Crystal variable oscillator (CB9506E)

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

Galvanometer amplifier (CB21651E)
Obtained from a 1967 documentation, this circuit uses transistors from the time. The galvanometer can be a...
Bidirectional DC Motor Control (CB19566E)
Motors up to 2 A can be controlled by this circuit, which requires a symmetrical source. Although...
Six Transistor Superheterodyne Receiver (CB964E)
This sensitive MW receiver was found in a publication of year 1958., The circuit uses germanium...