The GM-20 is by far the best way to go for a shutter. Its not spring loaded though, it uses a torsion bar, which can break if it gets stressed too much. I've seen them sell for about $50 or less surplus. They can't be driven directly from a DAC due to the current requirements, which if I remember correctly, I drive mine with about 5V and it draws around 125-200mA. You have to remember though, that there is a magnetic field developed around a coil of wire in the GM-20, so what ever driver you build for a GM-20 needs to be diode protected from back-EMF when that field collapses.
I think this just might be a thing left over from projectors that use ion lasers. If you loose power to the projector, the laser may still be running, plus, with a neos pcaom, the driver may be getting its power externally as well. So this leaves the door open for a situation where power dies in the projector, there is still a beam from an ion and the pcaom is still operating from the driver probably located in a rack external to the projector. So what you would have is a static beam anywhere the scanners decide to come to rest, hence the need for a spring loaded (or torsion bar) shutter. An STP-8 isn't going to do much of anything when it looses power!(Personally I think it's a dumb requirement, since on a loss of power the lasers turn off anyway!)
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buffo
Originally Posted by DZ
