This conventional 4 channel circuit with the 4017 and 555 was found in the November 1991 Radio Electronics magazine. The potentiometer can be 47k and it controls the speed of the effect.
This high impedance and low capacitance buffer employs a junction FET that can be BF245 or...
This circuit was found in an American documentation from 1966. The transistors are from that time...
This circuit for the 85 to 95 MHz band has a gain of 15 dB. We find it in a 1980s documentation. The...