Loading ...
Sorry, an error occurred while loading the content.

Re: [softrock40] DC-DC converter for Ensemble RX II

Expand Messages
  • Alan
    ... Subject: [softrock40] DC-DC converter for Ensemble RX II ... I attach the Softrock v4 schematic. This uses the 5V USB power, there is no need for 12V for
    Message 1 of 22 , May 12, 2011
    • 1 Attachment
    • 66 KB
    ----- Original Message -----
    Subject: [softrock40] DC-DC converter for Ensemble RX II


    > I'm wondering if anyone has considered adding a dc-dc (5V to 12V)
    > converter chip such as a ST662 to provide power to the Ensemble RX II
    > board from the USB port rather than from an external 12VDC source?. The
    > ST662 is an 8 pin SO-8 smt device, and requires no inductors -just 4
    > capacitors. From what I have read, the board only requires 30mA, and any
    > USB port can easily supply this amount of current.


    I attach the Softrock v4 schematic. This uses the 5V USB power, there is no
    need for 12V for the RX. It is just dropped to 5V.
    The Ensemble may require a different smoothing transistor, I have not
    checked the specifications.
    I'm not sure anyone can predict if you will be troubled by USB noise. I
    tried something like this, a quick check showed no ill effects but I did not
    make it permanent.

    73 Alan G4ZFQ
  • Roger Critchlow
    Didn t Tony post in the last month or so about converting an Rx Ensemble II to plain USB power for his grand kids? As I recall he put some filtering on it,
    Message 2 of 22 , May 12, 2011
    • 0 Attachment
      Didn't Tony post in the last month or so about converting an Rx Ensemble II to plain USB power for his grand kids?   As I recall he put some filtering on it, but nothing complicated.

      -- rec --

      On Thu, May 12, 2011 at 11:49 PM, Alan <alan4alan@...> wrote:
       
      [Attachment(s) from Alan included below]


      ----- Original Message -----
      Subject: [softrock40] DC-DC converter for Ensemble RX II

      > I'm wondering if anyone has considered adding a dc-dc (5V to 12V)
      > converter chip such as a ST662 to provide power to the Ensemble RX II
      > board from the USB port rather than from an external 12VDC source?. The
      > ST662 is an 8 pin SO-8 smt device, and requires no inductors -just 4
      > capacitors. From what I have read, the board only requires 30mA, and any
      > USB port can easily supply this amount of current.

      I attach the Softrock v4 schematic. This uses the 5V USB power, there is no
      need for 12V for the RX. It is just dropped to 5V.
      The Ensemble may require a different smoothing transistor, I have not
      checked the specifications.
      I'm not sure anyone can predict if you will be troubled by USB noise. I
      tried something like this, a quick check showed no ill effects but I did not
      make it permanent.

      73 Alan G4ZFQ


    • Chris Cain
      The current on the 5v RX side (after the regulator) can not be more than a few milliamps so a set of 3 AAA cells would probaly Work fine and give a portable
      Message 3 of 22 , May 13, 2011
      • 0 Attachment

        The current on the 5v RX side (after the regulator) can not be more than a few milliamps so a set of 3 AAA cells would probaly

        Work fine and give a portable low noise solution if noise was a problem from using the USB 5V.

         

        Chris

         

         

        From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of ve3mic
        Sent: 13 May 2011 03:57
        To: softrock40@yahoogroups.com
        Subject: [softrock40] Re: DC-DC converter for Ensemble RX II

         

         

        Hi Sid,

        Yes, The potential noise generated from the converter was in the back of my mind and was curious if anyone had tried it. It would make it ideal for portable use -just a note/netbook computer, the Ensemble RX II, and an antenna! -no 12VDC
        Thanks.
        -Mike

        --- In softrock40@yahoogroups.com, "w7qjq" <sbjknox@...> wrote:
        >
        >
        >
        > --- In softrock40@yahoogroups.com, "ve3mic" <ve3mic@> wrote:
        > >
        > > I'm wondering if anyone has considered adding a dc-dc
        > > (5V to 12V) converter chip such as a ST662 to provide
        > > power to the Ensemble RX II board from the USB port
        > > rather than from an external 12VDC source?.
        > > The ST662 is an 8 pin SO-8 smt device, and requires
        > > no inductors -just 4 capacitors. From what I have read,
        > > the board only requires 30mA, and any USB port can
        > > easily supply this amount of current.
        > >
        >
        > Obtaining the required power is the easy part...keeping the switching hash out of the Rx may be a real chore but I'm sure can be done.
        >
        > $0.02
        > 73 Sid W7QJQ
        > Oklahoma
        >




        This email has been scanned for all viruses.

