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 circuit is from an Electronics World of 1967. The circuit slows down the activation of a...
This metal detector circuit uses an AM radio as an indicator. The radio is placed off-station and tuned...
In the figure we have a sensor circuit that makes use of common transistors and a photo diode as...