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testing a PSU output under load?

Started by LaceSensor, September 28, 2014, 09:24:09 PM

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LaceSensor

Hi

I have a 12v AC output on my power supply unit, and want to test how it is under load
Reason being I want to power my TZF from it, which is rated for a 9v AC supply.
Im told by Dave Fox that if its really 12v under load, it will be ok, as most (unregulated) AC/AC wall warts put out 11v approx.
If its much higher though, apparently it might overheat the regulator(s) inside the TZF = not good

Ive tested with a DMM just the electrodes connected to a cable from the power supply and get a steady 12.2-12.3v AC
I assume under load would be lower than this, but I dont know how to test it "under load" other than to connect to a pedal that wants 12v AC...and I dont actually own any!

How can I simulate "load" and test this properly. I dont want to fry my TZF (although Im sure I could fix it) for the sake of 1 more wallwart...

thanks!

Ian

alanp

Power resistor of some sort is the most obvious route. You can get some really, really chunky ones suitable for 50W amplifiers, so the kind of load a pedal uses should be a doddle.
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LaceSensor

High you might have to spell it out for me? Like put a resistor across the terminals then test the voltage?

nzCdog

What is the current requirement of your device, Lace? What does the manual say? If you know that we can do some maths :)

peterc

What is the rating of the PSU? Does it say 12v @ 500mA or 12v 10w, something like that?

If there is a rating, its easy to determine the max current it will output and determine a test current for 'under load' conditions.

Peter
Affiliation: bizzaraudio.com

LaceSensor

It was for the paradox TZF but Ive decided to play it safe and run it off a line 6 9vAC supply.
Dave Fox is such a legend though he told me even if I fried it he would fix it for free haha
I could probably fix it myself but its great customer service (especially as Ive never paid him a penny)