Elmo K-100 SM - adjusting frame rate to 1 fps

[carllooper]

I've got an Elmo K-100 SM Super8 projector which I was using as part of a telecine system.

I modified it last year, replacing the motor with a stepper motor, for projecting at really slow rates (eg. 1 frame per 20 sec), and replaced the lamp with an LED light (so as not to melt the film). The reason for doing this is that my digital camera has a maximum capture rate of 3 fps, when capturing at 4K.

However the stepper motor was a little unreliable. It didn't quite have enough power to always advance the film. Occasionally it would get stuck, trying to advance the film but failing. I was going to get a higher power stepper motor when priorities took a different turn. A friend needed a Super8 projector for something he was doing and I restored the projector back to it's original spec. And quite proud of doing that since mechanics has definitely not been my thing.

Now at original spec the projector runs at 14 - 24 fps, with a slow motion switch which changes it to 5 - 8 fps. In slow motion mode it puts a grill in front of the lamp to cut down the light (so as not to melt the film).

But now I want to have another go at modifying the projector for use in a telecine (or "datacine") system. But rather than try the stepper motor idea I was wondering if anyone knows how to modify the projectors motor so it's frame rate was something like 1 or 2 fps. I'm a bit rusty on electrical theory but can certainly follow it, if anyone wants to have a go at explaining how one might mod the motor, or what the obstacles would be against doing so.

Carl

ps. almost answering my own question (as so often happens) I found any given motor has what is called a "stalling torque" so it's a question of whether the projector motor, even when modded, might stall (not rotate at all) when attempting to achieve a rate lower than it was otherwise designed to do. http://lancet.mit.edu/motors/motors3.html#tscurve