Found in a PE Hobbyst Handbook, this circuit checks if there is voltage in a power outlet by emitting sound and lighting an LED.
Placed in the vicinity of a telegraphic transmitter (CW), this circuit produces an audible signal on...
This circuit for light data transmission (visible or IR) has a maximum speed of 1 Mbps and can be...
This circuit aims to recover electrolytic capacitors by applying currents higher than normal for a...