cheap slave for homemade lighting device?

I've been using an overhead projector to project transparencies onto

subjects, but have found myself limited by the light output - using

ISO 100, 1/60th I'm stuck at (f)2.0. My idea is to put a flash (an old

Vivitar 2800) inside the projector and tether it to a slave of some

kind that is attached to the outside of the projector.

 

Only, I know nothing about wireless triggers. The Wein Peanut slave

seems like a good price range, but it doesn't look like these can

attach to a hot-shoe-only flash (and while I'm not sure, I think these

are triggered by other flashes, which I'm guessing is what the term

Optical Slave means).

 

I've been using cords so far, and I'm thinking this might be a good

excuse to start looking at wireless strobe solutions in general. I

splurged a while ago and bought some Patterson Interfit 300s, and I

have a Vivitar 285. I've seen some really nice photography done with

just a 285 and a wireless trigger, it'd be nice to find a system that

allows me to mix and match all my "real" strobes with these homemade

ones I'm building.

If you get a hotshoe to PC adapter then you can plug a PC cable or anything else that plugs into a PC plug into your hotshoe flash. Then you can get a wireless system and plug it.