Tube negative ion generator (CB21002E)

This circuit was found in an old American magazine for radio amateurs. The circuit is based on a very high voltage tube of the time.

| Clique na imagem para ampliar |

Bistable Sonic Relay (CB18272E)
With the configuration shown in the figure, we have the relay being activated when the microphone picks...
Pulse Generator (CB18236E)
This TTL generator that can function as a control shield or external clock for microcontrollers was found in...
Absolute Value Circuit (CB19719E)
The OP07 operational amplifier is not common today, as the circuit is from an old European manual....