Circuits by Tomi

My LPT DAC story

Hackaday featured today LPT DAC circuit. Back in the olden days, around 25 years ago, sound cards were rare on PCs. One hack those days was the original Covox Speech Thing, that connected a simple DAC to to PC parallel port. The Covox Speech Thing (also known as Covox plug) was an external audio device

Conductive paint pen challenge

Farnell/Newark/Element14 has been running a Conductive Ink Challenge with deadline of 31st August 2014. In it the competition the plan is to draw artistic circuits by hand using nickel or silver-laced “ink”. The aim is to make eye-catching piece of art.  Judging is based on creativity, originality and technical and is final To test conductive

Video over UTP

Traditionally analogue video transmission is done using 75 ohm coaxial cables. Those video signals are not directly compatible with nowadays more widely used twisted pair wiring (CAT5, CAT6 etc..), which means you just can’t wire the signals directly form video output to a twisted pair wire. The mains problems in connecting 75 ohms video source

Arduino and ultrasound distance sensor

I bought some time ago HC-SR04 Ultrasonic Sensor Distance Measuring Module to play with ultrasound distance measurements with Arduino Duemilanove 2009 Atmega 328P SCM Board. The working principle of the HC-SR04 Ultrasonic Sensor Distance Measuring Module when the module get trigger “start” pulse, it sends eight 40khz square wave pulses and automatically detect whether receive

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,