Circuits by Tomi

Debugging RS-232 with logic analyzer

RS-232 serial interface is still quite widely used in many applications. Usually RS-232 Mini Tester with LEDs for indicating state of different signals is all that is needed to make things work. But sometimes seeing signals with your eyes is not enough for troubleshooting and testing. There are nowadays cheap logic analyzers (like Saleae Logic

Old "Atari" joystick to USB

The most common joystick type in home computers in 1980′s and some time after that have been Atari-style digital joysticks. Atari 2600 joystick pinout”>Those joysticks are named after Atari, because this joystick type was first introduced in Atari 2600 videogame and then adopted to the home computers introduced on ever since (VIC 20, Commodore 64,

Replacing flashlight bulbs with LEDs

One day I had an old flashlight that had burned light bulb on it. It was a small cheap model powered with two AA batteries. I could fix it with new light bulb, but going through the trouble of trying to find exactly suitable replacement light bulb felt like more than the value of the

TDR kit built

My Time Domain Reflectometer (TDR) circuit has been available as kit made by Far Circuits. The kit consists only of circuit board and components needed to build the circuit in a small plastic bag (you need to download the building instructions). The original circuit design is from my web page and Far Circuits added 5V

TDR circuit modification idea

You might know my Time Domain Reflectometer (TDR) signal source circuit published on ePanorama.net many years ago. It has worked well for me many times. Some years ago I made a modification to my own TDR unit. This simple modification allows me to use the same box also as a signal source with a wide