I'm looking to replace a damaged 12V 1A DC power adapter for a piece of
computer equipment. I have one similar with correct plugs etc but its 12V
1.5A DC (came from another piece of equipment). Is this safe to use as a
replacement - i.e the current output of new one is higher than old one, does
thank you both for your help.
How do I check the polarity of the connector and whether its regulated or
Both are black power-brick type adapters. Original was from a Belkin switch
and my proposed replacement is from a network camera, so they are for
Have a look on the power supply it should show the input and output ie 240v
in 12v out and a little sign indicating a line and another line with a semi
circle&line informing you of its polarity +&-
Most power supplys are regulated nowadays so dont worry too much because if
its not stated on the outside of the supply you will need a meter or opening
the PS to detect what it is.
For polarity look at the label on the adapter, which normally has a
small diagram showing the inner connector (+) and the outer connector
(-), or (rarely IME) the other way round. If the adapters aren't
labelled, the boxes you plug them into surely will be. Almost all
adapters are regulated these days.
Have you checked (with the power off, of course) that the plug actually
fits? Lots of them look the same size but aren't. Just a fraction of a
mm is enough to cause problems, the plug either won't go in or goes in
I assume they both have similar cylindrical output connectors? There's
usually a diagram on the body of the supply showing whether the inside is
+ve and the outside -ve, or vice versa. Otherwise, you need a DC voltmeter.
I'm sure I've read somewhere that devices requiring a regulated power supply
have a fatter central pin in their connector, and the power supply plug, a
larger hole - preventing an unregulated supply from being used. I'm not sure
whether that's universal.
An unregulated supply will have an open circuit voltage considerably above
the nominal output voltage, and will relay on the load of the powered device
to bring the voltage down. If used with something which only draws a very
low current, some damage could occur.
Make sure the polarity of the two plugs are the same plus check both
are regulated and there should not be a problem. Regulated means the
output is regulated at a fairly accurate 12v within a wide load range.
It might say 'regulated' on the case - if not you can check it with a
volt meter, no load output should be quite close to 12v.
It *might* matter if the normal average load on the original is low and
regulated, and the more powerful one unregulated. For example a printer
might have a very low power consumption when not actually printing and a
large unregulated supply might produce a high enough voltage to damage it.
But it's not that likely. If the larger one is regulated you should be ok.
*El nino made me do it
Dave Plowman email@example.com London SW
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