Im looking around to find a packard shutter to modify (to use on my DIY meniscus project). Here's a quick schematic I drew up; I plan on replacing the pneumatic cylinder with an electromechanical solenoid. I still have some math to figure out, but it should work OK. 1/30th might be abit fast (1/15th might be as well...); as I haven't began to look at actuator speeds yet.
Both switches will be actuated by a typical shutter release. S1 is to be used for the 'speed' exposures, whereas S2 is a bulb/focusing switch. It isn't the best way; but my electronic engineering is quite limited.