Crystal variable oscillator (CB9506E)

Found in Radio Electronics from the 90s, this circuit can vary the frequency in small values around the crystal frequency.

Push Pull Output Amplifier (CB950E)
This old configuration of an audio amplifier has a push-pull two-transistor output stage. Output...
Astable Multivibrator (MSB016E)
This is the traditional configuration of na Astable Multivibrator using two NPN ttransistor....
Economic Ammeter (CB16606E)
This circuit is from 1987 documentation. The operating system used is not common today, but two...