Guys,
I need to control an external magnet, but this isn't the standard relay control.
I have a section of track known as a 'point' (railroad terminology) that changes the path that trains take. This is controlled by two small electromagnets. There are two (one to pull in each direction, whilst the other pushes) and they are wired in series. You can see pictures of them here. The direction is controlled by the DC polarity.
Now, I don't know exactly how much current these draw (I intend on checking tonight) but I do know they can function on lower voltages (9v tested successfully)
My question is, how do I control a DC supply momentarily and be able to reverse the polarity? Every schematic I have seen just shows the typical NPN transistor with diode and relay in a fixed polarity.
I suppose I would like to only have one pin of my Arduino used to control one 'point' and, if possible, make it toggle when the pin is momentarily set high. I understand this would then need a flip-flop gate, and am happy to sort that out... the issue then still is to work out how to reverse the polarity and have the power to the point motor/magnets still isolated.
Thanks in advance for any advice.