>I need an approx. 48Vac (rms) source for some quick testing.  So I 
>open
> an adjustable DC wal wart, remove the capacitor, but found the 
> maximum
> tap I could get was about 24Vac.  As it is a 240Vac line here, and 
> there
>  is an option to switch the line select to 110Vac, I gave it a try
> (actually 2 tries to burn 2 transformers).
>
> With no load, the transformer burned out few second later.  The iron 
> was
> hot, and the primary side seemed to be burned out as it was measured
> open.  I could not cut through the paper to see what had burnt last
> night as they were hot, but they are gone now (thrown off).

Given two supplies you could have run both and placed their 
secondaries in series.

Failing that a little magic and playing with some L's and C's would 
possibly give you what you wanted.

If you had anything else with a 2:1 winding ratio and a lower winding 
voltage >= about 20VAC you could have used that as a 2:1 stepup 
transformer.

Excessive voltage will increase the nmagentisation current which will 
saturate the core which will drop the primary inductance which will 
... :-(.



    Russell 

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