Are there things I haven't thought of here
Are we talking 10 turns, 100, 500?
If I connect 200 enable pins to a single Arduino output pin like that, would that require a transistor?
I found that a H-Bridge Motor Driver like L293D or SN754410 (https://www.sparkfun.com/products/315) could be used to reverse polarity. Those could in fact control two solenoids each. And if I understand it correctly, I wouldn't have to use any other transistor to do the current switching either. Am I wrong here? Is this IC unsuitable for any other reason?
It's DC, so a coil is pretty much a short circuit, right?
Should there be a resistor involved
The H-bridges mentioned are for 1A max, but there might be sturdier ones.
Your power supply requirements.
Depends on the physical force but normally over 1000 turns.
Yes, in fact several [transistors]. You could use 74LS04 buffers and drive 20 shift registers with each one. There are six in a package.
No wire, especially thin wire, has a significant resistance when you have 1000 turns.
I don't think you need 200 drivers. It doesn't sound as if you will need to power multiple solenoids solenoids simultaneously so you could multiplex then in a matrix. A 14x15 matrix would be enough to support 200 outputs.
Have you considered a simple lever @ 1/4 amp/solenoid is 50A total
The lever concept and semaphores (as hinged flags) might simplify what appears to be a mechanically challenging task.
What about using servos ? They could be a little more expensive, but they are in the same price range. 200 servos at 5V with a computer power supply could be done.
The Arduino Mega can control up to 48 servos. So a few Arduino Megas is all you need.
The metal moving core in a solenoid is not a magnet, so reversing the polarity won't change anything. The metal core will move in the same direction.
Oh, interesting! I looked at a couple of examples of multiplexing for LED matrixes. But are you suggesting putting a motor driver before the multiplexing bit and then multiplex that driving current coming out of it? Seems like it would require some very sturdy shift registers for sourcing/sinking current? Also, do you think alternating between energizing all these different solenoids very fast would energize them enough to pull the plungers?
I took an iron nail about 70mm long, put it in a thin plastic tube cut about the same length, then wound copper wire, about 1.2mm thick, just 20 turns around the tube from end to end. When I pulled the nail out a bit and connected the wires to a 1.5V battery, the nail was sucked back into the tube no problem. I could pull it out as far as two thirds of its length and it would still go back in in about a second. Not much force to spare I'm sure, but I don't need much more than that for my purposes. The wire and battery got hot quite fast if I kept them connected of course, but they would only energize for less than a second at a time with plenty of time to cool off between times.