This low power circuit can be powered with voltages from 1.8 V. We find it in a 80s Hands On Electronics. The load can be from 8 to 32 ohm.
This interesting capacitive water level sensor was found in Popular Electronics. The circuit can be...
Using transistors at the time, this circuit was found in a 1967 Ferranti documentation. The...
This circuit locks when the sensors are opened. The relay can be 6 or 12 V depending on the power...