We found this code switch circuit in the January 1999 Electronics Now magazine. Some of the components are integrated circuits from that era.
This is the normal configuration for the TDA2003 integrated circuit, an amplifier that can provide 10...
Found in an English publication from 1977, this circuit uses only 1 LED. Unlit means heads and lit...
In the figure we have the transmitter and the receiver for an optical audio link via infrared. The...