What is your PWM frequency? A schematic would also be helpful.

Hey Bill, you wouldn't happen to know of an inverter circuit that could power a fluorescent bulb (spiral) from 12v supply would you? Not a switched inverter 12-120v, but a small DIY circuit. Thx

 

Hey Bill, you wouldn't happen to know of an inverter circuit that could power a fluorescent bulb (spiral) from 12v supply would you? Not a switched inverter 12-120v, but a small DIY circuit. Thx

(added) to replace the voltage multiplier circuit the bulb comes with, sorry, didn't make that clear

 

Hey Bill, you wouldn't happen to know of an inverter circuit that could power a fluorescent bulb (spiral) from 12v supply would you? Not a switched inverter 12-120v, but a small DIY circuit. Thx

This is called "hijacking" a topic, and is frowned upon around here. It causes confusion to interject discussion that is not directed at assisting the original poster. You are much better off starting a new topic. If you've found a thread that's very similar to your question, I suggest that you include a link to that topic in your new topic.

But in an attempt to answer your question;
Basically, you'd need to remove the primary winding of the transformer, and then re-wind it with roughly 1/14 the number of turns, but in a larger gauge of magnet wire.

Then you would need to build an H-bridge circuit to drive the new primary winding, and set it up to oscillate at around 60Hz. If the original bulb was rated at 20W, you would need about 1.7A of current in the primary windings.

 

Thread from which this one was culled my be referenced here:http://forum.allaboutcircuits.com/showthread.php?t=12974

 

Off the top of my head, no. I've seen several references to a flyback voltage generators, but the Sgt. is pretty good at this stuff, so I would go with his advice first.

Personally I would buy a small 25-40W invertor, they are pretty cheap nowdays (around $15-25) and go that route. Baring that, there are plenty of small transformers that you could make an invertor out of using power transistors. The wattage is the thing though.

Just a suggestion, post your questions to everyone. I'm a regular here, so I'll be in the crowd. There are a lot of smarter folks than I, so you limit yourself if you depend on just me.