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S-100 Power Supply Design Question

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    #31
    I dug through the drawers and found a 12VDC 3A switcher that will do for now, mainly just to run the fans.

    The case I chose - CoolerMaster HAF XB - is roomy enough for me to run the PSUs side-by-side instead of stacked. I think I'll get better airflow around them and, attached to an aluminum base plate, sort of a heat sink as well. Plus the plate lifts out with everything attached if need arises. The chassis is exceptionally deep; there is an additional 7 inches above the "mezzanine" rails, on which I will mount the backplane, cards and cage.

    Pics attached.

    -CH-

    PSU_Array1.jpg PSU_Array2.jpg PSU_Array3.jpg PSU_Array4.jpg
    Last edited by clh333; February 25, 2021, 05:34 AM.

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      #32
      That's a nice looking case. Mounting the board on rails kind of reminds me of the Altair.
      Rich
      Web site: http://cini.classiccmp.org/
      Web site: http://altair32.classiccmp.org/

      Comment


        #33
        Never seen an Altair, or an IMSAI, either, for that matter. I considered finding a "legacy" machine but I thought better. Not so much for the cost, as this project will probably equal that, but for the educational value and because I thought it better to start with new components - some old ones are becoming unobtainium - and because I didn't want to commit the mortal sin of sending a classic to an early grave.

        -CH-

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          #34
          Good thinking. I have both and they are very finicky. That's why, like you, I have a new system to play with.
          Rich
          Web site: http://cini.classiccmp.org/
          Web site: http://altair32.classiccmp.org/

          Comment


            #35
            An additional question has arisen: How to specify (name, locate, purchase) the "lifting levers" that sit at the upper corners of a 5x10" S-100 card? I'm building a cage but will need to know how high the top lip should be.

            Thanks for the info.

            -CH-

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              #36
              "card ejector"
              mouser has stock

              joe

              Comment


                #37
                Thank you. Also available at Newark. Datasheet suggests top of cage be same height as top of card. QED.

                -CH-

                Comment


                  #38
                  Originally posted by clh333 View Post
                  Thank you. Also available at Newark. Datasheet suggests top of cage be same height as top of card. QED.

                  -CH-
                  The ejector tab is the same hight as the board edge. But cards are not the same size. Mine vary by almost 1/10 in. I picked the shortest card I have and made the cage hight 1/16 inch shorter. Want to be sure the cards bottom out in the connector and not on the guides.

                  joe

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                    #39
                    Originally posted by jlang View Post
                    The ejector tab is the same hight as the board edge. But cards are not the same size. Mine vary by almost 1/10 in. I picked the shortest card I have and made the cage hight 1/16 inch shorter. Want to be sure the cards bottom out in the connector and not on the guides.

                    joe
                    It would then depend on the offset of the hole at the corner of the board. You'd want the hole to be such that the ejector does not restrict sufficient travel of the board in the connector.
                    Still, the connector doesn't make the connection, to the board, at the bottom of the connector. Look at the board and note where the wiping mark is for your particular connector. As long as it is inserted far enough to be about 0.10 inch beyond the wiping mark, it will be enough to work. Bottoming of the connector is not needed. In fact having it not bottom out will help from having connectors broken by forceful insertions.
                    Dwight

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                      #40
                      Thanks, gents, for your responses. The ejectors I ordered from Newark haven't arrived yet so a test fit isn't possible, but the cage (walnut) isn't fully assembled, either, so I may have some wiggle room. If I manage to break a connector through forceful insertion I will be quite surprised. Not looking forward to replacing one, but I do have a spare.

                      This has been a learning project and as such has taken a number of new directions already. Two steps forward, etc. I'll report back when I get it sorted.

                      Thanks again,

                      -CH-

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                        #41
                        Progress to date: Extractors fit the cards, cards fit the cage, cage fits the chassis.

                        Pics attached.

                        -CH-

                        TestFit1.jpg TestFit2.jpg

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