This circuit provides 2.5 W of power with 6 V supply and 4-ohm speaker. We found it in the Radio Electronics magazine of April 1990.
Suggested by Raytheon in 1967 documentation this circuit uses a lightbulb and LDR optical coupler of the...
Found in American documentation from the 90's, this circuit consists of a solid state relay with...
Indicated to be used at the sensor input of a PC, this circuit was found in an English...