FET photo control (CB8269E)

This circuit is from a 1966 American documentation. The circuit uses a photo-FET, an unusual component today.

| Clique na imagem para ampliar |

Digital Volume Control Treble and Bass Balance (CB4576E)
This circuit is from 1995 documentation. Integrated circuits are used which can still be found...
Crystal Test (CB13945E)
We found this 50 kHz 25 MHz crystal tester in a 1978 QST magazine. The FET can be the BF245 and...
Opto relay using two couplers (CB7414E)
This circuit was found in General Electric documentation from the 1980s. The circuit uses couplers...