This circuit was found in the March 1997 Electronics Now magazine. It uses a common analog indicator and the transistor is a general purpose one.
Available at Mouser Electronics this component of Diodes Incorporated consists of a voltage...
Found in Radio Electronics this circuit uses a fotodiac to drive a triac. The circuit can use...
The first circuit was suggested by Analog Devices (www.analog.com) in its Application Note AN-411...