Good info again guys thanks. That RYO heat sink is pretty neat. 
So actually the smoke unit in question operates just fine; it's a NOS spare one I had in the parts box. But I want to modify it for a friend who runs RC boats. One of the boats is steam powered (simulated), and he figures a smoking stack would be a nice touch. The problem is the boat is powered by a standard 8 VDC high amperage battery , like those used in modern RC aircraft. So instead of 12 VAC track power, we have 8VDC battery power to work with. Of course the smoke output is anemic on 8 VDC.
So looking at my markup below, I figured to jumper the bridge diode as shown, and cutout C1, not needed. The 5 V reg circuit can stay intact to power the fan. I would also remove zener diode D2, resistor R2, and transistors Q1 & Q2, whatever all those components do. Then I would jumper the center point of the two 16 ohm heaters to hot as shown, and cut the trace powering the top of R1, and jumper it to ground of R3, which on the PCB is right next to it. Fairly straightforward.
When this is all said and done I should have an effective resistance across R1-R3 of about 8 ohm, which should draw about an amp on 8 Volts, and use about 8 watts of power. From my experience this should produce a pretty good volume of smoke. So I just wonder if you guys think my logic is OK, and whether this will work as intended? 
Rod
