This receiver uses old transistors that are equivalent to BC548 and BC558. The photo diode is of any type. The receiver can be used on a highly sensitive audio link.
Here is a very simple robot circuit that follows the line driven by a small 3 V sevomotor that...
This circuit, which provides a power of up to 3.5 W, can be supplied with voltages from 9 to 14 V....
This circuit transmits the signal taken from a telephone line to a receiver placed nearby (up to a...