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Subject: Re: Too high an mA rating CAN mean too high a voltage!!!
From: Glenn Ervin at Home (GlennErvin_at_cableone.net)
Date: 2004-03-18


I think that the way to describe this is that the voltage and the amperage
are inversely proportional to each other for a given supply of energy.

----- Original Message -----
From: "Fred Maxwell" <rockbox_at_anti-spam.org>
To: "Rockbox development" <rockbox_at_cool.haxx.se>
Sent: Tuesday, March 16, 2004 5:29 PM
Subject: Too high an mA rating CAN mean too high a voltage!!!

BlueChip wrote:

> At 21:47 16/03/04, you wrote:
>
>> I used the standard 9V Voltage. The Adapter is capable of 800mA, but the
>> Archos only need 500mA - could this be a problem?
>
>
> No, that problem is the other way around ...if the player needs more
> current than the adaptor can supply, then the adaptor will melt ...The
> adaptor will only kill the player if the voltage is too high.

I feel like I've beaten this point to death, but I don't want an
unanswered post to result in someone blowing up their Archos (or any
other piece of valuable electronics).

The 9v, 600mA wall wart that came with my Archos measures 14.5v with
nothing attached to it. That's about 61% above the rated 9v at 600mA.
If I had a 600mA load attached to it, I bet that it would be close to 9v
  out. The voltage and amperage are related in unregulated power
supplies. When you increase the load, you decrease the voltage. If you
buy a 9v at 1000mA adapter to feed your Archos, you are almost
guaranteed to be feeding it far more than 9v.

Regards,
   Fred Maxwell

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