The S-meter is a signal strength meter used in communication receivers. This circuit was found in a 303 Circuits from the 90s, European publication.
This experimental amplifier was found in the 1960 Mullard transistor reference manual. The...
This circuit from Motorola is from 1968, appearing elsewhere on this site. The transistors admit...
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...