        Please consider the environment before printing this email.

        The content of this email and any attachment is private and may be privileged. If you are not the intended recipient, any use, disclosure, copying or forwarding of this email and/or its attachments is unauthorised. If you have received this email in error please notify the sender by email and delete this message and any attachments immediately. Nothing in this email shall bind the Company or any of its subsidiaries or businesses in any contract or obligation, unless we have specifically agreed to be bound.

        KCOM Group PLC is a public limited company incorporated in England and Wales, company number 02150618 and whose registered office is at 37 Carr Lane, Hull, HU1 3RE.

        118288 - KCOM Group UK Directory Enquiries. Calls will cost no more than 87p connection + 36p per minute including VAT from a KC or BT landline. Call charges from mobiles and other networks may vary. If you are calling from a mobile you will now receive your requested number via text message. You will not be charged for the text message.

      • janchristerlarsson
        Hello All, thanks for a great discussion group! And great kits from Tony, I am impressed how well they performe! I started SWL in the 60 s and using the SDR s
        Message 4 of 22 , May 13, 2011
        • 0 Attachment
          Hello All,
          thanks for a great discussion group!
          And great kits from Tony, I am impressed how well they performe! I started SWL in the 60's and using the SDR's gave me a boost! Maybe I should go for a HAM license...

          I tried to use a small recycled switch, VA0515dd1 (I have lot of those...), to generate the 12V(well 15V) .

          It did but I also got a (cracking) 'cloud' moving over the 40M band when testing, a temperature drifting overtone from the switch circuit (100khz). I wasn't able to eliminate it completely in my test setup. I tested with Lite II 40 m Softrock and the Ensemble II.

          I also tried to use a (switching) supply from some Mp3 player, but I found it was generating very much noise. I had to revert to my old, classic 12V supply.

          Would be very nice if somebody find a solution to power the Ensemble from USB only.

          regards
          Christer (SWL)
        • Thomas Bewick
          Chester, I would highly recommend you go for that licence! As an experienced SWL and SoftRock Kit builder you would have no trouble studying and passing the
          Message 5 of 22 , May 13, 2011
          • 0 Attachment
            Chester,

            I would  highly recommend you go for that licence!
            As an experienced SWL and SoftRock Kit builder you would have no trouble studying and passing the exams and it will add so much more to your radio experience and fun.

            I would recommend finding a local HAM club searching the internet and seeing if they give the tests and may even have some license classes available. And of course either the ARRL or Gordon West license manuals are a necessity,.

            Blessings to you in your endeavors,
            73
            Tom
            N2BEW


            On Fri, May 13, 2011 at 5:35 AM, janchristerlarsson <jan.christer.larsson@...> wrote:
             


            Hello All,
            thanks for a great discussion group!
            And great kits from Tony, I am impressed how well they performe! I started SWL in the 60's and using the SDR's gave me a boost! Maybe I should go for a HAM license...

            I tried to use a small recycled switch, VA0515dd1 (I have lot of those...), to generate the 12V(well 15V) .

            It did but I also got a (cracking) 'cloud' moving over the 40M band when testing, a temperature drifting overtone from the switch circuit (100khz). I wasn't able to eliminate it completely in my test setup. I tested with Lite II 40 m Softrock and the Ensemble II.

            I also tried to use a (switching) supply from some Mp3 player, but I found it was generating very much noise. I had to revert to my old, classic 12V supply.

            Would be very nice if somebody find a solution to power the Ensemble from USB only.

            regards
            Christer (SWL)


          • Alan
            ... Subject: RE: [softrock40] Re: DC-DC converter for Ensemble RX II ... Yes, I was forgetting the Si570 is fed directly from the USB power. As Roger said
            Message 6 of 22 , May 13, 2011
            • 0 Attachment
              ----- Original Message -----
              Subject: RE: [softrock40] Re: DC-DC converter for Ensemble RX II


              >The current on the 5v RX side (after the regulator) can not be more than a
              >few milliamps

              Yes, I was forgetting the Si570 is fed directly from the USB power.

