This simple diode test appears at other points in this section. Or circuit can be adapted to use LEDs instead of ordinary lamps.
This circuit was found in an old GE manual. It uses a thermocouple as a sensor. The SCR must be in...
This circuit was found in an English magazine from August 1982, but it can be easily assembled with...
This is the circuit of the commercial Japanese megaphone of the 60s model DM-218. The circuit uses...