Again Joe,
My understanding of what Mike has now stated, is that short repetitive pulses of say 250 ms, will not cause a kick down, whereas a longer pulse or pulses will. On this basis, continuous pulses not exceeding say 250 ms, will result only in constant power mode, which is what is desired .
A 555 timer IC could be used but a simple two transistor multi vibrator flasher type circuit would suffice. The best way to go would be to check hobby shop kitsets for something suitable, as this would take a lot of the hassle out of assembly and would be cost effective.
Edit P.S. I have had a quick look at a catalogue covering hobby electronics and a 555 timer kit which can be used to build all sorts of stuff is available here at NZ$30.00. A flasher kitset using discrete components, NZ$8.00
You may have to incorporate a driver transistor, depending on the current requirements. An IC regulator rather than a simple voltage divider would not go amiss. I hope you have the time to play, as have no desire to get involved.
Again Cheers, Trevor.