Crystal variable oscillator (CB9506E)

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

Voltage Controlled Current Source (CB910E)
The output current for this source depends on the voltage applied to the input. The operational...
Motion Detector (CB6662E)
This Philips circuit of the 70's makes use of components of the time. The DZD40 is an uncommon...
1 to 50 kHz sinusoidal oscillator (CB9511E)
The unijunction transistor for this circuit, found in a 1976 publication, may be 2N2646. The...