[sdiy] Load testing dual PSU

[Laurie Biddulph]

Hi,

I would have thought a handful of 120R resistors in parallel would be 
more useful. 120R should give you 100mA so just add multiple (10 for 1A 
and 30 for 3A). That gives you 100mA increments.

When testing my supplies I did not see the benefit of such fine 
resolution so went for some 12R resistors and 120R allowing me to do 1A 
and then a bit, 2A and a bit and finally 3A. I used 25W power resistors 
and threw a fan in to keep them comfortable

Best Regards
Laurie Biddulph
Mobile: 0400 257 645
Phone: +61 (0)2 4340 0938
Web: www.elby-designs.com
Skype: widgetoz

Elby Designs
9 Follan Close
Kariong
NSW 2250
Australia


On 4/11/2014 2:28 AM, blacet at blacet.com wrote:
> A few calculations with Ohms law will do the trick. R=EI
>
> W=EI will give you the minimum resistor wattage. I tend to use cheap ones
> from Mouser in the white ceramic housings. I also use 2X the minimum power
> to avoid them getting really hot.
>
> I will string a few of them together as required to get the necessary ohms
> and watts.
>
>
>
>> Hi Roman,
>>
>> Thanks for the confirmation. In fairness I probably just need to get some
>> higher power resistors. For some reason I had it in my head that they
>> would be hugely expensive. I think I was picturing massive heavy ones that
>> I remember from college. I'm sure they aren't as expensive as I thought.
>>
>> P.S. Friend request sent. I'd like to see the photos of that's okay.
>>
>> Cheers
>>
>> Rob
>>
>>> On 3 Nov 2014, at 12:49, Roman Sowa <modular at go2.pl> wrote:
>>>
>>> hi,
>>> actually I use both :)
>>> A string of 1 ohm 20W resistors, about 15 of them, so I can adjust load
>>> resistance with banana cable by clamping part of the string. And there
>>> is also G4 socket with soldered across part of the ladder, so I can see
>>> if there's heavy current flowing or not witout looking at power supply
>>> Amp meter. This is usable when testing switching circuits. I plug there
>>> 5W, 10W or 20W bulb depending on needed load capacity.
>>>
>>> It get's hot, no matter what you do, just learn to live with that. Not
>>> really pssssst hot, the resistors get nicely warm/hot after some time at
>>> 3A.
>>>
>>> Your temperatures will stabilize in manner of minutes, not days, so
>>> unless you are doing burn-in test, there's no need to leave it on for so
>>> long.
>>>
>>> Roman
>>>
>>> PS for my Facebook friends, few hours ago I posted a picture with the
>>> load fixture described here.
>>>
>>>
>>>
>>> W dniu 2014-11-03 13:24, Rob Spencer pisze:
>>>> Hi,
>>>>
>>>> I've recently developed a +-12v PSU, with +5v and post voltage
>>>> protection and am looking to do some load testing. I know I could
>>>> stick a low resistance across it but that's going to get very hot
>>>> very quickly. The other thing I'm thinking is to place some 12v light
>>>> bulbs across the rails and leave it running for a few days with
>>>> temperature monitoring in place on the voltage regulators.
>>>>
>>>> I'm wondering how other people have tackled this in the past.
>>>>
>>>> Cheers
>>>>
>>>> Rob _______________________________________________ Synth-diy mailing
>>>> list Synth-diy at dropmix.xs4all.nl
>>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
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