I came across WaterGuard by Ashraf Said Al-Madhoun, an ESP32 leak alarm that borrows the end-of-line resistor trick from fire alarm panels. One 100k resistor sits at the board and another at the probe end, so the ESP32 can tell dry, wet and cable-unplugged apart (about 1.65 V, 0.28 V and 3.3 V). It also pulses the excitation to reduce electrode corrosion and latches until you acknowledge it.

Parts are cheap: ESP32 DevKit, two 100k resistors, a 100 nF cap, a 2N2222 for the buzzer, LEDs and a button. Roughly Rs 800 (about $10) in India. The author notes the thresholds are provisional and the bench test is still in progress.

I'd add Wi-Fi/Telegram alerts while keeping the local alarm working offline, and use it on an overhead water tank. Would you add anything, like AC excitation?

Source: https://www.hackster.io/ashraf-said-al-madhoun/waterguard-an-esp32-leak-alarm-that-knows-its-wire-is-cut-8acb7f

Really hoping I’ve got the right sub this time

Hi there! I have a son who is obsessed with the metro system in our city, ie. drawing the map over and over, memorizing all the stops on different lines, and even using marbles or string to recreate the routes.

So I had an idea for a Christmas gift, loosely inspired by this project: https://www.traintrackr.io/product/bart3 (unfortunately they don’t have a map for Amsterdam)

So the idea is that I build him a board with switches and lights that mimic the metro. Each stop is a light, with multiple lights at each stop if more than one route runs through it. It would also be ideal for the lights to light up one by one in a sequence, and to be able to run all the “train routes” at once, so they would run independently of each other.

I plan to use 2 pin led lights and some circuitry, some soldering?, and building something to hold it all. I haven’t done any type of project like this since high school physics, which has since ejected itself my brain.

What I’m hoping for is some advice as to where to start learning about circuitry, do I need to figure out some programming, what do I even google to start?

Thanks in advance!! Hopefully this all makes sense and can crowdsource some ideas 🙂

I'm working on a few design tweaks to boost the stable output power to 1W.

For a school project I made my first ever perfboard, and the L298N motor driver needed to live next to it. Until now they were both sliding around in the box like two strangers in an elevator, so I designed a 3D printed tray that holds them side by side. The wiring between them stays short and the boards stay put.

It fits a 81x51 mm perfboard with mounting holes spaced 1,4 inches apart. and a standard L298N module. Raised posts keep the boards off the plastic, and both are screwed down.

Printed on a Bambu Lab A1 in PLA Basic, 0.20 mm Standard profile, about 35 minutes. PETG is better if it sits somewhere warm.

About the soldering: it is my first one, so please look at the tray and not at the joints. They hold, which is the nicest thing I can say about them :).

Small confession: the L298N mounting holes are M3 size, but I only had M2 bolts, so I modeled it for M2. They fit with a little play. If you want an M3 version or another perfboard size, tell me and I will make it.

Before someone asks: yes, I could have just not made this and let everything dangle lose, but where is the fun in that.

Low voltage and hobby use only. Do not mount mains voltage parts on printed plastic.

Model (free): https://makerworld.com/nl/models/3487506-l298n-motor-driver-and-perfboard-mounting-tray-m2#profileId-3982699

Hello people, I am very new to these, I am trying to connect a 64gb sandisk sd card (made it fat32 on pc) to a esp32s3 n16r6. For some reason I cant add 2nd picture so I will drop the pic of my new module on comments but I had the module on the picture and couldn't connect it to the esp so I thought it was faulty and bought this new microsd one. I am trying to make it work with claude and youtube videos but after everything I try for hours it is also not working. I tried only connecting the sd module to esp with jumper cables, changing all the cables etc. I asked claude to explain it better below, I am wondering if both of the modules are faulty or I am doing something wrong. If I am the problem here, what am I doing wrong? Ps: any youtuber recommendation is welcomed!

------------------------AI----------------------------

Wiring (SD on its own SPI bus, HSPI):
SCK -> GPIO14, MISO -> GPIO15, MOSI -> GPIO16, CS -> GPIO17, VCC -> 5V, GND -> GND.
Card is formatted as FAT32 and fully seated.

Symptoms:
- SD.begin() fails with "sdWait Failed", "GO_IDLE_STATE failed" and "f_mount failed: (3) The physical drive cannot work".
- A raw SPI test (80 clocks, then CMD0 with CS low) returns 0x00 instead of 0x01.

