We found this circuit in an article in Radio Electronics magazine from November 1971. The circuit has several sensor inputs and is based on programmable unijunction transistors or PUTs.
This simple version of a function generator with the XR2206 was found in the May 1977 issue of...
In a modern version this circuit can use an LED in series with a resistor in place of the lamp. The...
This VFO was found in a 1980s documentation. The central frequency is given by the crystal and the...