Metal locator (CB7506E)

This simple metal detector was found in a 1960 Sylvania transistor manual. The phone must be high impedance or crystal.

Regulator LM100 (CB19501E)
The LM100 integrated circuit is quite old, still of a metallic enclosure type. The circuit shown in...
Remote Gain Circuit (CB21072E)
Found in an Electronic Design from the 90s, this circuit makes use of components from the time. The...
Continuity Tester (CB11846E)
This circuit is from an Italian magazine of 1983, but it can be assembled with the most modern...