This circuit, which can be used as a shield, was found in Radio Electronics from the 90s. The operating circuit can be replaced by a lower voltage equivalent.
This circuit is from the National Semiconductor 1977 FET Databook. The FET can be BF245 or MPF102...
This 32 A circuit uses SCRs of the time. We found it in a 90s General Electric documentation. The...
This tone control was obtained in the Audio Handbook of the National Semiconductor of 1977. The...