Reddit:Electronics

I made a binary seven-segment wristwatch. Each segment represents a binary multiplier: segment B is 1, C is 2, D is 4, and so on.

Project info

Yep, I’ve used 1970’s to 1980’s era parts from Japan and Taiwan only. The whole thing is built around a mitsubishi jungle IC. The controller is external though. I have no way of testing it because analog TV was shut down a long time ago here in Czech Republic. Just built it out of love and compassion for RF circuits.

Fun fact: I’ve spent 6 hours just soldering all the components into their respective holes. There isn’t a single hole unused on that perfboard.

Hey everyone! I’d like to share a fun and useful project I recently built: a PI-controlled soldering iron system based on a Hakko handle, designed specifically for heat insert pressing into 3D prints.

You can enjoy this project from a few different angles:

1. A DIY Tool That Actually Works I originally bought a so-called "digital soldering iron" to make a heat press, but it turned out to be fake—it just used open-loop power control with a 7-segment display. No temperature sensor, no feedback, no reliability. So I decided to build my own closed-loop system using proper RTD feedback, MOSFET switching, and a real PI controller running on an STM32. Now it gives stable heat control, perfect for insert work.
2. A Showcase for My Snapboard Platform This project is also a working demo of Snapboard, my modular prototyping platform for embedded hardware. It’s like a LEGO base for breakout boards—strong and swappable, yet reusable across multiple projects. The potentiometer, OLED display, and power modules all snap into place cleanly with perfboard support. It’s been rock solid for building functional prototypes.
3. A Control-Theory Driven Design Instead of trial-and-error tuning or just using bang-bang control like most DIY temp controllers, I took a full control engineering approach:

• Collected step response data
• Fitted it to a first-order model
• Designed the PI gains using pole placement, not guesswork
• Analyzed performance metrics like settling time, overshoot, etc.

You can get a ready-to-go PI controller without hand-tuning. I even wrote a short doc on the theory and design [Notion link here].

What You See:

• OLED display shows SP, PV, and OP
• Potentiometer sets the temperature
• Serial data logging for step response capture
• Clean 12 V/24 V DC input with a switching regulator
• RTD temperature sensing and MOSFET power control

Credit goes to @i509VCB on the KiCAD Discord

Images floating around. Heard this is unconfirmed.

Hello everyone
This is my first PCB design from scratch, made in KiCad 9.0
It will serve as a mainboard for my bluetooth remote controlled car
Based around an Arduino Nano, it handles

• Driving motors (with L293D IC)
• An ultrasonic sensor
• A servo
• Rear status LEDs such as REVerse, BRaKe, Left turn signal, Right turn signal (like seen on real cars)
• Blinking the LEDs (with a 555 IC in the monostable configuration and a 74HC00 AND gate IC)
• An HC-05
• Audio (a horn and an alarm (triggered by the ultrasonic sensor after a certain distance))

It is a 4-layered PCB with In1.Cu being a power plane for +5V, and B.Cu being a power plane for GND, F.Cu and In2.Cu being signal layers

Has 4 2.00mm corner mounting holes

Here are the KiCad project files in my GitHub repo' if anyone would like to take a closer look:

https://github.com/darsh-agrawal71/bt-rc-car-pcb-kicad-prj

Image #1: PCB screenshot (Red trace = F.Cu, Orange trace = In2.Cu)
Image #2: Schematic
Image #3: 3D View screenshot

I've always thought that electronics where expensive and hard but after investing some time learning the basics I made this lil 555 timer PCB and I know there are some things that could be better but I'm really proud of my work

Couple of years ago I designed the STM32 Nucleo F303 based control boxes, for students to learn C coding on.

Multiple of my designs replaced very old, outdated designs, originally made in 2001-2002.

I was looking for the ways to improve it, and also, my colleague is not that willing to learn of its assembly, so I looked how to simplify it and came up with custom shield PCB for Nucleo, routing around the pins I will need only.

Once fully assembled I think it will look better than current version.

Shipping in PCBs has become extremely ecpensive where I live unless you buy in bulk...tried my hand at etching PCBs to develop prototypes...nice to be able to do this...ofc not having multiple layers adds lots of limitations, but I can see myself testing out new chips or designing my owm modules in an afternoon...