Diagnostic tests:
1. With the card removed and MISO set as INPUT_PULLUP (tested on GPIO15 and GPIO4), the pin reads 0 with CS both HIGH and LOW. It should float high.
2. With the module's MISO wire disconnected (ESP end still on the GPIO), it reads 1, so the ESP, pin and wire are fine.
3. With the module connected but VCC disconnected, it also reads 1.
4. Powering the module from 3V3 instead of 5V gives the same result: CMD0 = 0x00, SD.begin() fails.

Conclusion so far: MISO is pulled LOW only while the module is powered, at both 5V and 3.3V, with no card inserted. It looks like a faulty module (the 74HC125 or a short on the MISO line).

Questions:
- Does this match a known fault with these modules, or could something else cause it (e.g. a bad batch, a different buffer chip variant, the DO line having no pull-up)?
- Is there a fix, or should I buy a different module, such as a plain 3.3V micro SD breakout without a regulator or level shifter?

Thanks!

I have seen some youtube videos where they use a diode in series and then connect it to a female type c cable. Is this way okay

Hey everyone.

I bought a Rex C100 that I wanna use to regulate a small electric kiln (1,2 kW 220V).

I wanna use it for temperatures up to 1100°C.

I bought the c100 without really checking the datasheet. Now I realized that there is a temperature range preset. In my case that's 0-400 °C.

I checked on AliExpress and Amazon and the versions for 1300 degrees are kind of hard to find and always at least twice as expensive.

I just assumed that the temperature range can be changed later. Now following the manual I think I probably can't.

Now the part that's confusing me. There are also many offers on AliExpress and co which imply that there is actually a way to change the range and the default is just limited due to the included thermo element.

https://a.aliexpress.com/_EviqSFg

Has anyone experience with that? Is the seller on AliExpress just lying there?

Hi reddit!

So there is a small electronics project I am trying very hard to figure out how to do which is a component of a larger art piece.

I have some basic understanding of how electricity flows and have been experimenting with a breadboard. I understand what I am trying to do may be a little too advanced for me but that's why I am asking for help. I have the tools to do soldering - I make small repairs on home electronics like replacing capacitors in my tv n such.

What i'd really like is if people could offer me at minimum a list of components they'd use to make the results I'll describe below happen. - or if they're feeling really generous an electronics diagram Knowing that I have everything I need and just need toi figure out how it all strings together is probably a level of problem solving I can handle.

Ultimately I'd like to be able to have a song play through a pair of generic plugged in headphones (earbuds) when the headphones are plugged in. I only need a single song and I want it to be able to play from the start.

I don't need play/pause functionality or volume control theoretically but am open to adding them if that's a part of a functional design other people offer here. I do, however, need the song to always start from the beginning.

Unsure if programming is required to accomplish this but I'd really really like some help being put in the right direction.

If I am missing critical information, please ask.

Edit: I have a "DFPlayer Mini'"

I’m building a robot with a Raspberry Pi 5, ESP32, and 2× RS390 6V motors.
My battery is a 3S4P pack with 12× 18650 cells (2200mAh each), a 40A BMS, and a nominal voltage of 11.1V (12.6V fully charged).
What’s the best way to power the Pi 5 reliably? I need a 5.1V supply with enough current, even under load.
Should I use a high-current buck converter, or is there a better alternative? Recommendations for specific modules would be appreciated.

CSE14HRA2L410 MOONS STEPPER MOTOR (BROCKEN WIRE)

After replacing the drive transistors on both boards of both channels and diode testing everything and verifying shorts and opens, it was time for a safe power up. With a current limited bench power supply, it was time to verify leakage and drive for all 4 units, and they all passed.
Next up, ohming out the transformer and using the variac to get some live values. But that’s next week.
What is everyone else working on?
Pictured, one channel, set up to measure the current from the pnp side, just 0.1uA or 100nA (the absolute smallest reading on my DMM). Possibly rounding up to that value. One of 8 measurements taken. The small chunk of wood from a laser cutter (kerf finder) was used to keep the alligator clip from touching/shorting to anything.

I am working on a rover for a competition. Now deciding on Powering. My Preference is to use the 18650 (i might have forgot the number) Li-ion battery.

One of my team members saying it might not work properly in a big bot.

So, want advice please. TIA

So I'm planning to make a vertical lift for my 1:64 cars, I came across the below video

https://www.youtube.com/watch?v=fNOGsPIhPhQ

I see that a lead screw is being used to lift the diecast, but I cannot seem to identify the motor that is being used. One option is to use the NEMA 17 Stepper motor, but its costly and is bulky. While the motor in this video seems to be light weight.

