Yes, it’s worn by the actors, usually in the small of their back. I’ll go ahead and tell you the show, it’s called Bengal Tiger at the Baghdad Zoo, currently running on Broadway, starring Robin Williams. Robin is wearing one of the rigs in the first scene of the show, his character gets shot three times in the chest, so three spots of blood spontaneously appear after he’s “shot” by a gold plated Desert Eagle. To answer your questions:
-12v supply is simply a 9v and two AAs wired in series. They power both the board and the solenoid. Right now we go through 3 9vs and 6 AAs per performance, so that’s another reason I want to go smaller, so I can use a small rechargeable battery, for the waste factor, the cost, and the size. Biggest cause of power failure: bent 9v clips.
-about 14oz blood, in a Nalgene bottle flask.
-At 125 it can shoot like a fountain, but I have a pressure regulator in the system that takes the pressure down to between 30-50psi, depending on the effect.
-All 4 units can be used at once, but they aren’t at the moment. They do not interfere with each other at all, and in fact the remote transmitter/receivers can be swapped in case of failure, so each unit can be used as a backup for another.
Yeah, the board has way more functionality than I need, which is another motivating factor for finding something simpler and smaller. I have looked and looked, and the only thing I can find commercially that’s even close is a remote for a camera flash. Which is why I’ve gone down this road of figuring something out for myself. My electronics skill is limited and mostly self taught. I can do basic hacking of existing electronics pretty well (you should see some of the wack things I’ve done with a salvaged flash from a disposable camera), but this stuff is beyond my skill level, though I’m working to change that. I’m starting to get involved with the Maker community here in Minneapolis where I live, and have starting doing some active research and education (did you know that MIT has an electronics course available on iTunes University?).
Any tips on getting up to speed on this technology would be greatly appreciated. And if there’s interest I could post some pics and possibly some video of the blood rig in use.