I'm trying to find a device that will produce a midi note when voltage is supplied to the device. Anyone know of anything such as this or can steer me in the right direction? Thanks

What are you trying to accomplish? Do you want to build your own MIDI controller?
I know there are several different kinds of controllers already out there.

I'm trying to build a sensor that when it is tripped once it will send a specific midi note to my lighting board either motion sensor or better yet some sort of beam that gets crossed, and when it is tripped a second time it will second a second note that is different from the first. My intention is to have the sensor activate a program that i create on my lighting console, then when the sensor is tripped again activate a second program on my controller. So I would need the midi note to alternate each time. I'm just have a hard time figuring out how to actually accomplish this. Any help is appreciated.... I have very limited knowledge in regards to midi...

Sounds complex man, even with my 3 years experience with MIDI, and some eletronics knowledge. If you were looking for some sort of control surface for this...heres one. This site has a general summary of voltage control with MIDI (about halfway down the page)...hope this helps

Ro that first link you posted what kind of device actually is that? Using that would I be able to take a device that emits a positive pulse wire it to that unit and have that unit then send a midi note/channel?

Bill, I believe I need to construct a midi controller... i'm not sure if thats the right terminology but i believe it is. I have all the electronics aspects worked out. I just need a way of converting positiv voltage and a zero voltage reading to transmit a different midi note/channel

Hmmm. A MIDI drum controller comes to mind here. The inputs on a drum controller could probably work for you. Just a matter of finding the right one. Most, I believe, use 0 volts for "off", and a varying amount of voltage depending on how hard a pad was hit. You would probably have to have two sensors, though. One for each note.

Try this: http://www.paia.com/midibrn.htm

And this for general controller info: http://www.synthzone.com/ctrlr.htm

Or try a Google search on "MIDI drum controller"