5614 Posted April 5, 2005 Share Posted April 5, 2005 PSU = power supply unit I understand that resistance in wires causes heat, I can understand how a processor generates soo much heat, I can understand that a PSU produces quite a bit of heat... What I don't get is that no matter what I do the PSU fans always belt out warm air! I mean, what the heck is going on in there that produces sooooo much heat? Link to comment Share on other sites More sharing options...
Dave Posted April 5, 2005 Share Posted April 5, 2005 The transformer gets quite hot inside. That's constantly giving out heat all of the time, plus all the larger capacitors and things like that. If you take one apart, you'll see why Link to comment Share on other sites More sharing options...
5614 Posted April 5, 2005 Author Share Posted April 5, 2005 I've got one apart on my floor!!!! Except for the high voltage caps, I took those out and put them in my electronics box thingy!!! Sure transformers and I suppose the high current going through high voltage caps would produce heat, but I am amazed at quite how much there is... normally transformers do not get that hot, I can't imagine the two 240V caps to produce enough heat to match the amount coming outta the PSU! Although I suppose logically they are the main two candidates? Link to comment Share on other sites More sharing options...
Lance Posted April 5, 2005 Share Posted April 5, 2005 The caps should not heat up that much. Remember they are oil filled. Also, computer psu's can supply a ton of current. Most of them can supply 50 amps on the 5v rail. Link to comment Share on other sites More sharing options...
5614 Posted April 5, 2005 Author Share Posted April 5, 2005 OK, fine, explained. Remeber that: enery loss as heat in wires = current squared x resistance 50A (squared in the equation!) explains all.... thanks man Link to comment Share on other sites More sharing options...
Tommahawk Posted April 9, 2005 Share Posted April 9, 2005 PSU = power supply unit What I don't get is that no matter what I do the PSU fans always belt out warm air! I mean' date=' what the heck is going on in there that produces [u']sooooo[/u] much heat? That is a good thing. Heat has to do with efficientcy. Higher efficientcy PSU like the Antrc Phantom 5 produce less heat, make better use of electricity. Most of the heat comes from the approx 6 MOSFETs in the PSU. Link to comment Share on other sites More sharing options...
5614 Posted April 10, 2005 Author Share Posted April 10, 2005 It's interesting that a really old PSU I have only has 4 MOSFETs, anyway, I have worked with MOSFETs before, but they do not produce much heat... I would have assumed it's the high current going through them which produces this heat? And I suppose its entirely logical to say that more expensive ones don't produce as much waste energy (in the form of thermal [aka heat] energy). Link to comment Share on other sites More sharing options...
ed84c Posted April 10, 2005 Share Posted April 10, 2005 http://www.silentpcreview.com/article227-page3.html This maybe of interest. As far as MOSFETs go, they do in my (limited) experience produce a lot of heat, in comparsion to other components, infact if you are using one in a circuit which isn't allready cooled, a small heat sink is a good idea for it. Link to comment Share on other sites More sharing options...
5614 Posted April 10, 2005 Author Share Posted April 10, 2005 Well the MOSTFET I used most recently was running at about 1A, which is quite a lot for a battery powered circuit, I placed a small heat sink on it. 50A sure as hell would produce a lot of heat. Link to comment Share on other sites More sharing options...
ed84c Posted April 10, 2005 Share Posted April 10, 2005 What circuit was it? Link to comment Share on other sites More sharing options...
ed84c Posted April 10, 2005 Share Posted April 10, 2005 Also on thinking about it; there are some pretty beefy resistors in a PSU. This could contribute some more heat. Link to comment Share on other sites More sharing options...
5614 Posted April 10, 2005 Author Share Posted April 10, 2005 It was a r/c test thingy, I intended to mod the output using a relay but the circuit never worked, and it was 1.5A, oh well, the ferrite rods are useful! Design found here: http://www.redcircuits.com/Page55.htm (It's Q2 on the transmitter) he he, hot resistors... I just burnt out 3 resistors in this circuit because the current was too high! I ended up just using a wire! And as for resistors in the PSU, looking in the one behind me, I couldn't find many large resistance resistors, I mean, the biggest I could see was 200Ω, it was rated 5W.... oh yeah, and a red red black gold, that'd be, wait, thats only 22Ω anyway! Why would you want a large resistor inside a PSU? I mean, that'd be a waste of power! Link to comment Share on other sites More sharing options...
ed84c Posted April 10, 2005 Share Posted April 10, 2005 When i said beasty, i meant large current ones, i.e. the big blue ones, hence a resitor for a large current pumping out more heat than a smaller one for a small current. Link to comment Share on other sites More sharing options...
5614 Posted April 10, 2005 Author Share Posted April 10, 2005 There are a few resistors in this PSU... but as I said there are not really any big ones, big current, voltage, resistance, wattage or anything! Link to comment Share on other sites More sharing options...
ed84c Posted April 10, 2005 Share Posted April 10, 2005 hmmm thats odd i vaguely remember finding some large ones in an old PSU that i had, maybe it was because the PSU was so old, and inefficeint, so it needed a massive current! Link to comment Share on other sites More sharing options...
5614 Posted April 10, 2005 Author Share Posted April 10, 2005 Well there would have been large caps.... As Lance said even new PSUs supply a lot of current. Maybe the older components couldn't withstand the high current... at the same time this one I'm looking at now is about 10 years old, I've seen inside newer ones too, never really noticed any big resistors, definately not in this 10yr old one behind me because I've just been looking! Link to comment Share on other sites More sharing options...
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