Filament source (T398E)

Despite being transistorized, this is a constant current source circuit for 1 V valve filaments such as the 1H4 tube.

10 to 100 seconds time switch (CB20371E)
This circuit was obtained in a documentation from the 1970s. What it does is to delay trigger a...
Transistor gain test (CB20733E)
With this circuit it is possible to make the selection of transistors and their test according to the...
TTL Memory 7400 (CB22412E)
This memory flip-flop must be powered by 5V voltage. The circuit stores 1 bit. ...