This circuit was obtained from Popular Electronics from June 1978. It doubles the input DC voltage. Obtained current is very low, serving only for polarization circuits.
This 1970s RCA circuit can be triggered by light or dark, depending on how the LDR is connected....
Found in a 1969 documentation, this circuit for the 20 MHz band does not use a transformer. The circuit is...
This circuit was suggested by Linear Technology in a 1980s documentation. The setting applies to...