This circuit was found in a 1980s documentation. The diodes may be general purpose diodes such as 1N34 or 1N60 and the indicator may be the lowest current range of a multimeter.
This small locator transmitter was found in old Radio Shack documentation. The transistor could be a...
This circuit was found in the October 1994 issue of Electronics Now magazine. The 4046 PLL is not...
The sensors of this liquid alarm are formed by two pieces of wire with the ends peeled off. The...