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Chat_Ghosty's PSU

Discussion in 'Power Electronics' started by Chat_Ghosty, Jul 1, 2012.

  1. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Look at the label under output, most have the rates max output on them for each voltage line...
     
  2. Chat_Ghosty

    Chat_Ghosty

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    Jun 30, 2012
    Nice to meet you CocaCola.

    The thing about the PSU is its not Retail. But there is Some lettering on the Inside that I think might be a Clue. I posted a Image of it about Two pages back. Ill repost.

    The out side of the Drive says: 100 - 240V ~ 0.27 - 0.17A @ 50/60Hz.
    On the Drive it's self: +5v @ 1A and +12v @ 0.7A

    All I know from that is the PSU must be at least 1A.

    The PSU is just a Blank Box because you would never see it unless you take apart the Drive.

    Inside the PSU it Reads: F1 T2AH 250V.
    I think the F1 means Fuse 1, Because its right under the Fuse.
    But I think the 2AH Might be 2 Amp*Hour.

    [​IMG]
     

    Attached Files:

    Last edited: Jul 3, 2012
  3. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,266
    Nov 28, 2011
    Yes, that rating is for a replacement fuse. Fuses are rated in amps, not amp-hours. Batteries are rated in amp-hours. T2AH is a 2 amp "time-delay" fuse (i.e. not quick-blow - it takes a short time to blow, so it will withstand the inrush current when the supply is turned on).

    I think the H probably means high rupturing capacity. This means it's mechanically strong enough so that it won't break or crack even if it blows violently because of a sudden high-current fault. The fuse in the holder is clearly a ceramic fuse, not a glass one (glass ones don't have a high rupturing capacity). Can anyone confirm that the H in the description means HRC?

    Anyway, that fuse is in the input circuit, so its ratings don't directly relate to the output current ratings. But you found those - 1A on the 5V rail and 0.7A on the 12V rail.
    If those numbers are marked on the power supply, they will be the power supply's ratings. If they're marked on the device that the power supply is connected to, they will be the current consumption of that device, and the power supply's output current ratings will be at least that high, assuming the power supply has been properly matched to the device.
     
  4. Chat_Ghosty

    Chat_Ghosty

    49
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    Jun 30, 2012
    That's what I was thinking.

    The 12v @ 0.7A and 5v @1 A Is on the CD Drive. I would Imagine that the Rates are Matched Properly.

    The output Current is going to be Higher then the Input Current. No?
    The Cooling for all the Parts have no Real Heat sink and No Fan. They are just mounted to the Case.

    If you was wondering. The Drive is a Panasonic SCSI CD Drive. Model LK-MC605S. i don't know how Much I will find on the Drive because of how Old it it. I mean it's around MS-DOS. So about Late 80s Early 90s
     
  5. Chat_Ghosty

    Chat_Ghosty

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    Jun 30, 2012
    Anything you Guys think I should Pick up at Radio Shack?

    I would love a PLC. :)
     
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Right. If those figures are marked on the drive, then the power supply should be rated to deliver at least that much current on those voltage rails.
    The power supply doesn't have any heatsinking or fan because it will be a switching power supply and these are relatively efficient so not much heat is dissipated.
     
  7. BobK

    BobK

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    Jan 5, 2010
    The metal frame is being used as a heat sink.

    Bob
     
  8. Chat_Ghosty

    Chat_Ghosty

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    Jun 30, 2012
    Nice to meet you Bob

    Yes, I ment there is not Major heat sink like normal PSU have. Then again Normal PSU have Fans, but because this is a much Lower Current then Normal Ones.

    The point of me say what I did was Clarification that because there is not Major Heat Sink then there is not Much of a Energy Loss because of heat.

    Anyway, Ill try and see if I can find a Cheap De-Soldering Gun at RS because I lost mine. I noted a Bunch of IC on even the Basic PSU I have. Any Idea what those are for?

    I would like just for Clarification.

    120V AC enters a Bridge Rectifier that turns the AC in DC 120v (or 400v?), then Switched to 20Khz(ish) before it Inters a Transformer, Go inter a Voltage Regulator, then Gets Smoothed By Capacitors. And now you have say 12v Rail?
     
