Microphone preamp (CB22043E)

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

LED Driver Circuit (CB25415E)
The circuit shown in the figure consists of a system for driving white LEDs (WLEDs) at low...
Transistor Crystal Oscillator (CB5115E)
The resonant circuit depends on the crystal frequency that can go up to a few megahertz. The...
Battery Expander (CB12755E)
This interesting circuit allows to obtain symmetrical voltages from a simple battery. Among its...