The circuit shown was found in the February 1994 issue of Electronics Now magazine. The circuit records messages for a few seconds and plays them back as keys are selected.
This circuit uses a 741 operational amplifier that must be powered by a symmetrical source of 6 to...
This oscillator generates a 1 kHz signal, using an old germanium PNP transistor. The circuit was...
This circuit was obtained from a Radio Electronics issue from January 1989. The indicator is a...