This circuit provides a reference voltage of 2.5 V adjusted in the trimpot. The transistor can be the BC558 (in the drawing it came out as NPN). The control is done by a rectangular input signal.
This circuit was found in the September 1976 issue of Radio Electronics magazine. The circuit is...
We found this circuit in a 1995 documentation. It operates in the 3.5 MHz band that corresponds to the 80...
This 3-decade operating range VCO was found in a 90s Popular Electronics. The circuit uses...