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 circuit is from an August 1984 Radio Electronics magazine. It monitors the state of a RAM...
In the figure we have the way to obtain an adjustable constant current source of 2 mA. The...
Found in a Maxim publication from the 90s, this circuit generates signals from 10 to 25 kHz with a...