Simple Sound to Light Converter Circuit

Assume you have a disco party, but without flashing lights!

This sound to light converter circuit acts like a translator between sound and light.

It listens to music and turns those sounds into flashing lights, making your room light up along with the beat.

It uses clever parts to change the volume or pitch of the sound into how bright or fast the lights flash.

Circuit Working of Sound to Light Converter Circuit using Piezo:

Parts List:

The above circuit is a sound to light converter circuit that uses three transistors to amplify and rectify the audio signal from a piezo to control the brightness of an LED.

Piezo Converts sound waves into electrical signals.

Transistor Q1 preamplifier stage.

Amplifies the weak microphone signal.

Capacitor C1 blocks any DC voltage from the microphone and only allow the AC audio signal to pass through.

Resistor R1 sets the bias current for the transistor.

Capacitor C2 Coupling capacitor.

Blocks DC voltage but allows AC signal to pass through.

It couples the amplified signal from Q1 to the base of transistor Q2.

Transistor Q2 is a second amplification stage.

This transistor further amplifies the audio signal from Q1.

Resistor R3 sets the bias current for Q2.

Resistor R4 nd R5 Voltage divider circuit.

Sets the bias voltage at the base of transistor Q3 BC547 which controls its switching point.

Transistor Q3 rectifier stage.

Converts the amplified AC audio signal from Q2 into a pulsating DC voltage.

When the voltage at the base of Q3 is above a certain level the transistor conducts and allows current to flow through the LED making it light up.

The brighter the audio signal, the more the LED will light up.

How to Build Sound to Light Converter Circuit using Piezo:

To build a sound to light converter circuit using piezo follow the steps:

• Connect transistor Q1 collector to positive supply through resistor R2.
• Connect transistor Q1 base to piezo.
• Connect transistor Q1 emitter to ground through capacitor C1.
• Connect transistor Q2 collector to ground through resistor R4.
• Connect transistor Q2 base to collector of transistor Q1.
• Connect transistor Q2 emitter to positive supply.
• Connect transistor Q3 collector to positive supply through Red LED.
• Connect transistor Q3 base to emitter of transistor Q1 through resistor R3.
• Connect transistor Q3 emitter to ground.

Circuit Working of Sound to Light Converter Circuit using Electret Mic:

Parts List:

The above circuit is sound to light converter circuit using electret Mic:

Electret Microphone  convert sound waves into a small AC voltage.

This voltage is very weak and needs to be amplified before it can be used to control the LED.

There are three transistors Q1, Q2 and Q3 to amplify the weak signal from the electret microphone.

Q1 and Q2 are configured in a common emitter amplifier circuit which increases the voltage of the signal.

Q3 is configured as an emitter follower which provides additional gain and converts the high impedance signal to a low impedance signal suitable for driving the LED.

Capacitor C1 is used to block DC voltages and allow only the AC signal to pass through the circuit.

C1 blocks DC voltage from the power supply from reaching the microphone.

Resistors R1 to R6 set the gain of the amplifier stages and bias the transistors for proper operation.

R1 sets the bias current for Q1.

R2 and R3 form a voltage divider that sets the bias voltage for the base of Q1.

R4 sets the bias current for Q2.

R5 sets the bias voltage for the base of Q2.

R6 limits the current through the LED.

The LED is the output of the circuit.

The brightness of the LED will vary depending on the intensity of the sound picked up by the electret microphone.

Formulas:

It is necessary to comprehend the fundamentals of amplification utilizing a transistor based circuit in order to design an amplifier for an electret microphone.

The following is a general framework and formula for creating an amplifier for an electret microphone:

Amplifier Based on Transistors:

The voltage gain Av for a common emitter transistor amplifier may be roughly calculated as follows:

A_v​ = −R_C​​ / r_e​

where,

• The transistors intrinsic emitter resistance is denoted by re, while the collector resistor is represented by RC.

When designing an electret microphone amplifier, consideration must be given to the individual application, such as audio recording or sensor applications in order to balance power consumption, noise performance, and gain.

How to build Sound to Light Converter Circuit using Electret Mic:

To build a Sound to Light Converter Circuit using Electret Mic follow the below mentioned steps:

• Connect transistor Q1 collector to positive supply through resistor R3.
• Connect transistor Q1 base to capacitor C1.
• Connect transistor Q1 emitter to ground.
• Connect transistor Q2 collector to positive supply through resistor R4.
• Connect transistor Q2 base to collector of transistor Q1.
• Connect transistor Q2 emitter to ground.
• Connect transistor Q3 collector to ground through series of Red LED and resistor R6.
• Connect transistor Q3 base to collector of transistor Q2 through resistor R5.
• Connect transistor Q3 emitter to positive supply of 6V battery.
• Connect in series resistor R1 and Electret Mic from positive supply to ground.

Note:

• Be aware that building electronic circuits can be dangerous if not done properly.
• Make sure you understand the risks and take appropriate safety precautions before attempting to build this circuit yourself.

Conclusion:

Sound to light converter circuits bridge the gap between sound and light offering a fascinating introduction to electronic.

While basic versions provide a simple response to sound intensity more complex circuits can create dazzling light shows or even accessibility tools.

So grab your tools and get ready to see sound in a whole new light.

References:

Converting sound to light

Light to Sound Converter