This circuit was found in a 1967 General Electric documentation. Tunnel diodes can oscillate at very high frequencies. These are not currently easy to obtain components.
Found in an Electronic Design from the 90's, this circuit uses common components. The circuit is...
When the sensor receives light, the relay closes its contacts and remains so even after the light...
This circuit produces pulses of 90 V at intervals that can reach 5 minutes. The circuit is from a...