> >>... In my 30+ years of designing products, I've NEVER seen 
> a wallwart 
> >>that delivered  less than 7V (I'm sure they are there, but 
> I've never 
> >>seen  any.
> 
> > They exist, and they're becoming more common.  I've got a 
> few odd-ball 
> > wall warts, 2.5v, 3v, 4.5v that power dictaphones, 
> walkmans, portable 
> > CD players etc, mainly stuff that used 2xAA batteries.  Low amps, 
> > these usually didn't recharge the device.
> 
> As a general but reasonably adhered to rule, unregulated 
> supplies will have outputs up to around 40% above rated 
> voltage on light loads and regulated supplies will have 
> voltages about as specified. "Regulated" 
>
>
>
> voltage variation and cost an SCR preregulator was sometimes 
> used, and a FET based system would nowadays be about as 
> cheap. But it is most unlikely that you would want to use 
> such a system.
> 
> A simple and cheapish and moderately effective system would 
> be the use of a simple series preregulator using a zener and, 
> a pass transistor and another control transistor plus a very 
> few glue parts. This can be cheap and reasonably effective.


Nah, "Warranty void if non-approved power supply used" sticker - how much
are they?  :-)

Tony

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