This array of active filters will convert the audio signal from a small radio or tape player into a flickering pattern of colors. R2 controls gain of the input amplifier below. Use radio/tape player volume control and R2 to adjust intensity of LEDs.
- Insert phone plug connected to T1 part way in phone jack so speaker will not be switched off.
Leds vary in brightness. Experiment with different leds for best results. Here is actual response of circuit :
Reduce R4 and R7 to increase red and yellow brightness. Increase R11 to increase green brightness.