Automatic reverse loop module

[RailCop]

I recently installed an Auto Reverse Loop Module on my layout and was impressed with it's operation. The module is made by MRC. However, lately it doesn't work. I initally used it with my NCE DCC system but recently I was using a regular power pack (straight DC) to run an older engine and the module failed to reverse the polarity. Do these units only work with DCC? Did I possibly burn the unit out by using the DC power? I haven't had a chance to re-connect the DCC syatem back up. (my layout is in the early stages of construction and my DCC system is not installed yet. I was just 'testing' it earlier. I used the straight DC for other 'testing' :| ). Any advice will be appreciated.

Also, if anyone has any experience with these auto reversers I would appreciate some imput. I know there are several manufacturers of these units out there and am wondering which is best.

Thanks,

Kevin