Circuits by Tomi

Diode detector for RF

Here is a simple diode detector for RF signals. I can feed RF signal from left and get DC output from right. The DC output can be fed to Arduino analog in. The diode in the circuit is germanium diode for low voltage drop. The circuit works well for fractions of volts to several volts

AD9850 based signal generator

Few days ago I tested AD9850 DDS module in home in hope to some day have a working signal generator using it. The initial tests went well, so I could plan the next step. I was already doing some information searching to make decision if I should do the controlling using web interface (with Ethernet

My PC speaker PWM story

Here is another story from the same era (early 1990′s). It is a continuation to my LPT DAC story. Before PC sound cards became popular, around same time as LPT DAC circuits became popular, PC speaker was also used to play back digital audio. Software (game and other) wanted to have the option to use

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