This circuit activates a relay when the supply voltage drops below the value set in the trimpot. The transistors can be the BC548 and BC558 and the 6 V relay. The circuit was found in a 1999 Poptronics.
This circuit, which can be used as a shield for microcontrollers, provides 50% active cycle output...
We found this circuit in a 1968 General Electric publication. The circuit uses an SCR of the time,...
This circuit allows the division of the frequency generated by an oscillator with the 4069 by two,...