This circuit uses an unusual operational amplifier nowadays and has a very low consumption. The number in parentheses corresponds to the second channel, for a stereo version.
Instead of LED bulbs, LEDs with a series 470 ohm 1k resistor can be used in this 80's circuit....
In the figure we have the way to implement a 3-Input logic function OR inputs using common diodes....
This circuit is from Radio Electronics from July 1983. The operational amplifier is of the...