Transfo voltage issue?

Hi all,
Excuse me but this is probably a so noob question but I dont understand that:
I have four 9V transfo at home, about 600 to 750 ma. Its different brands each
a they fit perfectly with my Shrutis an Anushri…but!
Yesterday I decided to test my transfo alone with my multimeter and I was surprised,
I found that they seems to deliverate between 14 and 15 DCvolts.
Can someone explain that to me?

Thanks

The AC->DC adapters you are looking at are unregulated. This means that they contain a transformer, a bridge rectifier, and a smoothing capacitor ; but no regulator. The output of such adapter is not a pure DC signal. Instead, it is made of peaks and valleys; and the more current you draw, the deeper the valleys are. For example, if you draw only a few mA, the valleys won’t be deep and the voltage will be around, for example 14V. If you draw more current, the filtering capacitor won’t be able to handle it and the valleys will go lower and lower, eventually crossing 9V.

So the 9V really mean - “it is guaranteed that the output voltage will exceed 9V as long as you don’t draw more than 650mA”.

So theres no problems to use these with my Shruti and anushri??

Not ideal, but not a deal breaker as long as they are not above 9 volts I guess.

thanks pichenettes and Varthdader,
but I think its time to find a regulate on :slight_smile: