The configuration shown was found in an old Poptronics but can be easily assembled using a common calculator photocell. The relay is according to the supply voltage.
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...