Non Switching 220v Power Supply, Used with 110v, how much does current decrease?

Dec 31, 2005 2 Replies

I was sent a power supply for a unit that requires 9 volts DC with



180ma. The power supply says input 220v AC, not 110-220v, so I guess that means non switching, and is supposed to supply 300ma of current. . I

checked the voltage output and it is 9.5 volts, so I'm good with that, but I do not have an amprobe, so I couldn't check the current. Basically the power supply does not have enough "juice" to power the unit (a CCTV camera).



Here is the question. Since I can't check the amperage from the power supply, could the fact that I'm pluging it into 110v and not 220v



be the reason that I am having a problem? What would the amperage output of the unit be? Is there a conversion formula? Is it half? It appears to be the situation. Thanks in advance.



Your power supply wasn't designed to run off 110v. Either plug it into a

220v socket, use a 110220v autotransformer and plug it into that, or buy a 110v power supply replacement.

Your unit sounds as if it is a non-switch mode power supply intended for

220v AC. When on load and supplied by 220v, it will have an output voltage of around 9 v dc. Off load, it will be significantly higher.

When you power it will 110v, you have found that it does give 9.5v dc out - off-load. As soon as you put a load on, however, the voltage falls to too low a value to power the camera.

Catalog # DCTX-936 from Allelectronics provides 9 V dc at 300 ma. Put one 82 ohm resistor - catalog # 82-5 - across the output, and you have a suitable supply.

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Ed

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