This amplifier is from the Philips Databook of 1990. The circuit is suitable for automotive use and has the characteristics given in the table below the diagram.
This circuit of an Electronics Hobbyists Handbook uses a different configuration for a triac. The...
We found this circuit in the July 1988 Radio Electronics magazine. The frequencies are given by...
Found in an English documentation from the 90's, this circuit makes slow logical pulses audible,...