I built a thing. See gallery*

3KW 15-170VDC Programmable H-bridge driver. With adjustable Duty, Frequency (250Hz - 160KHz), and deadtime.

ESP32 for the controller

SSD1306 I2C 128x64 OLED Display

74AHCT125 Logic level converter and output control

IR2110 x2 hi/lo gate drivers

IRFP260N MOSFETS x4

Artic Cooling AM3 cooler from the junk drawer

15-150VDC to 12V DC-DC converter module - for gate driver ICs and active cooling

7-40VDC to 5V DC-DC converter module - for esp32, display and logic converter

PWM thermo fan controller module

Lots of various TVS diodes, some ferrite beads, the usual caps and resistors, and a handful of tactile buttons.

As the controller is a ESP32, it can be re-flashed depending on what we are trying to blow up today.

Inverting (Arcs/induction heating/Switching transformers) - Flyback (More sparks) - Half-Bridge - Motor Controller (zoomzoom)

Obviously the first thing to try is big arcs with Aliexpresses finest £6 'wind yer own primary' HV transformer for about 35KV output from a 35V 10A draw. (If I tune it in just right I get u/130V peak to peak in the tank) https://www.youtube.com/shorts/37gKJzHNFdA

Next was an induction heater, worked well at 90KHz and a 5 turn coil and 4uF in the tank, drawing 15 or so amps at 30V will turn bolts into LEB's...

Didn't play much with the induction heater on the bench though, as the fields play havoc with anything in range. PC crashes, monitors glitch, and unconnected multimeters showing random voltages.

Building the hardware was simple enough: check datasheets and assemble. I didn't make a diagram as I had a fair idea of what I wanted in my head, so I then just let my hands finish the job.

The firmware is another matter. Having never played with any of these little controller chips before, or tackled any kind of coding bar a few websites, it. was. a. challenge.

I found that if I were patient, the freebie chatGPT gave me a hand with bits as long as I didn't ask too many questions in a short timespan (using that was another frustrating experience in itself ha).

I got there in the end though with...

* Complimentary PWM output (using a synced GPIO pin for resyncs across the legs, as for some reason the ESP32 will fall out of phase occasionally when adjusting the frequency)

* Full frequency control on the fly

* Duty control with min/max limiter

* Switching deadtime control (with frequency-related limiter)

* 2 stacks of resistor ladder buttons

Yet to do

Polish and combine firmwares and add a mode of operation menu (argh).

Add current sensing, so it can scan frequencies for the sweet spot of transferring energy. (some hardware tweaks and more arghhh)

Large capacitor bank sitting at the input (as my power supply is not enjoying the huge pulse currents much)

More TVS diodes when I can find some that don't come with 30 quids worth of 'handling fees'

T'was fun to make, a steep learning curve to program, and great entertainment when built.

Mates enjoyed the firework show with the big arcs, jacobs ladder, and the odd game of 'how short a rollie can I light off the arc' , while I enjoyed getting some rusty as shit bolts undone, and watching people with short rollies fall out of seats.

All in all, it cost me about £40 or thereabouts.

10/10 - would make again.

*Bonus photos include late night shed visitors

Honestly... What is wrong with people?!?

My first thought: oh well the pictures text is probably in german or something. But once you realize you can't unsee it.

I can understand opinion content being written with AI, gosh, I wouldn't even mind if co-workers sprinkled AI on their emails, but dude, safety stuff? My goodness...

https://pidora.ca/safe-gpio-power-methods-that-wont-fry-your-raspberry-pi/

Stepped on this lm324 and it burrowed into my foot. People complain about lego but try being impaled by a quad op amp....

Source: dieshot.com

Contributors: 万扯淡 / Kurnal / Tony - ASUS Marketing (CN)

Picture of the main logic board from a camera… Trying my hand at pcb pics.

I work for an electronics company who design their own boards. Yesterday I was fault finding a board that had the IS07810DWW ic fitted but the board wasn't working. After looking at the schematic and the technical datasheet i found that they had design the board to use IS07810DW and fitted the IS07810DWW. Unfortunately the pin layouts are completely different and the DW version is 6mm too thin to fit on the pad profile of the DWW. So yea. We have 250 of these on the shelf.

This shows you should always get your work peer reviewed before getting the boards made.

