This circuit was found in a National Semiconductor manual from the 1980s. The operational amplifier is from that time and the waveforms are shown in the diagram.
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...