Reddit:Electronics

Microscopic image with $11 usb microscope

Nabbed a huge lot of parts at an estate auction. some fun transformers in there. gonna use some for my ghostbusters cosplay build.

Still got lots of tubes to sort out

Found this interesting bit of kit at a thrift store. It's an 80s electronic bathroom scale. Measures weight by moving a piece of steel, wrapped in aluminum through a big inductor. Like a reverse solenoid. That then goes into a board with a TL081 and a CD4050 to generate an 11.68KHz square wave at rest (display reading 0.0lb/KG.

When weight is put on the scale (or i move the metal under in the solenoid) the frequency of the square wave drops, and the display counts up. To a max of 136KG/300lb.

This is confirmed by connecting my function generator to the white (signal wire) going to the 3 oin DIN and watching the display increase as I turn down the frequency.

Tinkering around with an N555 and a handful of 4017 ic.s. simple Led chaser idea.

N555 triggers the 1st 4017. This one controls 2 4017s wich at there turn controls the 10 4017s powering 10 leds each. Creating a chaser effect. Eventually the outputs wil control up to 10 leds per output.

Still far from completed. Stil need to figure out how to get the rainbow leds to change colors. As the 4017 is on/of. And the leds are operating between 3 and 3.2volts for changing.

What started ad a simple old-school project is now starting to get complicated 🤔

I took apart quite a few microwaves over a year or so and i never saw a plastic HV fuse in them yet so i thought it would be good to share.

These HV fuses are esentially built using the same principles of operation: during overcurrent the thin thin wire melts and the spring retracts completely (like, totaly completely back) as soon as that wire melts enough. That quick spring retraction helps to quench the arc as fast as possible.

Rated for fast blow 700 mA at 5 kV if you cant read it.

Ripped of the trace when pulling out the transistor that was in there so had to get cteative using solder as the new trace.... ugly but it will do the work.

I’ve been working on a modular IoT platform called Genesis, and wanted to share a fun offshoot of it — a single-port, battery-powered version I’m calling the “Pillar.”

The port on top accepts various plug-in modules, since they all follow a mostly consistent pinout. The interface includes:

• 2x GPIO
• 1x ADC
• I2C, UART, and SPI

It’s just one port, so it’s more of a fun side experiment — but it still supports a decent range of modules. Could be handy for throwing on a relay, sensor, or even a tiny display for field testing. Runs on a Li-Ion battery and has built-in charging via USB-C.

Blue LED for ‘good’ (<600ppm), green LED for ‘average’ (<1000ppm) and red LED for ‘poor’ (>1000ppm).
The board will also print the CO2 values, as they change, on the RTTViewer.

This was a project that I worked on a couple months ago that was really fun and cool, I followed it on YouTube if you look up adhd engineer. (Black was the first version)

Made a full adder with CSD15380F3 N channel FETs and 0402 resistors. I probably won't actually get it made.

For my home theater controller i use an existing obsolete hmb2260 settop box and keep the 4digit display as its integrated in the casing. so an arduino nano can display info on it. The ltc display is common anode and its multiplexed. I used an mcp23017, register b outputs are connected to each segment (7seg +dp), via uln2803 darlington transistor ic. The anode of each digit is switched by a 2n3904 as this transistor can switch the required current (8x25ma=200mA max). This transistor is switched via 1k resistor by register A of the mcp. So via i2c, only 1 digit is powered at the time resulting in the current flow from 5v supply, via 2n3904, via led segment(s), via 180 ohm resistor, via uln2803 darlington, to ground. I could by software in the arduino switch each digit in a row every 20ms without seeing a flicker. So it works quite well.

Here's something I hooked up at the weekend - it's a prototype for an NFC card reader door entry system, with buzzer and doorbell I/O + lock strike plate activator. The ESP32 is running Tasmota and the board speaks to Node-RED via MQTT over wifi.

Astable multivibrator LED ckt