This circuit triggers a buzzer or other warning device when the light falling on the sensor is cut off. We found it in the Encyclopedia of Electronic Circuits Volume 5 of 1995.
Motorola's integrated circuit used in this' 70s amplifier is no longer common today. Neither do...
This circuit activates a relay when the phone rings allowing the control of a warning lamp or even...
Found in a 1969 British publication, this circuit uses a regenerative switch with two transistors to...