This circuit was found in the September 1971 Radio Electronics magazine. The buzzer can be replaced by a relay according to the supply voltage. R1 adjusts the sensitivity.
This circuit can be used in a single optical link or optical communication system and even using an...
This circuit was found in an old Motorola documentation from the 70s, as it uses one of its...
Found in a 90s 73 magazine, this circuit provides an output of 1.5 A with 24 V from a 12 V source....