This kind of LED flashes with music, which is similar to the level indicator of audio equipment in effect. There are many circuits, which can be discrete components or ready-made IC, as shown in the figure: This figure can connect 2 1 LED, arranged to flash to both sides, and the middle LED is long and bright, serving as a power indicator. The input end is connected with an audio signal, the signal is weak, the LED flashes less, the signal is strong, and the LED flashes more until it flashes to the end.

Make the LED light flash with the music rhythm;

LED lamps can control their power supply through switching circuits, such as triode switching circuits and gate turn-off thyristor circuits. The problem is to obtain a control voltage that varies with music to control the switch circuit connected to the LED lamp to turn the lamp on and off. The control voltage can be a voltage comparison circuit, such as two triode switching circuits with LED lamps as the load, in which the base preset bias voltages are different. When the audio output voltage is coupled to the bases of these two circuits through capacitors at the same time, the one with higher bias voltage will be turned on when it gets a slightly lower audio voltage, which corresponds to the lighting of led lamps, while the one with lower bias voltage needs a larger audio voltage to light up; In this way, the two lights can flash with the output size; Or, if two switching circuits with equal bias are driven by high-frequency and low-frequency dividers respectively, the switching circuits are controlled by voltages with different frequencies, and the lamp flashes with the frequency.

In fact, there is a ready-made LED light flashing circuit with output volume control, see the attached figure from the network;

If the power of the colored lamp is high, it can be used to control the solid-state relay and expand the output power.