> > - an unloaded small 9V transformer can give much more than 
> 9V (measure 
> > or find the specs), calculate with at least 12V, maybe even 18V
> 
> Using my Fluke 179 (RMS-DMM), it said 9.6VAC for the unloaded 
> transformer (no bridge).

OK. Now try a gain with a representative load.

> Measuring over "+" and "-" on the 
> bridge, it said 9.5VDC. Adding a load (100k) over the bridge 
> yielded no change for the voltage (9.5VDC still).

measuring DC without a filter cap makes nos ense.

> Could it be the transformer is marked with its effective 
> voltage? Else I should have seen sqrt(2)*9 on my DMM, no?

with a cap, yes.

Wouter van Ooijen

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Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: www.voti.nl/hvu
 
 

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