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Thread: operating frequency

  1. #1
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    operating frequency

    i am interseted in building a car computer. th only problem i am having is powering the computer. i am way to chp to buy a dc-dc converter or an inverter for that matter, but i do hav some big transformers lying around. what i am asking is is if th power supplies in computers can run on different frquncys than 60 hz, or on pulsed dc?

    another qustion is, i hav a 486 i was gonna us for the comp and i wonder if will support large drivs lik in the gigabyte range

  2. #2
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    Quote Originally Posted by cirvin
    i am interseted in building a car computer. th only problem i am having is powering the computer. i am way to chp to buy a dc-dc converter or an inverter for that matter, but i do hav some big transformers lying around. what i am asking is is if th power supplies in computers can run on different frquncys than 60 hz, or on pulsed dc?

    another qustion is, i hav a 486 i was gonna us for the comp and i wonder if will support large drivs lik in the gigabyte range
    Most computer pwr supplies will work with from either 50hz or 60hz AC....pulsed DC will NOT work. DC-DC convertors are the optimal choice, but if you are on a budget (everyone is to some extent) I would recommend a AC to DC convertor...you probably get one for $35 - $50

    I wouldn't recommend using a 486 in your car it's so slow, outdated and doesn't use an ATX power supply look at what you can get for $50

    http://cgi.ebay.com/ws/eBayISAPI.dll...category=51097

  3. #3
    Constant Bitrate henkbliek's Avatar
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    A PC power supply can be modified to run from DC input. In fact on of the first parts at the input is a rectifier.
    This is kind of useless though as this DC is ~300V.

    white bream
    working on a trilogy: CARGO - UNIGO - MERGO
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  4. #4
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    Interestingly enough, I been thinking if its possible to modify the input parts of the standard 240V ATX PSU such that it can work with 12V.

    I dont have a spare PSU right now, but I think it may be worth a look

  5. #5
    FLAC DodgeCummins's Avatar
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    Interesting theory.

    The first thing the AC power goes through is a step down transformer. If it is a one winding step down, then you could supply that voltage to the rest of the power supply for the rest of the regulation.

    If it is a multiwind step down, then you will have to supply multiple voltages to the rest of the regulation.

    (if you do all that work to supply voltages...what do you need the psu for)

    So in theory it might be possible to modify a PSU...but most likely not.

  6. #6
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    so it can't run on like 400 hz? watif i use a 555 timer and ti the output and trigger to an op amp, having the trigger in the inverting side and the out on the non inverting sid, then use that to driv a transformer through a 2n3055?

  7. #7
    Raw Wave Rob Withey's Avatar
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    Quote Originally Posted by DodgeCummins
    The first thing the AC power goes through is a step down transformer.
    I haven't seen a modern PC power supply that does this. Most that I have seen (as henkbliek said) put the AC through a rectifier to convert it to high voltage DC. Then it gets switched through the primary of the transformer, with the regulator controlling the switching transistors.


    Rob
    Old Systems retired due to new car
    New system at design/prototype stage on BeagleBoard.

  8. #8
    FLAC DodgeCummins's Avatar
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    Very interesting reading...in the old days switching powersupplies were not well received.

    http://www.howstuffworks.com/power-supply.htm
    http://www.epanorama.net/links/psu_computer.html

    I stand corrected...

    So where does one get 120vdc...(US current)

  9. #9
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    if they rectifiy it before using it, then it should run at any frequency , or even at dc right?

  10. #10
    Raw Wave
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    http://www.technick.net/public/code/index.php

    Check CIRCUITS > POWER SUPPLY

    Yup its DC at about 300V though.

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