The circuit shown is from the 1994 Linear Applications Handbook by National Semiconductor. Some of the components are not currently common and should be looked for equivalents.
This circuit provides good audio power to a box that contains a heavy speaker of at least 8...
This circuit was obtained in a 1967 General Electric manual. The circuit applies to other triacs....
This circuit with the 741 operational amplifier was found in the March 1995 issue of Electronics Now...