This circuit was obtained in an old Popular Electronics. It makes use of quite common components. The speed of the effect is set to R7. The circuit drives 20 LEDs.
This circuit uses unusual operational amplifiers, but equivalents can be tried. FETs can also be...
This circuit was obtained in a 1991 publication. What it does is to amplify a signal with unit...
This small digital transmitter uses a 1 MHz crystal, or another nearby frequency, to produce a...