DIY Projects

DIY - Do It Yourself Projects


I never planned to publish any of this work, therefore I never produced much documentation, to begin with. Frankly speaking - since most of the projects were of the type "one-off", I seldom produced more than a hand-drawn and just barely readable schematic. Sometimes not even that...

I have tried my best to reconstruct and recover the missing information to such a level that it should be possible for an intermediate or experienced hobbyist to successfully complete the projects.

Please note that most of the circuits were designed before microprocessors became a cost-effective way of building gadgets. Independent of this, most of the circuits can still be valuable as construction projects. 

The projects presented here are just a small fraction of simpler and hobby-friendly electronic circuits I have designed & built since. The list might get updated occasionally.


Most of the projects do NOT include full instructions - nor printed circuit board designs. However, all designs are proven and actually built, so the schematics should be reliable. 

Some designs contain lethal voltages and/or power levels. I cannot be responsible for any injuries you cause to yourself or other persons not following my precautions and the warnings.

All circuits presented here are designed by me unless otherwise specified. I am not knowingly violating any copyrights or patents - nor deliberately offending other people by presenting pictures, schematics, ideas, and other material as my own. The information presented here may not be used commercially, published, copied, transferred, or distributed in any way, without written permission from me.

You are allowed to use the information presented here, as the basis for your private or non-commercial construction projects.

Electric Motor Speed Controller (ex. for toy cars)

Pulse-width controlled DC-motor power controller with a soft turn of and turn off. Good for any kind of medium power DC-motor that should be started and turned off gradually. Maximum speed can be set - as the direction of rotation. Uses just a few of "plain vanilla" components.

Neumann U47 tube microphone refurbish

This project gives you instructions and hints about constructing a fully working U47 tube microphone from old and/or refurbished parts. The instructions might be helpful also during the repair and restoration of these microphones.

Power supply for U-47 tube microphones (+105VDC)

A highly capable special-purpose power supply for up to 6 Neumann U47 microphones. The power supply is fully regulated, foldback current limited, and can withstand indefinite constant short circuits. Output noise and ripple are very low (<200uVpp), a requirement for hum-less operation. Performance is superior compared to the original power supplies.

Animated Fortune Wheel

An 8-sector electronic fortune wheel simulator with effect lights and sound. Great for pre-school children, schools and bazaars.

Home Intercom Using Existing Old Telephones and Wiring

This clever circuit adds to your old household wired POTS (Plain Old Telephone System) phones an intercom system - without disturbing the normal telephone operation. This design uses only 30 components - including the PSU!

Valentines' Day Animated LED-Heart

4-Band Parametric Audio Equalizer (tone control)

A professional quality 4-band (mono) line-level analog audio sweepable equalizer.

S-Video Chroma Processor

Realistic Traffic Light Simulator

An unorthodox and unique traffic light simulator using only op-amps and comparators! Simulates one car lane and one pedestrian light signal. Can run automatically or be controlled by a pedestrian push button. Controls either small 5mm LEDs or optionally higher power (low voltage) lamps.

60W Ultra-cheap & simple Audio Power Amplifier

The amplifier is very simple but gives a robust performance. The chosen components are a good compromise between performance and cost. The overall performance is actually very good. All used components are simple garden variety types, that can be probably found in your own component junkyard. The amp is designed for 8-ohm loads, in which it can feed 40W continuous power with a distortion level of 0.1% or less. Instructions are only in Finnish.

40W TMOS Audio Power Amplifier

This is a fully functional and well-behaving matchbox size power MOSFET amplifier. It is compact, cheap and efficient, and good-sounding. It also utilizes and introduces a unique "dual-bootstrap" technique, invented by the author in 1984. This simple idea guarantees that the output stage can saturate symmetrically close to both power supply rails. This utilizes all available power supply voltage to provide the highest possible output peak power.

Simple DICE circuits

Throw you dices electronically.

4-channel Effects Dimmer

Throw you dices electronically.

One Minute Timer

Under Construction