I have bought the wrong Seuthe steam generators (Seuthe 12) for my model railroad because I have no too less supply voltage for them. So I developed a simple circuit switching both half waves from the rail supply to the steam generator. For now on they work very well with a voltage of 22 Volts supplied to the circuit.
Photos (some changes made, have a look at the circuit!):
http://bazaar.launch … generator_switch.png
(I used Schottky diodes because of the smaller Von, and a smaller Rv for the optocoupler)
->The standard NPN could be replaced by a NMOSFET if you need more voltage on the steam generator…