This dual-LED circuit indicates three signal levels. It was found in the January 1996 issue of Electronics Now magazine. The integrated circuit may be an LM339 or another comparator.
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...