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lourk



Joined: 12 Nov 2007
Posts: 1

PostPosted: Mon Nov 12, 2007 7:03 am    Post subject: Power Supply Reply with quote

Hello All,

I am a newbie on this forum.

I have a Vtech cordless phone and the power supply was damaged so I want to buy a universal power supply to replace the broken one. The Vtech Power supply specs are:

Input: AC117V 60Hz 6.5W
Output: DC9V 150mA

Is it okay to replace it by a universal power supply that the specs are:

Input: AC220V 60Hz
Output: DC9V 500mA

?

Your help is highly appreaciated.

Thanks
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torbjorn



Joined: 07 Jun 2007
Posts: 370
Location: Sweden

PostPosted: Mon Nov 12, 2007 1:00 pm    Post subject: Reply with quote

Some wall adapters (in particular, short-circuit proof ones), deliver a much higher than rated voltage at light loads. In some cases, more than double the rated voltage.
When contemplating using an adapter with higher rated current than the original one, you should measure the output voltage at no load and make sure that it does not exceed the rating by more than, say, 20 % at nominal mains voltage.

For cordless telephones and other telephone equipment, don't use a switch-mode adapter as they often cause mains hum on the telephone line due to capacitive coupling to the electrical mains.
It is better with a traditional, "linear" adapter consisting of just a transformer, a bridge rectifier and possibly a voltage regulator.
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Mon Nov 12, 2007 3:44 pm    Post subject: Reply with quote

The output should not be higher in terms of DC and equal or greater in terms of AMPS. However, the primary MUST be the same. You can not use a 220VAC input in place of a 117VAC input (unless you plan on using it in Europe?)

On the secondary side, 500MA is more than enough, but should be ok.

(Btw, no connection w/Vtech brand.)
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PostPosted: Mon Dec 03, 2007 5:53 pm    Post subject: Reply with quote

let me help you go to goodwill industry and buy any transformers $2 that say 9vdc at higher amps then 150ma that will work. unfortunately some supplies connector center is positive some negative and there is the missmatch. your 220v ac input will never work on a 120 and viceversa so make sure the input matches you ac line.
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