Two DPDT switches with timing for one motor Answered
I have a motor (12V DC) that I need to be able to operate both backwards and forwards from two locations. The simple way is to connect it with two DPDT switches with momentary on in each end and off in the middle, i.e. also called (on)-off-(on). The reason for using momentary switches is that there would otherwise be a risk of short circuiting if one of the switches are left in on-position. However, I almost always need the motor to go to preset limits in both directions which takes a couple of minutes (the limits are built-in functions in the motor, so no need to set those). So I was wondering if there was a cheap and easy way of inserting a kind of timer or similar that would only leave the connection on for a couple of minutes only (and yes, there would still be a risk of short circuiting within those two minutes, but it would be unlikely to happen)?
Or perhaps there is an even simpler way of doing it?
Any ideas would be welcome. In (the likely) case the above is not clear, perhaps this will help: I need it to operate a curtain, i.e. moving the curtain up and down, but I need to be able to do that from two different locations. Preferably it would be good if I could also stop the engine somewhere in the middle - as I would be able to do with a switch simply be releasing it. The best/cheapest/easiest way would, I think, be to have two DPDT switches with a spring or something with a couple of minutes delay, i.e. if it is left in the on-position for more than two minutes it would automatically spring back. But such a thing seems not to exist... or?
Would be grateful for any inputs.