Solar intercom (CB20503E)

This circuit can be used in demonstrations or science fairs. The circuit uses headphones and can be powered by solar cells.

Alternating Flasher (CB6252E)
This circuit, which appears at other times on this site has this version obtained in a Hands On of...
Experimental Volume Control (CB4560E)
This circuit was obtained from an Auguist 1974 Everyday Electronics magazine. The circuit is still...
Volume Expander (CB22155E)
This circuit was found in an English publication from 1989. The integrated circuits are of the...