Audio amplifier circuit diagrams, but also preamp, equalizer, mixer and other electrical circuit diagrams.
Controllers and timers
Timers, alarms, detectors and other sensor based circuit diagrams
For your car
In this circuit diagrams category you can find speed meter, courtesy light, siren horns, etc.
Light and LED
Very popular circuits! Running lights, stroboscope, light shows
Miscellaneous electronics circuits
Extend your PC using these circuits
You need a power supply for your laboratory? Here are some electric diagrams of several types of power supply: high power, stabile voltage, battery charger, variable voltage etc.
Am, fm transmitters, receivers, RF amplifiers, detectors, VHF, wireless microphones, spy bugs...
Telephone circuit diagrams, phone bugs, custom ring tone... Make your phone glows when someone calls you and similar.
Tools and measuring
Build your own electronics instrument for testing components and circuits, or temperature measuring device...