Someone at Eight Sleep left this fun easter egg, Coffee and Donuts. Pod 4 Hub refused to sense a filled water container. Apparently whole Donut board had no power due to a short on 12v rail....

Just finished one of the most basic radios ever, the first model ever designed, it is the ideal radio to makie if you wish to learn how it works and , I'll be posting on my youtube channel : https://www.youtube.com/@RodrigoML-pianoandscience in the next few days a video it's montage and it's history, check it out!!

If you want to try it out for yourself this is the link where I bought it : https://es.aliexpress.com/item/1005008736707297.html?ug_edm_item_id=1005008736707297&pdp_npi=4%40dis%21EUR%2112%2C72%E2%82%AC%2112%2C33%E2%82%AC%21%21%21%21%21%402151fbc817532000043861726d078e%21%21edm%21%21%21&edm_log_data=gmod-edm-item-list-three-columns.track-edm-item-list-three-columns-log-link&tracelog=rowan&rowan_id1=lg_pkg_merge_202505210211_1_es_ES_2025-07-22&rowan_msg_id=531clg_pkg_merge_anto_%24274ed0436a6a4e8799df8303c0cb17bd&ck=in_edm_other&mem_info=XDXAsYMFsu7olsulSoj%20%20w%3D%3D-100203-lg_pkg_merge_202505210211-8gLzMKSZTaIlmI%2FUTIJ295DJlZfU2hMTN2j%2FB61xeDI%3D&gatewayAdapt=glo2esp

The PIC16F13145 chip is at the center of this, its under a dollar in pretty much every big supplier.

For those who dont know, The pic is a little microcontroller, less powerfull than an arduino but what makes it capable of this is that it contains configurable logic blocks. Basically you can reprogram the logic inside of them kind of like in FPGAs. I find it kind of strange how the arduino chips are like 2-3x more expensive while being less capable.

This project uses a PIC16f13145 curiosity nano dev board which is a dev board for a configurable logic bloc chip.

using no external hardware it transits digital data that can then be picked up and decoded on another radio.

For more details visit my post !

The configurable logic uses logic to turn on and off a pin conected to wire which acts as an antenna forming a square wave which causes harmonics allowing us to transmit at 96mhz. This is our carrier. Then we use timers to decide when to turn on or off the the carrier. We use on off keying which means the carrier is either on or off and to increase resilience to timing problems we use manchester encoding. Manchester encoding works by using edges or transitions in aplitude levels to encode 1 and 0. In our case we use the following:

bit == 0: outputs 1 then 0 → High to Low → IEEE Manchester 0

bit == 1: outputs 0 then 1 → Low to High → IEEE Manchester 1 In a spectrogram it looks like this:

When translated to 1 and 0 to be decoded it looks like the second image

We use a sync sequence before each data byte. in this case being 0b11111111. This allows the decoder to understand the timing and synchronise the phase of the manchester encoding.

you can see this as the carrier being turned on and off in a repeated pattern before a different pattern in teh spectrogram from gqrx from an rtl sdr.

In this example its transmitting 8 bits per second but it could be much faster, this was done so you could see the encoding in the spectrogram.

You could get real fancy and use a real 100mhz fm antenna but for our case we just need a wire that will radiate the rf carrier. Ideally the wire would be 1/4th the wavelength of the carrier which at around 100mhz is around 75cm but thats relatively long and for short ranges we can afford to make our antenna much smaller even if it costs us signal strength. In my tests i used a 8cm 22awg wire another good thing is that having a short wire will help filter out out of band frequencies such as our original 32mhz signal that creates our 96 mhz harmonic. Though admitedly, at the power level we are transmitting it doesnt matter that much.

I used an rtl-sdr and I used a python script (main.py) to read samples at 512hz for 8bps and then convert them to digital 1s or 0s which are written to test.txt for me to open on pulseview using the import digital data or binary data option. I can then use the OOK and manchester decoding function that's integrated in pulseview. You could also do this using python directly but then its harder to visualise what's going on. In an earlier commit it did do that though.

• sync_sequence : defines the sync sequence default is 0b11111111
• start_tx : set to 1 to start tx
• sending_sync : set to 1 when you send sync (otherwise only the txbyte wil be sent upon setting start_tx to 1

If you want to change the bitrate you can do so by changing the high and low bytes of the timer defined as 100hz timer even though its only 16hz by default