computer supply in project?

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Mike
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computer supply in project?

Post by Mike »

In another post, I asked about the size of a transformer for my subwoofer using an LM3886T. Instead of spending the $50 for a suitable transformer, I thought about a computer PS. I have a 250W AT supply. It can produce +12V @ max of 9.6A, but -12V at max of .5A. Will having the 9.6A and the 05A even work, and if so, will it work better than my 48VCT @ approx 1A transformer?
bodgy
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Re: computer supply in project?

Post by bodgy »

Only the +5v supply is normally regulated on computer SMPS's, you need to provide a minimum load at all times, so that it either doesn't burn up or produce loud annoying ticking sounds.<p>For the audio heavy filtering may be needed.<p>But you still need an inverter to supply the mains side of the SMPS if in a car.<p>Why not look and see if you can get surplus power supplies at plane/train or boat chandlers - most of the DC supplies in those run at 48v DC. Or if you have a very friendly Bosch place near you (that is Bosch as in Company not as in German), they may be able to help with one of their 48v alternators and accessories.<p>Soon all new cars will almost certainly be running on 48v electrics - Mercedes already have a top of the line car either in production or about to go into production using the new supply standard.<p>Colin<p>Colin
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i_myself_matthew
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Re: computer supply in project?

Post by i_myself_matthew »

You would almost certainly need more than one computer power supply. I have strung computer supplies in series before, but I used the 5v line for my application. You would need to put on a load resistor on the 5v line for it to regulate properly. You could string two supplies together using the +12v lines and have lots of power (series current is the guide I used). <p>It is important to make sure that one of the supplies "floats" so that its output is not tied to ground. Otherwise, you short one supply directly across ground. Not good. <p>"Better" is a hard term to assess. There will be more noise on the line due to the design of a switching power supply. I don't know what effect this would have on an audio system, because it is ultrasonic (more than 20kHz). As my computer power supplies were free, it was a lot cheaper to make a high current (20A) supply this way than buy a big transformer. It has the potential to be more efficient, but I'm not sure what would be the break even point because of the load resistors on the 5v line.<p>my two cents
-Matthew
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Mike
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Re: computer supply in project?

Post by Mike »

I guess I won't do that, since I don't need the 5V. Actually, I might be able to use 5V for a crossover. Does the +,- and gnd need to be used for the 5V? Also, would the different currents for the + and - be OK? Finally, by Bosch, do you mean the tool company?
bodgy
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Re: computer supply in project?

Post by bodgy »

I suppose so - he says cautiously.<p>Bosch electrical/electronics/tools are all parts of the same company - Bosch spark plugs for instance. I only say cautiously because it may be the Bosch in the US is a US company that has things under licence from BoschAV.<p>Like here in Ozland NEC and Sharp are the NEC and Sharp that we all know, plus there are companies with the same name who are wholey Oz owned who just have a franchise to sell some of the above companies items. <p>colin
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