Found in July 1975, Radio Electronics magazine this circuit can use any operating circuit, including the 741. The circuit must use a symmetrical power source.
This circuit is recommended for alarm systems since it has a good output stage. The circuit is...
) Suggested by Philips in a 1968 documentation this circuit has very high 10 ohm on-load voltage...
No information is given about the transformers in this circuit suggested by Motorola in a 1968...