Activation shield (CB6947E)

Found in an 80's Elektor, this circuit can control loads up to 750 mA with the BD139 and 100 mA with the used transistor.

Wien Bridge Oscillator (CB16226E)
The main feature of this circuit is that it provides a sine waveform signal. In this circuit, the...
Voltage Controlled Resistor (CB25150E)
This circuit behaves as a voltage controlled resistor and can serve as a small load. The circuit is...
Bench Audio Amplifier (CB18061E)
The circuit presented, from a 2005 documentation, can provide from 1 W to 2.5 W of output when...