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Re: [Electronics_101] newbie Q: want to substitute a wallrat power supply...

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  • jong kung
    Jon, ... At the very least, you can wire four 9v batteries in series and hope 36v is not too much.  Or you can add LM317 in addition and lower the voltage
    Message 1 of 13 , Jun 1, 2009
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      Jon,


      > I have a HP Photosmart printer used that I got without a pwr supply.
      > Sticker says use +32v, 660mA.

      At the very least, you can wire four 9v batteries in series and hope 36v is not too much.  Or you can add LM317 in addition and lower the voltage from 36v down to 32v.  The whole solution would be less than $10.

      If that works, then you can invest in more permanent solution.


      Jong





      [Non-text portions of this message have been removed]
    • jong kung
      Jon (Dennis), ... LM317 (and a trimmer and a couple resistors). LM317 are ... Vout = 40V, I think the MAX input voltage on LM317 is 40v.  So I don t think
      Message 2 of 13 , Jun 1, 2009
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        Jon (Dennis),


        > You can build a quick-and-dirty 32V supply by using your adapter
        > and an
        LM317 (and a trimmer and a couple resistors). LM317 are
        > rated for Vin -
        Vout = 40V,

        I think the MAX input voltage on LM317 is 40v.  So I don't think that would work (unless somebody can say from experience that it can handle more voltage in practice).

        http://www.national.com/mpf/LM/LM317.html


        Jong























        [Non-text portions of this message have been removed]
      • KB9BVN
        Jon, You can whip up a LM317 based voltage regulator on a piece of PCBoard the size of a quarter. http://diyaudioprojects.com/Technical/Voltage-Regulator/ Set
        Message 3 of 13 , Jun 1, 2009
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          Jon,

          You can whip up a LM317 based voltage regulator on a piece of PCBoard the
          size of a quarter.

          http://diyaudioprojects.com/Technical/Voltage-Regulator/

          Set R1 to 240 Ohms and R2 to 6K Ohms and you get 32.5 volts out. This reg
          is able to handle up to 1.5A

          If you want to try it, let me know and I'll send you a couple LM317's to
          play with.

          73 de KB9BVN
          Brian Murrey



          ----- Original Message -----
          From: "jonathan" <jesteele1948@...>
          To: <Electronics_101@yahoogroups.com>
          Sent: Monday, June 01, 2009 6:42 PM
          Subject: [Electronics_101] newbie Q: want to substitute a wallrat power
          supply...


          >I have a HP Photosmart printer used that I got without a pwr supply.
          >Sticker says use +32v, 660mA. I know in some situations a substitute of
          >greater capacity will work with some devices. I have a "telco" wallrat
          >rated 48V, I think it's 1Amp. No problem putting on it a "barrel" plug for
          >proper fit. Will it damage the printer? Is there an easy way to protect
          >the printer, like with in-series resistor? I have minimal test equipmt
          >(VOM). Don't want to buy the proper p.s. since this printer may already be
          >internally damaged.
          > Don't mind doing some reading for greater understanding. Thanks to all.
          > Jon
          >
          >
          >
          > ------------------------------------
          >
          > Please trim excess when replyingYahoo! Groups Links
          >
          >
          >
        • Dennis
          Hi Jong, ... I checked the datasheet before making my post. The LM317 is a floating regulator (there s no hard ground connection) and is rated for an
          Message 4 of 13 , Jun 1, 2009
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            Hi Jong,
            --- In Electronics_101@yahoogroups.com, jong kung <jongkung01@...> wrote:
            > I think the MAX input voltage on LM317 is 40v.  So I don't think
            > that would work (unless somebody can say from experience that it
            > can handle more voltage in practice).

            I checked the datasheet before making my post. The LM317 is a "floating" regulator (there's no hard ground connection) and is rated for an input-to-output differential of 40V max. Hence my comment about not setting Vout to less than 8V which would exceed the max rating.

            Regards,
            Dennis
          • jonathan
            Brian et al; All your replies have been useful. Brian s solution seems safest and pretty simple. I was hoping for an even simpler rig (like the 4x 9v
            Message 5 of 13 , Jun 3, 2009
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              Brian et al;
              All your replies have been useful. Brian's solution seems safest and pretty simple. I was hoping for an even simpler rig (like the 4x 9v batteries (:-) ); now I have to dig up my box of resistors and pots and see if I have everything. A perm solution appeals to me because I may use the printer regularly if its prints are good. It's cute like a puppydog.

              Really appreciate the link. Haven't soldered in years. Brian, I may email you for those volt reg. chips if mailing is straightforward, but not yet. Thanks for the offer.

