Ricardus said:I don't exactly follow the explanation. The polarity relay comes after the output of the 1646. The default position of the relay is unenergized, and the output of the positive pin goes to pin 2 of the edge connector in that state.
I'm not looking at my card at the moment, but if you look at the top of the relay in the comment I just included, the + / - supply is reversed compared with the pdf.
I'm going to try and explain this again, as my original line wasn't very clear (I'm doing this for myself mainly!).
This is a non-latching relay, right?
It's basically an electro-magnet that flips a switch, but that magnet is only going to flip the switch as documented, if you're sending the current through the wire in the direction it expects.
If you accidentally wire up your circuit with the current going the wrong way, it's going to do the opposite thing.
I think that's what happened when the footprint was mirrored, and that's why the work-around was needed?
(again, just guessing here based on the original comments).