# Crazy Sound Light

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## Introduction: Crazy Sound Light

In this Instructable you will be simulating a sound light system.

The system in this instructable needs a battery. Another system without the battery is shown here:

https://www.instructables.com/id/Simple-Sound-Ligh...

This simple sound light system might need a high amplitude input due to a lack of amplification. You can purchase Class D amplifiers on eBay, Amazon or Aliexpress websites and connect them to this circuit. Class D amplifiers are very efficient and do not require much power when compared to Class A or Class B amplifiers.

However, a high amplitude signal for this Instructable is not as essential as for the circuit shown in the link above because of the DC voltage source that is not present in the other Instructable.

I never made this circuit because I am concerned about the current from 9 V battery flowing into the music source and damaging the amplifier. I believe that this circuit might work with a 4.5 V source.

The variable resistor, R1a is used for brightness control.

### Supplies:

Simulation Software. This could be online and software that you download and install. I used old PSpice Student Simulation software only to reduce the circuit drawing due to keyboard short cuts that modern software does not allow.

### Teacher Notes

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## Step 1: Draw the Circuit

I used old PSpice software to save time.

If you are going to build this circuit you do not need this many capacitors and switches. Try to see which capacitor gives you the best response.

The current across the LED must be no more than about 10 mA.

## Step 2: Simulate the Circuit

I press F11 on my keyboard to simulate the circuit. You can see that the voltage is slowly increasing over 1 second.

Lower capacitor values will allow the LED to turn on quicker.

Simulations show that the current across the LED is only about 3.5 mA. This is because I used high resistor values. Practical tests that show a bright LED can still work at such a small current. However, the light might very dim.

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