    Last edited: Jul 3, 2012
  9. BobK

    BobK

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    Jan 5, 2010
    Correct, except the rectified 120V will be more like 170V. The peak voltage of a sine wave is sqrt(2) times the RMS voltage, and a bridge rectifier with smoothing capacitors will produce something close to the peak voltage when not loaded.

    Bob
     
  10. duke37

    duke37

    5,254
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    Jan 9, 2011
    Some switch mode supplies rectify the input with a bridge for 230V, giving 325V and use a voltage doubler for 110V, giving 311V.
    I was given one to repair after it was brought back into the UK and not switched to 23V!
     
  11. Chat_Ghosty

    Chat_Ghosty

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    Jun 30, 2012
    Ok Great Just making sure.

    Duke: Are you sure it is 23v and not 230v?
     
  12. duke37

    duke37

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    Jan 9, 2011
    You are right, it is 230V, I know because it bites.
    I missed the 0 but I did find the caps key for V!
     
  13. Chat_Ghosty

    Chat_Ghosty

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    Jun 30, 2012
    I did some shoping and I got a Bigger Project Box, Some De-soldering Braid, and 22 Gauge Wire.

    I looked online and It said the Wire can only Carry ~0.9A

    I know 16 Gauge can Pull at least 15A.

    I did not Open the Package. So I can still return it to Radio Shack. I think.
     
  14. MrEE

    MrEE

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    Apr 13, 2012
    A word of warning about power dissipation. with over 15 V at the input and 1.5V at the output (worst case difference) and say at 3A current you are burning about 40W by the regulator!!

    Another idea for added current. Instead of buying an expensive regulator, I'd use a standard LM317 for example and add pass transistor.
    http://www.google.com/search?q=lm31...8NKbO2AWy56SABw&ved=0CHAQsAQ&biw=1736&bih=847

    there are plenty of info on this (see link above)
     
  15. Chat_Ghosty

    Chat_Ghosty

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    Jun 30, 2012
    Nice to meet you MrEE.

    I don't know how far back you have read, but I think it was Steve stated the Thermal Problem.

    I going to stick with 5V and 12v For now.

    As of Terminals. Can I use a Thick Bolt and Nut? Cheap and Easy!

    BTW. Happy 4th of July. Sorry Duke! ;)
    I don't know if Zealand or Australia has a Independence Day.
     
  16. Chat_Ghosty

    Chat_Ghosty

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    Jun 30, 2012
    I think I have the info i need to work on my Project for now. Thank you all for your help.
     
  17. Chat_Ghosty

    Chat_Ghosty

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    Jun 30, 2012
    Last edited: Jan 6, 2013
  18. davenn

    davenn Moderator

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    Sep 5, 2009
    no it wont

    your bridge rectifier diodes are back to front for a start

    Dave
     
  19. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,266
    Nov 28, 2011
    Are you trying to design a mains-powered switching power supply?

    I've re-read this thread and it seems you were talking about a problem with a small power supply with just 5V and 12V outputs. Now you want to design a new one from scratch?

    I don't want to sound insulting, but you're way out of your depth. There are a number of mistakes in your design that demonstrate that you're an electronics newbie. Designing a mains-powered switching supply is a significant project even for an experienced electronics engineer.
     
  20. Chat_Ghosty

    Chat_Ghosty

    49
    0
    Jun 30, 2012
    Dave. Why am I thinking that the Line on the Diode is the Negative side?

    Are you thinking Electron or Conventional Theory.

    Kris. I understand what you mean. Don't worry about insulting me. I knew there would be a ton of Problems as the Article was kind of just a Guild. I am a electronic Noob. I'v read one book on Digital Electronics and my Main Education is with Industrial Electrical. (Like how to wire houses and power lines). So electronics is kind of new. The small 5v and 12v PSU. I decided I can just use a LM7805 and LM7812 and Two Transistors.

    I like to jump in the deep end, mess up, and learn.

    Other then the Bridge Rectifier. What jumps out first?
     
    Last edited: Jan 6, 2013
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