12v to 19v PS overheated = noise :/

Discussion in 'The Projects Forum' started by LaZyLuke, Apr 21, 2010.

  1. LaZyLuke

    Thread Starter Active Member

    May 10, 2009
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    Hi.

    So I have another noise source since this morning in my audio. I had this PS (12v-19V converter) for 1 month, it was poorly wired for few weeks, so I rewired it last night and realized that the PS start BOILING - it was so hot that I could touch it- I was going to attach an huge external heat sink today but I was too late as it probably fried over night.... (All i did was provide proper connection for two wires, nothing else... so my question is:

    should i change the FET's that are heating like crazy right now for ones with better amp rating? (this thing came straigh from hong kong so quality is .... well you know) and what will you guys recommend the ones that are in there are:

    IRF244N

    two of MBR20100CT

    K2996- not sure what is it , package looks like a cross between TO220 and TO247 so im not sure its an FET...

    OR maybe I can build one myself with some good components that wont crap out - I need 3.7amp at 18V minimum (laptop will work with 18-20V)...

    My 12V DC source is a computer PS (there was no noise from it before so it cannot be the source from it)

    Please help because this is VERY annoying right now... ;/
     
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  3. LaZyLuke

    Thread Starter Active Member

    May 10, 2009
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    well that wont quite solve my problem since it will introduce a ground loop- i especially got a 12v DC to 19 v DC converter for that reason....but thanks anyway
     
  4. retched

    AAC Fanatic!

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    ?? I didnt see any thing about a ground loop.

    oh.. from the previous thread?

    I thought you took care of that.

    However I dont understand what the difference would be in getting a quality item to replace the bad one rather than trying to band-aid together an already proven bad power supply.

    Basically what you are trying to do is turn your power supply into a quality one.

    Crap-can it.
     
  5. LaZyLuke

    Thread Starter Active Member

    May 10, 2009
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    nono- im totally fine with getting a quality 12v DC to 19V dc converter (within a reasonable price)- the problem with a normal power supply that powers from a wall is that I'm gonna have a noise... I couldnt find a "quality" 12v dc to 19 V dc ps - they all come from china these days and the US made are $60 retail (I doubt this is a reasonable price for this kind of equipment)...

    PS- my solution for the ground loop was to use the 12V from PS as a power source for my laptop and lift the ground from the monitor)- worked flawlessly (later I will buy the ISO bar)

    PS2-for future reference im from Canada- the site with a PS doesn't ship to Canada :/
     
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    AAC Fanatic!

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    AAHHhh.. It would serve us all better if you would add your location to your profile. That way when we spend time looking for stuff for you, we will know your location and be better informed as to what will be accessible to you.

    Ok. So you want to try a IC switch then?
     
  7. LaZyLuke

    Thread Starter Active Member

    May 10, 2009
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    Ok ;] my bad- My contact info is updated, and Yes (if IC-switch would turn 12V dc into 19V dc I would be very happy to try it... I tried looking it up but I couldn't find anything useful about it)- thank you very much for responses

    I found something like that but I don't need all the fancy controlling programing options- but the compact size and lack of heat sinks seems like its a little efficient piece:

    http://www.mini-box.com/DCDC-USB

    PS: Will this one work?:

    http://www.mp3car.com/vbulletin/att...squema-fonte-notebook_para-ligar-no-carro.pdf

    apperently there is a mistake and R9 and R10 are specified as 6.8 kohm where they should be 6.8 ohm
     
    Last edited: Apr 22, 2010
  8. LaZyLuke

    Thread Starter Active Member

    May 10, 2009
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    One more thing- when im looking for an converter like that- should I look for more amps then i need or less (or exact number?)- I have heard that PS like that with more amps can damage the battery however from what I have learned it will be better to provide more MAX amp then i need (not sure about this exact application)
     
  9. retched

    AAC Fanatic!

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    Amps are taken, not given.

    If you have a 10,000,000 amp battery, and a little light bulb that is 10mA, the light wont explode. It will DRAW the 10mA it needs. The battery wont GIVE the light 1,000,000 amps.

    So the more Amperage, is not necessarily better. It will usually be larger, and more expensive. So being around what you need or a little more is usually good.

    If you may want to expand a circuit in the future, Its good to have extra amperage. Just look in your PC. They come with big supplies to (try to) handle add-on hard drives, memory, and the such.

    So if you can get a PC that is 2A more than your original for the same price as an exact match, it would be fine.
     
  10. LaZyLuke

    Thread Starter Active Member

    May 10, 2009
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    I just came across:

    http://webench.national.com

    And they came up with some design- Can you please tell me if this is worth to build? (I may get the parts from old PS or from electronic shop at my work).... i just don't trust automated "designers" :]

    PDF printout of the schematic and list of components and some graphs that webench gave me:

    http://www.mediafire.com/?tmvzne2erzt
     
  11. retched

    AAC Fanatic!

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    I cant view the mediafire attachment. Can you just have AAC host it?

    Just attach it to the post in 'Go Advanced'
     
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