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Power Supply Question — Parallax Forums

Power Supply Question

Invent-O-DocInvent-O-Doc Posts: 768
edited 2012-05-21 01:09 in General Discussion
I've been thinking about getting a new desktop power supply and have been looking at 0-18V/0-3A models at MPJA. There are two models, one is a temporary buy that is $49.95 with a max ripple of <200mV and the other is one they have in stock all the time for $59.95 that has a max ripple of <1mV.

Question - is this ripple only an issue when pumping out high amperage??? (I don't use much current and currently use couple home-mades that use a wall wart hooked to an LM317 and a rotary switch to give 3.3, 5, 7, 9 or 12 V) - I'm trying to figure if it is worth the extra ten bucks to get the better rating.

Thanks for your thoughts!

Comments

  • kwinnkwinn Posts: 8,697
    edited 2012-05-20 16:34
    In most cases 200mV of ripple is not a problem. My concern would be that they have used second rate components that may fail early. Personally I would spend the extra 10 bucks.
  • Duane C. JohnsonDuane C. Johnson Posts: 955
    edited 2012-05-20 19:29
    Hi Invent-O-Doc;

    Clearly Item Number: 9600 PS is superior to Item Number: 9615 PS.

    The 9600 PS is a linear supply. This makes the output much cleaner. For "Lab work" the clean output will not add extra headaches when trouble shooting sensitive circuits.

    The 9615 PS has 200mV ripple mainly because it is a switching supply. Yes, it will run cooler because it would be more efficient. I would think the ripple would be there even at low loads. Don't get me wrong, if you will use it to just power up things that have there own regulators then no problem.

    For circuit design, especially of analog circuits, the linear supply is always the way to go. Well worth the extra 10 bucks.

    Heck, I would get 2 of them.

    Oh I forgot, the 9600 PS has binding posts so you can connect wires directly. Yea, it will also accept banana plugs too.

    Duane J
  • frank freedmanfrank freedman Posts: 1,983
    edited 2012-05-20 23:47
    Go with the lowest ripple you can. You may use them one day in an analog or mixed application. Then the units with the higher ripple will play 7734 with your opamps and cause you many rypes of grief. Of course you may benefit from all the exgra troubleshooting experience chasing intermitent problems.

    Frank
  • LeonLeon Posts: 7,620
    edited 2012-05-21 01:09
    I use one of these little Lascar switchers:

    http://www.lascarelectronics.com/temperaturedatalogger.php?datalogger=125

    Ripple/noise is 100 mV.
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