Sound to Light Meter




I started making this circuit as I was in the process of making an operational amp for a Pringle tub Speaker system which I actually really enjoyed using and making and wanted to incorporate lights into is as a portable all around music system.

This is the prototype VU meter on a breadboard powered by a 9v battery.

Here it is>

I was very proud of this as it took a lot of research as I was fairly new to electronic circuits at this time.

Step 1: Learning What Is What

When researching I came across the Vellemans website and upon it I found the Pocket VU meter circuit with it the above schematics. This is not the one I chose but the one I learnt from.

Although they do sell the kits which are brilliant if you want to just have it now I tried to understand why the circuit was made and why each part was needed so I set out to find out the facts of each part used and how it operated.

I would like to save you some time if you are planning on taking the same path as myself or already have knowledge. The BC547 is a simple small use NPN transistor and the Input was a 2 pin Electret Condenser Microphone.

Also BAT85 is a 113 Small Signal Schottky Diode, Single, 30 V, 200 mA, 800 mV, 5 A, 125 °C as informs me.

Once I had understood what was what the Vellemans circuit was a good starting point but

I WANTED MORE LIGHTS DAMMIT!!!!!!!!!!!!!!!!!!!!!!

Step 2: Chosen Schematics

Credit for this circuit schematics is given to as I found their schematics on Google and found it easy to follow with a few helpful tips. Thank you talking electronics.

I chose this schematics for the main purpose of increased LED output and the ease of building.

It was build at night after a days work and with tiredness some problems of crossed wires did occur but after a good night sleep they was obvious and easy to spot.

The next step would be to incorporate this circuit with a few relays and this could be adapted to control mains powered lighting to create a larger and brighter display.

Hopefully you will use this to light up your project like this will do to mine.

Thank you for reading.



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    2 Discussions


    3 years ago

    here 3 variables A B and C how can I attach a mic on 3 inputs .. (A for positive and B , C of negative ??)


    3 years ago

    Both schematics work fine.

    Two quad comparators driven by a couple of transistors or an opamp will do the job, I would say more "elegantly".