Re: 9 volts is 12 volts is 8 volts etc.
- From: szekeres@xxxxxxxx (GregS)
- Date: Thu, 29 Sep 2005 18:30:33 GMT
In article <dhhaiu$e2k$1@xxxxxxxxxxxxxxxx>, kludge@xxxxxxxxx (Scott Dorsey) wrote:
>In article <1128007397.197287.256760@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
>apa <tacoma57@xxxxxxxxxxx> wrote:
>>I've always wondered, why do manufacturers label wall warts with
>>voltage ratings different than what they measure at when not under
>>load? The Boss adapters I have all show about 12 vdc. Digitech ones
>>read 9.5 vdc. Generic 9 volt one is around 8.5 vdc. 9.5 and 8.5 seem
>>within reason, but 12vdc from a 9 volt adapter?
>>
>
>Because they are using crappy transformers that have poor regulation.
>You get 12V unloaded, but you get 9V at rated load, I bet. You want
>constant voltage with varying load, you'll need to get a much higher
>grade transformer that might cost as much as a dollar or two. This is
>far more money than wall-wart manufacturers will spend.
>--scott
The label is the voltage under load. Figure a great transformer may have 10%
regulation. Getting into 15% is what most equipment has for inboard transformers.
Now with 33% regulation it gets into the so-so region. Figure these things
aer self limiting. If there is an output short, they limit, get hot, then burn out,
or just stay hot. Never believe what they say as far as DC or this and that.
DC could be half wave rectified diode, with no filter capacitor.
I have bought and used some nice switching regulated walwarts from Jameco,
and surprisingly, are very quiet, small, and deliver a load of current for
their size.
greg
.
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