This interface shield circuit is from the 1983 Intersil Databook. The components used are uncommon today. ADCs are low-cost digital converters. The power source voltage must be 5 V.
This 7400 TTL circuit has a memory, keeping the LED on when a pulse is detected. The circuit must be...
This circuit is from a 1995 Electronics Now. It generates a 1 kHz sinusoidal signal. See in the...
We found this circuit in an old documentation for radio amateurs. The transistor can be any PNP of...