Rod, AC volts would be higher, the full bridge rectifier drops about 1.4 volt turning the AC to DC. 2 diodes worth. The smoke unit runs on the rectified DC.
You also have to remember the QSI/PS-1 boards have several diodes in series turning AC to DC for the motors. So track voltage is higher than DC volts applied to the motor by 3 to 4 volts.
I agree though, my PS-1 engines move pretty well at 10V. 14-16 volts and they are screaming.
I traced an actual smoke unit circuit and the diagram is correct. The larger Q is a PNP, I could not find a reference on the other one, but I think it is a PNP also. What got me was looking how the resistor was in series effectively cutting current in half.
I charted the current and Watts at 2V increments. You get low resistance at low volts which is good for smoke output, but as volts get higher and you kick in the 2nd resistor the current drops in half. You make the power up as voltage increase. I am sure this helps with the resistor longevity. These are such good smoker they don't need to be messed with, but if you lowered that second resistor to about a 8 ohm, it would really be cooking.
I am going to run a test with one of my engines and run up the voltage in neutral slowly and see if I can see any difference at the cut over threshold. G
