This circuit was found in an American documentation of the 90s. Optical resources with the LDR as a lens can help in obtaining directivity and sensitivity.
Intended for use with signals from tape recorder pickups, this circuit was found in the December 1972...
In the figure we have the configuration of a voltage regulator with 3 transistors. The components depend...
This circuit was found in an 80s documentation. The integrated circuit used is from that time,...