Hi,
Is this normal? I have a plug top power supply, for UK. The sticker shows: AC/DC Adaptor Input 230V ~ 50Hz 11.2W Output 9v 500mA 4.5VA
I have just measured the voltage at 13.5 volts (DC).
I guess I have bought a non-standard item!!
Anyone else experience this sort of thing before?
Regards
Try loading the output. It should drop the the 9 volts when loaded down.
- Tim -
For devices that have their own internal regulation and that don't need a tightly regulated supply (e.g., one that can run from a battery), this kind of supply is simple and cheap. Think of it as a 13.5 VDC "pure" supply in series with a source impedance of about 9 ohms. When it is supplying a 500 mA load, that internal resistance will drop about 4.5 V, so at the terminals you'll see the expected 9 VDC.
-- Rich Webb Norfolk, VA
Pretty well every power supply will read high if measured with no load. Even a regulated type has a small internal parasitic load to allow the regulator to work correctly.
What you've observed is perfectly normal for a basic non-regulated supply. With a load drawing the quoted 500mA it should drop to 9 volts. Or thereabouts.
--
*Can atheists get insurance for acts of God? *
Dave Plowman dave@davenoise.co.uk London SW
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That's normal. Note the rating is for 500 milliamps. Put a 500 mA load on the output and you will see 9 volts.
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