I'm trying to control multiple solenoids (home made) using a shift register controlled by an Arduino. Ideally I want to be able to direct them all together either inwards or outward using the current direction.
I had originally looked at using an H-Bridge, but I have about 200 solenoids to control so it was going to become too expensive. I figured I might be able to switch the direction of the current and send 2 sets of values to the shift register, using the first bit to specify the direction. By daisy-chaining 25 shift registers I can control all 200 (well 199 - but that would be enough).
Something like this:
- Bit 0 - connected to mosfet that controls relay that sets the current direction
- Bit 1 - connected to mosfet that switches solenoid 1 either on or off
- Bit 2 - connected to mosfet that switches solenoid 2 either on or off
- etc etc
Datasheets are as follows:
I've attached a diagram, I've omitted the connections to the arduino for simplicity but I do have a few questions.
- Does this look like it will work? Am I totally off the mark?
- Do 2n7000 mosfets allow current in reverse?
- Would it be better to have 2 mosfets for each solenoid and keep everything separate?
- If yes to 3 - do I need diodes in front of them or how do I go about protecting them from backflow?
- What would be the best way to arrange the snubber diodes? (assuming that they are needed)
Thanks in advance for any help!