality of the board, since everything else like sensing, timing, and whatever else works on the board.

Component got water on it, most likely when a not uncommon occurrence of water jetting out from the filter and splashing onto the board eventually got where it shouldn't.

@askelectronics

Hey everyone,

I'm a complete beginner in the world of soldering, and I'm facing some frustrating issues with my soldering iron tips. After just a few minutes of use, my soldering iron tips can't melt the solder anymore.

I always keep a sponge nearby and make sure to clean the tip frequently, just like I saw in tutorials. However, the tips still look a little "burned"/ black. Am I doing something wrong? Or could it be related to the soldering equipment I'm using? I bought a $20 kit on Amazon just to practice.

I'm trying to use an LIS2MDL ic with an Arduino nano on a custom PCB designed in KiCad. I tried the Arduino example compass script for the ic and it didn't work. It just prints "Magnetometer Test" and nothing else happens

//Edit: It's a SAS drive. thanks for the help :))

I bought two of these a long time ago, and I recently tried to connect them to a SATA III connector without luck. The size seems to match up, but the block between the two pin segments seems to block it from connecting with SATA III.

Can you help me figure out what kind of adaptor I need ? :))

Hello, I have a circuit that will need to return connected hardware to a default state if power is lost. The hardware can handle continuous voltage, so I'm thinking a simple solution would be to use a battery to provide that fallback power source. To avoid draining the battery, I'd like to connect it through a relay on the normally open contact and energize the relay directly from the main power supply on my board.

Do I need to look for anything in particular to make sure the coil on the relay I choose can sustain constant voltage for potentially months at a time without damage? Or, is there another similarly low cost and simple solution you'd recommend?

The circuit runs on 12VDC from a [Mean Well IRM-10-12 (specification), and the relays I have on hand are OMRON G5LE-14-CF 12VDC (specification). I don't see anything on the relay documentation that specifies a maximum duty cycle.

I'm curious and am playing around with a new EDA tool and am looking at practicing by designing a PCB which should be roughly 28x26mm footprint (give or take a few mm...).

It should be an LTE cat 4 device, connected by USB type C for the framework laptop and is unlikely to include antennas.

Where I struggle is identifying potential modems to use. The only one even remotely close is the u-blox LARA-L6, which is 24x26mm. What alternatives are there?

I am trying to see what gets sold in these USB dongles but there is little info. The few I have identified seem to make use of the Qualcomm 9207, but its's unclear to me if its a ready chip (which is what the MDM9207 is?) Or if it is an IP core to integrate in one's own chip?

A video I came across seem to indicate it (the MDM version) is tiny:

https://www.youtube.com/watch?v=ToCyUCIoXEM at 2:13

But will probably needadditional things to be integrated and I created an account at Qualcomm but they won't give anything unless I'm certified from a company to be a customer and actually integrate it...

I have a whole bunch of them. They are possibly a bit older (70s, 80s) judging by other contents of the junk box they are from.

There are no labels of any kind, but on the top they have stripes that look hand painted.

For at least some of them the resistance roughly corresponds to the color code.

So, I'm just curious why I can't find anything about these on the internet.

As the title says, I'm looking for a Linux/macOS-compatible EPROM programmer. I'd like to be able to program parallel (E)EPROMs in the 27xxx range. The newer XGecu programmers seem to not be compatible with Linux/macOS, and the selection of TL866(II) clones is too overwhelming for me to be able to choose one.

Any suggestions?

This photo shows the power conversion side of two versions of the same board. Input is up to 60V DC, board converts to 5V and then down to 3.3V.

The top board works correctly all the time. But the bottom board has strange issues. Everything works perfectly when I connect it to my bench power supply at 53V. The board powers up with no problems. When I connect it to the daisy chain of other boards, it suddenly will no longer power on, despite ~54V being passed through correctly to downstream boards.

This is a real head-scratcher for me, and I'm having trouble making sense of it. I'm not so much looking for The Solution as to what steps I should take to troubleshoot this. There were some issues attaching the image, so in case it doesn't show up.

https://photos.app.goo.gl/MCx7Q4BDbKTv68EJ8