This adjustable frequency circuit was found in December 1986, Radio Electronics magazine. The base frequency is given by C1 and the power supply must be 5 V.
This circuit is from a 1997 English magazine, but it is very current due to the components it...
This system of sequential LEDs has its speed adjusted in a 1 M ohm potentiometer and this speed...
This is the commercial circuit for the TRF-44 amplifier sold in Japan in the 1960s. The circuit...