so I have an electric car, it's going to be in a parade tonght. I want to run a projector off of it. Have 12 12v batteries in series.
I will not need a transformer, but I'm wondering what voltage to tap off at ( 10series, 120v?) and what type of wave would be best to program to arduino. I have some 200v 180a mosfets to use for an h bridge. I'm sortof wondering the best was to program some offset pwm signals.
Are you trying to run a 120VAC projector off of 12VDC batterys? If so, you would probably be better off getting something like below.
I'm postng here because I want to make my own. Also, sadly my favorite hardwafe store is not within an hour of purdue. The projector needs about 300watts.
I already have the components, jusst need to write the code and decide on my input voltage
You do not have enough voltage in the system, unless you want to also build in a step-up converter. A 120VAC system actually peaks at 169V (square root of 2 times 120V). The "type of wave" is one which uses PWM to generate a sinusoid at 60 Hz, switching direction at 120 Hz. This would go to your H-bridge followed by some serious filtering to get rid of the switching effects of the bridge and smooth out the waveform to a clean sinusoidal AC signal.
This is not a simple undertaking and the potential for damage to your components and yourself is large. I think the best "type of wave" for this project is waving goodbye and buying an off-the-shelf inverter. Especially if you plan on having this done by tonight!
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The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, light sensor, potentiometers, pushbuttons
most of the shelf inverters use a square wave or modified square wave which would not require 169v. Very few are true sin inverters. I already tested running the projector off a 200w square wave inverter and it worked. But the inverter could not sustain the power.
Ok, one day may have been slightly unreasonable. But, I almost finished it on Friday, I just didnt have a chance to get to an oscope. I ended up hooking up a 200w store bought inverter(not enough for projector, but we had speakers).
Now I connected th 200w inverter to the oscope to see the waveform. It uses a modified square wave.
Their wave peaks at 150v, which will be perfect. My pack averages 145-155 volts. I try not to drive below 144, it is very hard on the batteries.
I wrote a program to output a 60hz square wave on the arduino. Working on one for the modified wave. I hope to have something working soon so It'll be ready next time.
This is preliminary, clearly nothing is mounted to anything, and the HV side is not powered
Thanks for the help
Wow, and you're doing this on a breadboard!? That is optimistic 
It almost sounds like the potential for a TV game show: Build an inverter in one day with an Arduino and a random collection of electronics.
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The Quick Shield: breakout all 28 pins to quick-connect terminals
