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Bits and PCs - 2024.05.23

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This blog section contains miscellaneous stuff. Things like non-commercial projects which could be useful to others, source code, circuit diagrams, LTspice files, amusing stuff and nonsense. If I write it all down, then I won't forget it.

Questions and [polite] comments can be sent to info@muman.ch. Generous donations and lucrative business proposals are welcome. Invitations to wild parties too, naturally.

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Optically Isolated Ignition Coil Spark Generator (30kV)

If you have an old ignition coil lying around, it's very easy to make a 30kV continuous spark generator. Perfect for your Frankenstein laboratory in the basement.



The Mighty Ohm Geiger Counter Kit and other stories (updated 2024.05.23)

Everything you will ever need to know about Geiger counters, featuring the Mighty Ohm kit. Plus another Arduino-based Geiger counter design, with circuits and code.


Using Frequency Modulation to regulate a DC control voltage - FEZ Duino C#

A PWM-driven R/C circuit can be used to produce a feedback-controlled DC voltage (0..~2V), which can be connected (usually via an opamp for high to low impedance) to a controlled circuit. It was written in C# for the GHI Electronics FEZ Duino microcontroller. It's been very useful for projects like intelligent power supplies, motor speed control, and anything that needs an analog voltage to control it, when you don't have enough D/A outputs. Very similar code can be used to control MOSFET switching. It's also very easy to isolate via an optocoupler.


M5Stack 8ANGLE Potentiometer and LED module - Arduino C++

This module has 8 potentiometers, 9 multi-coloured LEDs and a toggle switch. It has an I2C 2-wire interface ("Grove" connector), and works with 3.3 or 5V controllers. It's been particularly useful for manually tuning PID loops, with course and fine controls.



LCD Character Display with I2C interface using PCF8574 - Arduino C++ and FEZ Duino C#

For LCD1602 and LCD2004 displays. These displays are very cheap, and very easy to use. The display usually runs on 5V (but now you can get 3.3V versions). If you add the I2C adapter, you can connect it to a 3.3V controller if you replace the 5V pull-ups, as described in the article.



Yet Another Universal Motor Speed Controller - Arduino Zero

Want to do something interesting with your old washing machine motor?
Circuit diagrams and C++ code for Arduino Zero, coming soon!



Infrared Remote Control receiver with repeat key handling - Arduino

IR remote control of your controller is very easy to implement with a cheap IR receiver module. Instead of just using a bare LED, use a module that contains the photodetector, preamplifier and filters in the same package, like the Vishay TSOP4838 which works on both 3.3V and 5V controllers. There is a very nice Arduino IRremote library which handles almost all remote controller types. But it doesn't handle "repeat keys" very well, or keys which should not repeat. Here you'll find some simple code to do this for you.


Incorrect pinouts for Chinese TL431 SMD Shunt Regulator chips. The Reference and Cathode pins are swapped!

I recently bought a box full of MeanWell 9V power supplies. When I drew the circuit, I couldn't understand how it was working...


A Computer-controlled Precision Coil Winding Machine for less than $150

A cheap CNC 3018 router provides almost all the components you need to build a computer-controlled coil winding machine...


Retro Stuff...

WinForms: How to center a MessageBox over its parent window C#

Windows Forms is old, but is still widely used. The MessageBox.Show() method puts the message box in the center of the screen instead of in front of its parent window. This is very annoying, especially on a large screen. Many people have struggled with this problem over the years. Here is a very simple solution.



<to be continued...>