This configuration was found in an English magazine from 1965. It is valid for any junction FET. The input impedance is 5.5 M ohm higher than conventional stages.
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...