Microphone preamp (CB22043E)

This preamp was found in an old English publication. Any usage JFET can be employed. The output is high impedance.

Sensor with photo IC (CB24137E)
Based on an integrated circuit CA31062 which consists of a photosensor, this circuit was obtained from...
Sound Intensity Meter (CB11533E)
This ultra-simple meter uses an output transformer and a small speaker as a microphone. The...
Oscillator up to 50 MHz (CB23739E)
The frequency of this oscillator depends on the crystal used and the transistors. The circuit was...