This circuit was obtained from an American documentation from 1976. The circuit can be adapted to modern TTL components and used as a shield.
This Philips circuit of the 70's makes use of components of the time. The DZD40 is an uncommon...
This circuit with two operating modes was found in the September 1989 issue of Radio Electronics...
This circuit is from an old documentation making use of a 3,579,645 MHz analog color television...