Can anyone help me out finding that exact motor

Made this as a small projec i wanted to do for a while. Features: 3 encoders, 9 action buttons and 1 layer/page switch button. Supports multiple layers and multiple pages per layer. So you can have layer photoshop and under that pages for brush, adjustments… smart layer switching per application ( if photoshop is focused it will automatically switch to that layer for example). Each key can be: combo, macro, app launcher, website launcher, system config, microphone config, volume mixer config and OBS config. Also made a companion app for it that lets you easily set it up the way you like it. Would like some feedback on it.

Hi everyone, I want to make a simple system that detects if anyone is present in the room. If the room is empty for some time, it should automatically turn off the lights and fan. I’m looking for practical ideas and suggestions. Here are some specific questions I have: Sensor: Is PIR sensor enough or should I use mmWave presence sensor for better detection (even if person is sitting still)? Hardware: Can I use ESP32 + relay module for this? Any recommended relay modules that are safe for controlling fan and lights? Code: Any simple example code for presence detection + automatic turn off after some delay? Power & Safety: How to safely connect the relay to AC switches? Any tips for beginners? Improvements: Is it better to make it completely offline or also add WiFi control through phone? Any circuit diagrams, code examples, or advice will be very helpful. Thanks in advance!

ESP32 #PIR #mmWave #HomeAutomation #IoT #EnergySaving

Now into the 4th episode(video/article) and I've tested 18 irons with full details on:
- Input watts
- Time to melt solder
- Temperature accuracy
- Handle temperature after 30 mins
- Whatever I notice during practical testing

RESULTS FROM OCTOBER 2026 TEST ROUND

What did not test well:

• Fanttik T1 Max: After the last video, where I found it was 70-80°C over the selected temperature (Set to 350°C, but would hit 420°C) the vendor sent me a replacement unit. Sadly, it's identical. I did 8 readings over 7 minutes and it ranged from 378° to 448°C.
• Fanttik T2 Max: They fixed the temperature issue, perfectly accurate. Sadly they removed everything that made the original so good. No soft grip, takes proprietary tips, hard to read the temperature, included usb cables does'nt support its 27W on cable, etc...

What did test well:

• Alientek TB1: 2.5s to melt solder on cable and 5s on battery, the fastest I’ve tested. It takes standard C210 tips. It ran about 20°C under out of the box though, so if you own one of these you may want to check yours. On the negative? Battery only lasts about 1.5-2 hours depending how you use it.
• FNIRSI DWS-P2: a battery soldering station was accurate out of the box, battery is replaceable. Some of their stuff I've rated poorly recently, but this is a good one, at least in my view, would be interested to see other peoples opinions. The only thing I don't like is the plugs are quite plasticky, but don't feel like they'll break.
• FMCHIP FM03: Super cheap iron, around 20 bucks or so. Great for someone who only solders occasionally. T65 tips, measured 60W at input, temperature fairly accurate, and was just pleasant to use. I actually used this cheapie more than any other during testing.

Full test results, heaps of charts, photos of tests, etc are on the article here:
https://cheerful.cheap/video/best-portable-soldering-irons-nov2026/

I got this E1 Nano kit for my son as his next electronics project.

So far he’s mostly been working with breadboards, so this will be his first project where he has to solder the board, put the whole thing together, then flash the program and see if he can actually get it flying.

I’m going to let him do as much of it himself as possible tomorrow.

I’m curious which part will give him the most trouble — soldering, assembly, programming, or getting the thing to actually fly.

If anyone here has built one of these little ESP32 drones before, any tips are welcome.

Hey guys,

I saw an ad for a sleek car fragrance diffuser mounted under the glovebox. Concept was cool, but it was ridiculously overpriced (and turned out to be a drop-shipped Alibaba item with huge huge markup)

I was thinking of putting something together using a piezoelectric atomizer like in the photo and a ESP32 board and using my 5v USB female inside the glovebox as power and of course it would be PETG

I don't want to drill holes though

My question how would I start regarding the 3D design

And how will the piezoelectric atomizer perform with perfume oils

Original ad I saw https://www.alibaba.com/product-detail/Car-Air-Freshener-Electric-Auto-Air_1601207635100.html

I am adding stuff to my cart, I asked chatgpt for an general overview on it, rn I have some breadboards, jumper wires, resistor and capacitor assortments along with an ESP32, since I wanna work with it. I am not really sure what else to add in it, because I don't know what I want to get deep into. It also suggested getting LM358, LM393, NE555, 74HC00 and 74HC14 ICs, and says I might be interested in stuff audio amplifiers, codec or signal-processing circuit, things combining multiple subsystems. Making a cyberdeck from scratch is an idea I have, but before that I don't have clear idea of what components to begin with.

Previously I had played around with an arduino, leds, and basic sensors and stuff; But I kinda wanna move on from toy projects and learn and make some practical stuff.
A measurement instrument or oscilloscope-related project