              As Roger said Tony posted his method
              <http://groups.yahoo.com/group/softrock40/message/54144> He did not mention
              the method used in the V4 Softrock.

              73 Alan G4ZFQ
            • Sid Boyce
              These new regulators look like they could be useful replacements for the 78xx series which dissipate a lot of heat. In addition they can supply a negative
              Message 7 of 22 , May 13, 2011
              • 0 Attachment
                These new regulators look like they could be useful replacements for the
                78xx series which dissipate a lot of heat. In addition they can supply a
                negative voltage from a positive voltage input.
                http://www.elektor.com/news/k78xx-switch-mode-lm78xx.1806960.lynkx?utm_source=UK&utm_medium=email&utm_campaign=news
                http://www.mornsun-power.com/de/product_inf.aspx?typeID=62
                73 ... Sid.

                On 13/05/11 06:49, Alan wrote:
                > [Attachment(s) <#TopText> from Alan included below]
                >
                >
                > ----- Original Message -----
                > Subject: [softrock40] DC-DC converter for Ensemble RX II
                >
                > > I'm wondering if anyone has considered adding a dc-dc (5V to 12V)
                > > converter chip such as a ST662 to provide power to the Ensemble RX II
                > > board from the USB port rather than from an external 12VDC source?. The
                > > ST662 is an 8 pin SO-8 smt device, and requires no inductors -just 4
                > > capacitors. From what I have read, the board only requires 30mA, and any
                > > USB port can easily supply this amount of current.
                >
                > I attach the Softrock v4 schematic. This uses the 5V USB power, there is no
                > need for 12V for the RX. It is just dropped to 5V.
                > The Ensemble may require a different smoothing transistor, I have not
                > checked the specifications.
                > I'm not sure anyone can predict if you will be troubled by USB noise. I
                > tried something like this, a quick check showed no ill effects but I did
                > not
                > make it permanent.
                >
                > 73 Alan G4ZFQ
                >
                >


                --
                Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                Senior Staff Specialist, Cricket Coach
                Microsoft Windows Free Zone - Linux used for all Computing Tasks
              • Bruce Tanner
                I agree with Tom! 73, Bruce, K2BET
                Message 8 of 22 , May 13, 2011
                • 0 Attachment
                  I agree with Tom!

                  73,
                  Bruce,
                  K2BET
                  --------------

                  On 5/13/2011 5:41 AM, Thomas Bewick wrote:  

                  Chester,

                  I would  highly recommend you go for that licence!
                  As an experienced SWL and SoftRock Kit builder you would have no trouble studying and passing the exams and it will add so much more to your radio experience and fun.

                  I would recommend finding a local HAM club searching the internet and seeing if they give the tests and may even have some license classes available. And of course either the ARRL or Gordon West license manuals are a necessity,.

                  Blessings to you in your endeavors,
                  73
                  Tom
                  N2BEW


                  On Fri, May 13, 2011 at 5:35 AM, janchristerlarsson <jan.christer.larsson@...> wrote:
                   


                  Hello All,
                  thanks for a great discussion group!
                  And great kits from Tony, I am impressed how well they performe! I started SWL in the 60's and using the SDR's gave me a boost! Maybe I should go for a HAM license...

                  I tried to use a small recycled switch, VA0515dd1 (I have lot of those...), to generate the 12V(well 15V) .

                  It did but I also got a (cracking) 'cloud' moving over the 40M band when testing, a temperature drifting overtone from the switch circuit (100khz). I wasn't able to eliminate it completely in my test setup. I tested with Lite II 40 m Softrock and the Ensemble II.

                  I also tried to use a (switching) supply from some Mp3 player, but I found it was generating very much noise. I had to revert to my old, classic 12V supply.

