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 is the modulator circuit for the remote-control transmitter presented in CIR11801. The...
This circuit was found in an English documentation from 1969. The transistors are of the time,...
This circuit also makes use of a field effect transistor (JFET) which can be the BF245 and has an...