This simple transistor tester was found in a Japanese magazine in 1967. It tests general purpose transistors of both the NPN and PNP type and is powered by 4 batteries (6 V).
This circuit activates a relay when the water reaches the sensors. The circuit is from a magazine...
The circuit, from Motorola's 1993 Linear Interface ICs, uses an unusual operating system today....
Decade counters, such as the 4017, can be cascaded as sourcing signals with the frequency divided...