              Jon

              --- In Electronics_101@yahoogroups.com, "KB9BVN" <kb9bvn@...> wrote:
              >
              > Jon,
              >
              > You can whip up a LM317 based voltage regulator on a piece of PCBoard the
              > size of a quarter.
              >
              > http://diyaudioprojects.com/Technical/Voltage-Regulator/
              >
              > Set R1 to 240 Ohms and R2 to 6K Ohms and you get 32.5 volts out. This reg
              > is able to handle up to 1.5A
              >
              > If you want to try it, let me know and I'll send you a couple LM317's to
              > play with.
              >
              > 73 de KB9BVN
              > Brian Murrey
              >
              >
              >
              > ----- Original Message -----
              > From: "jonathan" <jesteele1948@...>
              > To: <Electronics_101@yahoogroups.com>
              > Sent: Monday, June 01, 2009 6:42 PM
              > Subject: [Electronics_101] newbie Q: want to substitute a wallrat power
              > supply...
              >
              >
              > >I have a HP Photosmart printer used that I got without a pwr supply.
              > >Sticker says use +32v, 660mA. I know in some situations a substitute of
              > >greater capacity will work with some devices. I have a "telco" wallrat
              > >rated 48V, I think it's 1Amp. ...<snip>...
              > > Jon
            • jong kung
              Jon, ... pretty ... batteries (:-) ); I would think that 36 volts is close enough to 32v  that it should work.  But hey electronics is fun so play it safe.
              Message 6 of 13 , Jun 3, 2009
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                Jon,


                > All your replies have been useful. Brian's solution seems safest and
                pretty
                > simple. I was hoping for an even simpler rig (like the 4x 9v
                batteries (:-) );

                I would think that 36 volts is close enough to 32v  that it should work.  But hey electronics is fun so play it safe.

                =====

                > Haven't soldered in years.

                You can start with solderless breadboards.  If the printer is working condition, then you can get perfboards and project kits and wire them up.  :-)

                ====

                > I may
                email you for those volt reg. chips if mailing is straightforward

                The chips are just $2.29 at RS.  And that's at the high end.  At least at Radio Shack you don't have to pay $10 for shipping one chip.  If you want to buy a bunch, you can get them cheaper (but have to pay shipping).

                http://www.radioshack.com/product/index.jsp?productId=2062601


                Jong























                [Non-text portions of this message have been removed]
              • Mike Payson
                Just FYI, while you can certainly hack together a solution as others have suggested, you can buy a replacement power supply for ~$21 delivered on eBay:
                Message 7 of 13 , Jun 3, 2009
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                  Just FYI, while you can certainly hack together a solution as others
                  have suggested, you can buy a replacement power supply for ~$21
                  delivered on eBay:

                  http://cgi.ebay.com/HP-PHOTOSMART-PRINTER-POWER-SUPPLY-0950-4081-32VDC-94A_W0QQitemZ380106484014QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item58801ca92e&_trksid=p3286.m20.l1116
                  or
                  http://tinyurl.com/qv8k2l

                  Whether it's better to buy or adapt depends on how much your time is worth.

                  One thing that was never really explicitly addressed in your question
                  is that you cannot just randomly exceed the stated values on a power
                  supply. While many circuits will accept a higher voltage input, don't
                  do so unless you are certain. You are quite likely to damage or
                  destroy the device, and potentially even start a fire by exceeding the
                  voltage. You would -probably- be ok going a bit over, but 50% is
                  pretty likely to cause damage.

                  I think what you are thinking of is the current rating. The stated
                  current is the maximum the device will draw, so that is the -minimum-
                  current your power supply should provide. Since a power supply will
                  only deliver whatever current a device draws, anything that delivers
                  the stated current or more will be just fine. If you were really silly
                  and had deep pockets, you could use a 32V, 100A power supply to drive
                  the printer and it would work just fine. Kinda wasteful, but fine. :-)


                  On Mon, Jun 1, 2009 at 3:42 PM, jonathan <jesteele1948@...> wrote:
                  > I have a HP Photosmart printer used that I got without a pwr supply.  Sticker says use +32v, 660mA.  I know in some situations a substitute of greater capacity will work with some devices.  I have a "telco" wallrat rated 48V, I think it's 1Amp.  No problem putting on it a "barrel" plug for proper fit.  Will it damage the printer?  Is there an easy way to protect the printer, like with in-series resistor?  I have minimal test equipmt (VOM).  Don't want to buy the proper p.s. since this printer may already be internally damaged.
                  > Don't mind doing some reading for greater understanding.  Thanks to all.
                  > Jon
                  >
                  >
                  >
                  > ------------------------------------
                  >
                  > Please trim excess when replyingYahoo! Groups Links
                  >
                  >
                  >
                  >
                • Brian Murrey
                  Or maybe some nice guy will just give them to you.
                  Message 8 of 13 , Jun 4, 2009
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                    Or maybe some nice guy will just give them to you. <grin>



                    On Thu, Jun 4, 2009 at 12:49 AM, jong kung <jongkung01@...> wrote:

                    > The chips are just $2.29 at RS.  And that's at the high end.  At least at Radio Shack you don't have to pay $10 for shipping one chip.  If you want to buy a bunch, you can get them cheaper (but have to pay shipping).
                  • Jimmy Moore
                    Digikey gives free shipping if you pay by check. ... [Non-text portions of this message have been removed]
                    Message 9 of 13 , Jun 4, 2009
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                      Digikey gives free shipping if you pay by check.

                      On Thu, Jun 4, 2009 at 12:26 PM, Brian Murrey <kb9bvn@...> wrote:

                      >
                      >
                      > Or maybe some nice guy will just give them to you. <grin>
                      >
                      > On Thu, Jun 4, 2009 at 12:49 AM, jong kung <jongkung01@...<jongkung01%40yahoo.com>>
                      > wrote:
                      >
                      > > The chips are just $2.29 at RS. And that's at the high end. At least at
                      > Radio Shack you don't have to pay $10 for shipping one chip. If you want to
                      > buy a bunch, you can get them cheaper (but have to pay shipping).
                      >
                      >


                      [Non-text portions of this message have been removed]
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