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 generates 500 Hz rectangular signals. The circuit is from old American documentation. Neon...
The circuit shown is a documentation on 80's tunnel diodes. The frequency depends on the delay line...
In the figure we have a small general-purpose amplifier with the LM386 integrated circuit and...