This circuit also detects IR, providing LED indication. The circuit is used to indicate humidity in bench tests. We found it in the Radio Electronics magazine of February 1990.
We show an oscillator that produces rectangular TTL signals based on inverters. Inverters can also be...
I got this circuit from a magazine in 1967. The magazine no longer exists, but the circuit that...
This egg timer has been found in an English magazine that no longer exists in 1982. The...