                  Would be very nice if somebody find a solution to power the Ensemble from USB only.

                  regards
                  Christer (SWL)




                  __________ Information from ESET Smart Security, version of virus signature database 6119 (20110513) __________

                  The message was checked by ESET Smart Security.

                  http://www.eset.com
                • Alan Campbell
                  Aaah I see - a potential new mini project. A 5V - 12V converter in a USB Stick enclosure. Plug that into one laptop USB connector, and the Ensemble II into a
                  Message 9 of 22 , May 13, 2011
                  • 0 Attachment
                    Aaah I see - a potential new mini project.  A 5V - 12V converter in a USB Stick enclosure.
                    Plug that into one laptop USB connector, and the Ensemble II into a seperate connector. A DC lead (maybe looped thru some ferrite cores) to connect them.

                    My old laptop has USBs on left and right sides. That would increase the isolation.
                    You could have something here...

                    -- Al Campbell


                    Hi Sid,

                    Yes, The potential noise generated from the converter was in the back of my mind and was curious if anyone had tried it. It would make it ideal for portable use -just a note/netbook computer, the Ensemble RX II, and an antenna! -no 12VDC
                    Thanks.
                    -Mike

                    --- In softrock40@yahoogroups.com, "w7qjq" <sbjknox@...> wrote:
                    >
                    >
                    >
                    > --- In softrock40@yahoogroups.com, "ve3mic" <ve3mic@> wrote:
                    > >
                    > > I'm wondering if anyone has considered adding a dc-dc  (5V to 12V) converter chip such as a ST662 to provide
                    > > power to the Ensemble RX II board from the USB port  rather than from an external 12VDC source?.
                    > > The ST662 is an 8 pin SO-8 smt device, and requires  no inductors -just 4 capacitors. From what I have read,
                    > > the board only requires 30mA, and any USB port can  easily supply this amount of current.
                    > >
                    >
                    > Obtaining the required power is the easy part...keeping the switching hash out of the Rx may be a real chore but I'm sure can be done.
                    >
                    > $0.02
                    > 73 Sid W7QJQ
                    > Oklahoma
                    >

                  • janchristerlarsson
                    Thank s for the encouragement! I cannot decide what is most fun! I am now exploring the SDR hw s, the SDR software designs, listening to all the bands, digital
                    Message 10 of 22 , May 15, 2011
                    • 0 Attachment
                      Thank's for the encouragement!

                      I cannot decide what is most fun!

                      I am now exploring the SDR hw's, the SDR software designs, listening to all the bands, digital modes etc.

                      I even enjoy winding toroids...

                      Christer


                      --- In softrock40@yahoogroups.com, Bruce Tanner <bet110@...> wrote:
                      >
                      > I agree with Tom!
                      >
                      > 73,
                      > Bruce,
                      > K2BET
                      > --------------
                      >
                      > On 5/13/2011 5:41 AM, Thomas Bewick wrote:
                      > >
                      > > Chester,
                      > >
                      > > I would highly recommend you go for that licence!
                      > > As an experienced SWL and SoftRock Kit builder you would have no
                      > > trouble studying and passing the exams and it will add so much more to
                      > > your radio experience and fun.
                      > >
                      > > I would recommend finding a local HAM club searching the internet and
                      > > seeing if they give the tests and may even have some license classes
                      > > available. And of course either the ARRL or Gordon West license
                      > > manuals are a necessity,.
                      > >
                      > > Blessings to you in your endeavors,
                      > > 73
                      > > Tom
                      > > N2BEW
                    • Bruce Tanner
                      Christer, if you have a full wind on your toroids you can certainly accomplish the task of getting the Ham ticket ! Good luck! ;) bet
                      Message 11 of 22 , May 15, 2011
                      • 0 Attachment
                        Christer, if you have a full wind on your  toroids you can certainly accomplish the task of getting the Ham 'ticket'! Good luck! ;)

                        bet
                        ---

                        On 5/15/2011 6:32 AM, janchristerlarsson wrote:
                         

                        Thank's for the encouragement!

                        I cannot decide what is most fun!

                        I am now exploring the SDR hw's, the SDR software designs, listening to all the bands, digital modes etc.

                        I even enjoy winding toroids...

