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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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9V Plug top power supply measuring 13.5 Volts!!!
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 |
#2
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9V Plug top power supply measuring 13.5 Volts!!!
Try loading the output. It should drop the the 9 volts when loaded down.
- Tim - In article d0f8caf8-f342-4bec-adea-566521fd7558 @h2g2000yqj.googlegroups.com, says... 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 |
#3
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9V Plug top power supply measuring 13.5 Volts!!!
On Wed, 10 Feb 2010 06:44:25 -0800 (PST), Control Freq
wrote: 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? 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 |
#4
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9V Plug top power supply measuring 13.5 Volts!!!
In article
, Control Freq wrote: 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? 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 London SW To e-mail, change noise into sound. |
#5
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9V Plug top power supply measuring 13.5 Volts!!!
"Control Freq" wrote in message ... 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? 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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