Protect your amplifier by overload, through maximum output it takes out from the amplifier. This will damage the amplifier system and speakers. Kids may blow up the amplifier when the parents are not at home, in this situation you can use this to protect the amplifier.
The amplifier working in its 100 percentage efficiency will damage the IC or internal circuit of your amplifier. Sometimes you would like to play the audio in maximum sound but this damages the speaker also by clipping or distortion coming from the audio amplifier.
Circuit Diagram
Selection of R3 Resistor
Working
The circuit will protect your amplifier from receiving maximum audio from input to the amplifier circuit. If you increase the volume the circuit will automatically reduce the gain and maintain the steady state of audio signal to the amplifier.
In this circuit the gain of the amplifier is automatically controlled by the LDR (Light dependent resistor). For the automatic audio controlling setup the LDR is enough, it has some important and useful qualities for this audio project.
The main advantage of this circuit is less distorted sound on the output section, even when the volume is turned up high. The LDR is sensitive to the light, when the maximum level of audio is reached (Audio output limit) the LED light turns on .
Once the maximum volume level is reached, the small increase of amplifier power in the output triggers the transistor to turn on and also turn on the LED connected with it. The light fall on the LDR and reduces the resistance of it.
The LDR resistance is reducing means it conducts more charges through it. The LDR is connected with the ground supply so the light falling on the LDR will pass the negative charge to the audio amplifier input section and reduce the volume or audio gain.
Setup of LDR
You can put the whole circuit inside the amplifier cabin or small external box. It is better to keep inside the amplifier cabin. You must be careful to prevent the amplifier output signal from going back to the input; this will overheat the amplifier and also damage it.
The physical setup involves a clear plastic rod, like perspex where you need to glue the LDR at the one end. To prevent the amplifier output from causing trouble, you need to carefully project the light and the LDR don’t no other light from the outside.
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