This circuit was found in a 90s Popular Electronics. The circuit uses 4 bicolor LEDs to indicate signals of both TTL and CMOS logic. The circuit is powered by the source of the circuit under test.
This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit...
In the figure we have the way to implement a sinusoidal oscillator with the 4093 IC. The component...
Equivalent transistors, like the BC548 and BC558 pair can be used in this circuit that we find in an...