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Amp ratings of power adapters

T

Thomas G. Marshall

Jan 1, 1970
0
Hugely fundamentally ignorant question.

If I have an electronics device that claims to take a power adapter of 12V
200mA, and I plug in one rated at 12V 800mA, will the device merely draw the
proper 200mA (because the voltages are matched)?

Or is there something about PA's that can somehow force too much current
into a device?
 
J

Jamie

Jan 1, 1970
0
Thomas said:
Hugely fundamentally ignorant question.

If I have an electronics device that claims to take a power adapter of 12V
200mA, and I plug in one rated at 12V 800mA, will the device merely draw the
proper 200mA (because the voltages are matched)?

Or is there something about PA's that can somehow force too much current
into a device?
The rating on the supply indicates what it can deliver to the device in
terms of current. All this means is a connected device requesting
current can not ask for any more than 800 ma.
The device connected governs how much current will flow, the supply
only indicates the amount it can give with out damage or shut down to
it self.

Voltage of the supply must be close or exact to what the device requires.
In your case you have a 600 ma reserve or power, so you are fine..
 
E

Eeyore

Jan 1, 1970
0
Thomas G. Marshall said:
Hugely fundamentally ignorant question.

If I have an electronics device that claims to take a power adapter of 12V
200mA, and I plug in one rated at 12V 800mA, will the device merely draw the
proper 200mA (because the voltages are matched)?

Basically that's the idea.

Or is there something about PA's that can somehow force too much current
into a device?

See other posters' warnings about unregulated adaptors having a higher voltage
when only partially loaded.

Graham
 
P

PeterD

Jan 1, 1970
0
Hugely fundamentally ignorant question.

If I have an electronics device that claims to take a power adapter of 12V
200mA, and I plug in one rated at 12V 800mA, will the device merely draw the
proper 200mA (because the voltages are matched)?

Or is there something about PA's that can somehow force too much current
into a device?

It may work, and it may not... Some crappy designs deliver the rated
voltage only at (or near) the rated current, and as current drops,
output voltage rises. As such a lightly loaded unit may in fact cause
damage because of overvoltage.

Realize that these cheap wall warts are *not* regulated, and the
output voltage is approxmate at best in most cases.
 
X

XTL

Jan 1, 1970
0
Hugely fundamentally ignorant question.
A very frequently asked one, as well. And very frequently answered.
Others gave real answers. I agree with the correct ones ;)
If I have an electronics device that claims to take a power adapter of 12V
200mA, and I plug in one rated at 12V 800mA, will the device merely draw the
proper 200mA (because the voltages are matched)?

Or is there something about PA's that can somehow force too much current
into a device?

Actually, I believe. One kind of adapter that might be able to put
more current into a device (by raising the voltage, of course) than is
"asked for" is a constant current supply (battery charger for variable
number of cells). But it's very unlikely that you have one. The plate
would probably have to be wrong, too.
 
J

Jakthehammer

Jan 1, 1970
0
Thomas G. Marshall said:
Hugely fundamentally ignorant question.

If I have an electronics device that claims to take a power adapter of
12V
200mA, and I plug in one rated at 12V 800mA, will the device merely draw
the
proper 200mA (because the voltages are matched)?

Or is there something about PA's that can somehow force too much current
into a device?


Yes IF the power are really what the label said.

How do you know the powers are matched? Not all adapters telling your the
truth. Use a meter, do not trust the cheap wall-adapters made by the
Chinese.

Jack...
 
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