Circuit design question

[CTho9305]

I'm thinking of a setup kinda like this (AC power source, load - an electromagnet, "stuff", ground). At any point, only one of the two loads should have current flowing (and thus be magnetized). Would something like this work? How would I use its output to achieve the desired result? Am I looking at this the wrong way entirely?

The end result should be a simple linear motor - so I need some parts of the "track" to be active and others not

 

[Mark R]

That type of circuit should work fine if you add an inverter to the output (essentially giving you Q and -Q), but you are limited only to 2 circuits. 555 is nice and cheap and simple, and a 7406 is also cheap and simple.

If you need more than 2 seperate circuits, then I would suggest a binary counter, and multiplexor.

If you could use DC to drive the coils then you could use simple and cheap NPN power transistors or N-channel MOSFETs - though both need adequate clamping diodes to protect them from the back emf.

If you are using AC to drive the coils, then for the switches I would use solid state relays, easily built from a triac triggered by an opto-coupled triac (this will easily handle 240 V mains, depending on the quality of your construction) and an appropriate RC snubber. However, triacs have the complication that they don't automatically stop conducting - the current has to stop for another reason (with AC this happens at the end of a half-cycle, 120 times every second), but this would mean that for short periods both circuits could be energised.

Conventional relays could be used in either case as long as they are fast enough - in either case, you will probably need to use a transistor to drive them as the 7406 is unlikely to manage.

 

[blahblah99]

I'm not quite seeing the big picture of what your trying to do. are you trying to make a circuit to allow your motor to flow in forward and reverse motion? If so, you can pick up h-bridge ic's that'll do that function for you. You just give it a 0 or a 1 to flow forward or reverse, plus a 0 or 1 to stop, or go.

If you just want to switch that on and off so only one path is on at a given time, you can use low-on resistance n-channel fets and drive the gate with 0/1 to turn it off/on. Or a simpler way would be to use relays, but make sure your source can drive the coils of the relay.