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 farnell.com 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 www.talkingelectronics.com 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.