In this circuit the LED lights up when the voltage drops below the value set in the trimpot. The transistors can be the BC548. The circuit is from a 1999 American publication.
This control circuit for incandescent lamps was found in a publication from the 90s. The circuit uses...
The power supply for this circuit must be symmetrical at 12 + 12 V and the load must be 8 ohms. The...
This practical two-transistor linear motor control idea was found in the September 1962 Radio...