DIY advice...

[Joost Schuttelaar]

On May 8, 2011, at 20:45 , Tony Scharf wrote:

> What worries me about this particularly PSU is that the output amps
> are much higher than I need, and are order of magnitude higher than
> what I have now.  Is that dangerous?  I have been under the impression
> (perhaps incorrectly) that so long as the voltage rating is correct,
> the amp just need to be at or above whatever your trying to power (so
> a device that needs 12v/1000mA will run fine if you plug 12v/1500mA
> into it, but not at 9v, 15v or 500mA).  Is that correct?

Yep! What the mA of an PSU means is that it can deliver that amount of current for a sustained duration of time (at the specified voltage). Current * voltage = power. So a feeble PSU can for instance deliver 200mA at 12 volts (2.4 watts), whereas a bigger one can deliver 1000mA at 12 volts (12 watt).

If you try to draw more current than it can deliver the PSU might for instance overheat, or certain components will fry, or it will trip a fuse... basically you're then driving the PSU harder than it can handle.

Same as Tom write, I also try to stay within a very safe range of those mA with the stuff I use (LED-lights) :) because I don't trust that these crazy cheap made-in-china PSU's will actually last when they are driven to their specified max :)

BTW: Others on the -bar are more qualified than me to elaborate :)

-- 

Joost Schuttelaar
The Hague, NL