This circuit was found in documentation from the 90s. The operational amplifier admits an equivalent. The circuit has frequency ranges up to 5kHz determined by R1.
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...