Thanks to everyone for your advice.
Gary, you are right, it does look like the circuit board itself must cut down the juice for the 3 volt LEDs. So, I think that if I can get a motion detector that takes 9 to 12 dcv to operate, and then it sends this juice down the line to the circuit board, then things will be OK.
The description says the LEDs must be "max 3 volts." And, it uses 4 bulbs.
So, I am going to buy a dedicated used dc transformer from an HO set, which I can get for about $10.00 at the flea market, and slowly increase the volts until everything works, and then just leave it at that setting.
Thanks again to all.
Mannyrock