                        Christer

                        --- In softrock40@yahoogroups.com, Bruce Tanner <bet110@...> wrote:
                        >
                        > I agree with Tom!
                        >
                        > 73,
                        > Bruce,
                        > K2BET
                        > --------------
                        >
                        > On 5/13/2011 5:41 AM, Thomas Bewick wrote:
                        > >
                        > > Chester,
                        > >
                        > > I would highly recommend you go for that licence!
                        > > As an experienced SWL and SoftRock Kit builder you would have no
                        > > trouble studying and passing the exams and it will add so much more to
                        > > your radio experience and fun.
                        > >
                        > > I would recommend finding a local HAM club searching the internet and
                        > > seeing if they give the tests and may even have some license classes
                        > > available. And of course either the ARRL or Gordon West license
                        > > manuals are a necessity,.
                        > >
                        > > Blessings to you in your endeavors,
                        > > 73
                        > > Tom
                        > > N2BEW



                        __________ Information from ESET Smart Security, version of virus signature database 6123 (20110515) __________

                        The message was checked by ESET Smart Security.

                        http://www.eset.com
                      • ve3mic
                        Right you are Alan! In my haste, I neglected to look at the power supply schematics before I sent my original post regarding the DC-DC converter. No 12VDC is
                        Message 12 of 22 , May 30, 2011
                        • 0 Attachment
                          Right you are Alan!

                          In my haste, I neglected to look at the power supply schematics before I sent my original post regarding the DC-DC converter. No 12VDC is required at all, since that 12VDC supply is immediately regulated down to 5V. And correct again, the Si570 is powered from the USBus.

                          I may try adding a "filtered USB powered" feed once my kit is finished.

                          Thanks all who responded to my post.
                          73 de Mike, VE3MIC


                          --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
                          >
                          >
                          > ----- Original Message -----
                          > Subject: RE: [softrock40] Re: DC-DC converter for Ensemble RX II
                          >
                          >
                          > >The current on the 5v RX side (after the regulator) can not be more than a
                          > >few milliamps
                          >
                          > Yes, I was forgetting the Si570 is fed directly from the USB power.
                          >
                          > As Roger said Tony posted his method
                          > <http://groups.yahoo.com/group/softrock40/message/54144> He did not mention
                          > the method used in the V4 Softrock.
                          >
                          > 73 Alan G4ZFQ
                          >
                        • jor
                          Hi Mike, Dan Taylou has design a swticher power supply for the Norcal 2030 stransceiver. Think about the noise in and output must be well filterd and the
                          Message 13 of 22 , May 31, 2011
                          • 0 Attachment
                            Hi Mike,

                            Dan Taylou has design a swticher power supply for the Norcal 2030 stransceiver.

                            Think about the noise in and output must be well filterd and the electronis screend in a tin box.
                            Also LINEAR has switchers IC for low noise.

                            As far as i now the max output from the USB port is 500 mA and with Lap-Tops may be les.
                            See in my file " PE1KTH SDR AND SOUNDCART INFO"

                            73' Joris PE1KTH



                            --- In softrock40@yahoogroups.com, "ve3mic" <ve3mic@...> wrote:
                            >
                            > Right you are Alan!
                            >
                            > In my haste, I neglected to look at the power supply schematics before I sent my original post regarding the DC-DC converter. No 12VDC is required at all, since that 12VDC supply is immediately regulated down to 5V. And correct again, the Si570 is powered from the USBus.
                            >
                            > I may try adding a "filtered USB powered" feed once my kit is finished.
                            >
                            > Thanks all who responded to my post.
                            > 73 de Mike, VE3MIC
                            >
                            >
                            > --- In softrock40@yahoogroups.com, "Alan" <alan4alan@> wrote:
                            > >
                            > >
                            > > ----- Original Message -----
                            > > Subject: RE: [softrock40] Re: DC-DC converter for Ensemble RX II
                            > >
                            > >
                            > > >The current on the 5v RX side (after the regulator) can not be more than a
                            > > >few milliamps
                            > >
                            > > Yes, I was forgetting the Si570 is fed directly from the USB power.
                            > >
                            > > As Roger said Tony posted his method
                            > > <http://groups.yahoo.com/group/softrock40/message/54144> He did not mention
                            > > the method used in the V4 Softrock.
                            > >
                            > > 73 Alan G4ZFQ
                            > >
                            >
                          • vbifyz
                            Yesterday I have tried connecting the USB power and ground to the analog power and ground in my Ensemble II RX. I used a small ferrite toroid with about 10
                            Message 14 of 22 , May 31, 2011
                            • 0 Attachment
                              Yesterday I have tried connecting the USB power and ground to the analog power and ground in my Ensemble II RX. I used a small ferrite toroid with about 10 turns of 26AWG pair (+5 and ground on 2 wires wound together) for RF noise suppression.
                              I didn't see any additional RF noise, but the central peak became prominent (60Hz and about 10-15 harmonics on each side). This is a classic ground loop. The only way break the ground loop in this configuration is to add isolation transformers to the audio output. I may try this next weekend.

