Found in a 1967 American publication, this circuit with feedback for two transistors has a gain of 20 times. Phototransistors are types of the time.
This simple circuit has its trigger point set in the trimpot. The transistor can be any general...
This traditional triplier configuration with the 555 can be found in other articles on the...
This circuit is from a 1977 documentation. It is powered by the power supply of the circuit under...