Just rewind the output for lower voltage/higher current
12v to 3v is only 1/4 so four windings paralleled, 1/4 of the number of
existing turns 
( most units I've opened have around 12 turns on the output, no feedback
from the output)
A 150 watt unit's output would be 12.5 Amps anyway.
Rewound 4 X 1/4 would be 50 amps. 
Plastic case, galvanic isolation.
Standard dimmer on the input for output voltage control.
Seems like it would meet all the requirements.
The soft start could be a problem or an advantage though 
Defiantly worth playing with!

 PC

> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu] On Behalf Of Peter L. Peres
> Sent: Saturday, January 29, 2005 9:41 PM
> To: Microcontroller discussion list - Public.
> Subject: RE: [EE] Single Phase AC control via PWM (maybe a challenge?)
> 
> 
> 
> 
> On Sat, 29 Jan 2005, p.cousens wrote:
> 
> > If I had to do this I'd hack a dimmable electronic l2v halogen 
> > lighting transformer Give me $3,000 I'll supply you 10 :-)
> 
> I'd charge a little more having been down that avenue (hint: the 
> dimmables I have in mind are *too* cheap for hacking - it's 
> the case of 
> not being able to remove or modify any parts without their 
> blowing up - 
> maybe a more expensive model ...)
> 
> Peter
> -- 
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