# Arduino LED Voltage Meter

For my Gr 12 Physics project we are assigned to build a cannon. I have built a coil-cannon using disposable cameras. I was wondering how I could possibly make a voltage meter (kind of like a VU Meter) using LEDs and an Arduino Uno. For now I'm using a multimeter to know when to stop charging the capacitors, but I'd like to have LEDs as well.

Sam

Well first you have to determine what the voltage range subject to be measured. The Analog input pins for an Arduino can only handle a 0-5vdc range without damage to the chip. Once you know the absolute maximum voltage, you can then calculate a voltage divider with a couple of resistors so that the voltage is scaled to a 0-5vdc range.

Then its just a matter of reading the analog input pin, scaling the reading to the number of LEDs you are going to use and then outputting the proper bits to the LED array. Should be a pretty good project for starting to learning C/C++ on a Arduino.

Lefty

That really is looking at solving a problem in an expensive way.

If all you want to see is a certain voltage being reached then use a simple zener diode, resistor and LED.

If you want to see a varying voltage then use an LM3914 circuit. See the attached for full details
http://www.national.com/mpf/LM/LM3914.html

jack

These are some of it

I'm not sure which option would be the easiest, but I'm leaning towards what retrolefty suggested. I forgot to mention the voltage range. I'll be measuring from 0 to 330 V (since that's the max voltage for a flash capacitor). Are there any other alternatives? If not, could someone kindly provide more detail on what retrolefty said?