Implementation Question - Can I safely wire an additional Arduino circuit to the magnet, in reverse polarity, by using diodes to prevent the magnet's external power supply from traveling up that "reverse circuit" and shorting out my Arduino when the magnet is turned "on" ?
During the operation of the electromagnet there is current going through the coil. When the power is removed via the relay, is there a path for the leftover current to go through or will it just stay in the coil?
Yes Thanks !DVDdoug seems to have grasp my project exactly. Sorry for the initial, poor description.While my Graphics Foo is not very good, I have drawn a VERY simplified version of the existing circuit and have attempted to attach it to this post.
Diodes will NOT work. The back-EMF from an inductor can be thousands of volts and it can fry the diode if you put the diode in series.
I understand that there is something called an "H Bridge" that allows you to reverse polarity on a motor, to run it in reverse. However, I don't need to "run" anything for any length of time. I just need a single, split second of power and a very small voltage at that. In a test (isolated from the Arduino) I have made the magnet release with a 3 volt spike but I suspect I can use even less than that. Also - the H Bridge seems complicated and perhaps expensive.
I did notice that only .7v came through the diodes but that was enough to instantly release the magnetised plate.