This circuit is from an 80's Electronic Engineering. The base is a common operating and 4 single integrated voltage comparators. The circuit directly drives 4 indicator LEDs.
This loop antenna was found in a 1990s documentation. The circuit includes a field strength meter. The...
This circuit generates signals for adjustments in FIs of 10.7 MHz. The transistors can be BC548 or...
The circuit shown below was found in the National Semiconductor Linear Applications Handbook...