I don't think the aux jack supplies any voltage.
It's a momentary type switch/relay on the older FP's and some of the newer models can be momentary or latched depending on what the user selects.
A mojo can be modified fairly easily to be used with the newer models with latched capabilities without to much work involved.
It can be made to work with the older models also, but you need to hold the aux button down the entire time you want the decoy to operate. Not very handy and there is some concern it is not good for the aux circuit in the caller.
