This circuit was obtained from an American 80's documentation. The balanced mixer can be shown in CB4234. The circuit is for controlling RF signals in a modulation system.
This version of the Pierce oscillator with the 2N3904 was found in the January 1994 issue of...
The traditional configuration of a non-inverting amplifier with the operational 741 shown in the...
This circuit is from a Radio Electronics from January 1958. The transistor is the CK722, and the...