Found in a PE Hobbyst Handbook, this circuit checks if there is voltage in a power outlet by emitting sound and lighting an LED.
This simple 1 transistor circuit was found in an American documentation from the 60's. The...
Found in a magazine 73 for radio amateurs, this circuit makes use of general purpose transistors and...
The presented circuit allows to control the valve of a tap. The positioning of the emitter and the...