This sound controlled lights circuit design is used to control the brightness of the lights attached to it in sync with the sound that is being capturated by its microphone. This electronic circuit design is very common in disco houses, bars, parties …
Usually, sound controlled lights are just connected in parallel with the loudspeakers. This configuration has two disadvantages: first, a very power amplifier can destroy the lights or worse, a defective light can destroy the amp. This problem is avoided by the circuit by not connecting directly to the amp. Instead, it picks up the sound with its microphone.
The power supply part is on the left of the electret microphone amplifier and the light controller part is on the right. The capacitors C2 and C3 are the capacitive voltage divider and reduces the power supply level. Diodes D1 and D2 rectify the positive swing of the AC voltage. The network composed of L1 and C1 protects the power line from voltages surges. In this circuit design, an electret microphone is being used. Take note that there are 2 types of electret mics. The first type has three pins for power, ground, and output. The second type has only two pins. The second type is used for this circuit.
In building this sound controlled lights circuit, take note that you are dealing with strong voltages and currents. The components used must have enough ratings to deal with those.
The potentiometer P1, P2 and P3 must have plastic shafts and knobs. Use a shielded cable to connect the microphone to the circuit .
All wirings going to the main supply and lights must be isolated with shrink tubings. The case for the circuit must be made of plastic. Do not let anything metallic protrude out of the box.
Even the heatsinks for the triacs are electrified. Beware that there is no isolation between this circuit and the main power lines. The maximum power output of each outpuc (triac) is 400 watts, do not exceed that level!