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Protoboard from 12v — Parallax Forums

Protoboard from 12v

SeariderSearider Posts: 290
edited 2008-04-19 13:51 in Propeller 1
I know that the Protoboard is designed to run with an imput supply of 6-9 vdc. Has anyone designed a simple 12vdc to (6-9)vdc ?· I have been looking at Mouser and I can not seem to find any single chip regulators that fit the specifications. Most will out put 5vdc or 12vdc or they have very very small power capabilities.

Thanks

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Searider

Comments

  • RaymanRayman Posts: 14,813
    edited 2008-04-13 23:13
    I think the 7809 will give +9 volts...
  • SeariderSearider Posts: 290
    edited 2008-04-13 23:15
    Why thank you very much for your quick and perfect answer.

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    Searider
  • nohabnohab Posts: 96
    edited 2008-04-15 13:12
    Depending on how much current you need, you might be able to use 12V directly to the Protoboard.
    The voltage regulator on the input can handle much more than 12V, but due to the lack of a heatsink, it won't withstand high current.
    I have tried with 12V for the protoboard and a couple of LEDs, no problem, but I don't know exactly where the limit is.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2008-04-18 22:42
    Searider, you should be able to plug 12V directly in. We derate values to make sure things stay within a comfortable margin of safety, but you shouldn't have problems with 12V, except that the heat generated will be greater, but they are large enough regulators on the board to handle this extra heat.

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • Ken PetersonKen Peterson Posts: 806
    edited 2008-04-19 08:59
    We have added heat sinks to the 5V regulator on a couple of Proto boards. What we did is lift the regulator from the board and add a piece of copper foil with "wings" under it and then solder it back down. That might be easier than adding another regulator. I have never seen one shut down from getting too hot and we use them at 12V all the time. They do get pretty warm.

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    The more I know, the more I know I don't know.· Is this what they call Wisdom?
  • deiloohaydeiloohay Posts: 11
    edited 2008-04-19 13:21
    The LM317 is probably more readily available. Is the question about 12V because you want to use this in a car? (with engine running it will be more like 13.8V+)

    I bought this heatsink from Radio Shack that I was going to install on the proto board:

    http://www.radioshack.com/product/index.jsp?productId=2102856

    pRS1C-2265177w345.jpg

    It's good for 5W of heat dissipation, so if the 5V regulator had a Vin of 12V, should be good for more than 700mA!



    Post Edited (deiloohay) : 4/19/2008 1:41:42 PM GMT
  • Mike GreenMike Green Posts: 23,101
    edited 2008-04-19 13:51
    Another suggestion that I've used is to attach the heatsink to the regulator(s) using metal filled epoxy. The epoxy itself insulates the metal powder electrically, yet helps the heat conduction. Use a thin layer between the heatsink and the top of the regulator, yet work a small amount of the epoxy between the regulator tab and the heatsink. It's easier than lifting and resoldering the regulator as described above, but won't conduct the heat as well. I used this heatsink from RadioShack: www.radioshack.com/product/index.jsp?productId=2102857&cp=&pg=2&sr=1&origkw=heatsink&kw=heatsink&parentPage=search.
    See the photo here: http://forums.parallax.com/showthread.php?p=677691.

    Post Edited (Mike Green) : 4/19/2008 1:57:03 PM GMT
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