                              73, Mike

                              --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
                              >
                              >
                              > ----- Original Message -----
                              > Subject: [softrock40] DC-DC converter for Ensemble RX II
                              >
                              >
                              > I'm not sure anyone can predict if you will be troubled by USB noise. I
                              > tried something like this, a quick check showed no ill effects but I did not
                              > make it permanent.
                              >
                              > 73 Alan G4ZFQ
                              >
                            • Alan
                              ... Subject: [softrock40] Re: DC-DC converter for Ensemble RX II ... It is not the only way. A ground loop is due to two, or more connections between the
                              Message 15 of 22 , Jun 1, 2011
                              • 0 Attachment
                                ----- Original Message -----
                                Subject: [softrock40] Re: DC-DC converter for Ensemble RX II


                                > Yesterday I have tried connecting the USB power and ground to the analog
                                > power and ground in my Ensemble II RX. I used a small ferrite toroid with
                                > about 10 turns of 26AWG pair (+5 and ground on 2 wires wound together) for
                                > RF noise suppression.
                                > I didn't see any additional RF noise, but the central peak became
                                > prominent (60Hz and about 10-15 harmonics on each side). This is a classic
                                > ground loop. The only way break the ground loop in this configuration is
                                > to add isolation transformers to the audio output.

                                It is not the only way.
                                A ground loop is due to two, or more connections between the Softrock and
                                computer.
                                It is always possible to make this just one, difficult maybe, if you have
                                not made it easy to experiment with removing the grounds.
                                Start by breaking the ground in the audio lead.
                                The best results I've had were by bonding everything to a good ground. I
                                then found that introducing a ground loop made no difference.

                                73 Alan G4ZFQ
                              • n6gn
                                This is just a note to the list to say that I had good luck with building a DC-DC converter to generate 12 VDC from the USB derived 4.3 VDC on a QRP2000 Si570
                                Message 16 of 22 , Jun 3, 2011
                                • 0 Attachment
                                  This is just a note to the list to say that I had good luck with building a DC-DC converter to generate 12 VDC from the USB derived 4.3 VDC on a QRP2000 Si570 synthesizer and used as LO for a slightly modified Ensemble II RX.

                                  The synthesizer is essentially a stand-alone version of those in the SoftRocks. I got mine from KM5H. Since I had both the synthesizer and an Ensemble RX II that was xtal'd on 40M, I thought it would be handy to use the synth and to power it all from the single USB connection. The result requires only antenna input, USB connection and I/Q cable.

                                  In addition, I dropped R16 to ~8K ohms so the 0 dBm from the LVDS of the synth would drive it and also widened the Ensemble RX input BPF to become mainly a high pass filter with ~ 10 MHz corner. To do that I removed C4, made C3 162 pf and made L4 only 9 turns instead of the 34 it previously had as 40M filter.

                                  The results are better than I thought they would be. Though I built the DC-DC converter with SMT parts (dead bug mounted) keeping the total clustered and with short connections, I figured that there might be serious problems from the 500 kHz oscillator in the LT1372. As it turned out, there really weren't any particular problems even down on 160 and 80M (where the filter was rolled off some but still letting some signal through).

                                  If anyone else wants to do this, all I did was implement the example circuit from the data. See http://www.linear.com/product/LT1372.

                                  I'm now using it with an ASUS netbook and the package makes a portable all band receiver about the size of a sheet of paper.
                                  I think the Ensemble/synth pulls ~ 200 mA from the 5 VDC on the USB port, but I didn't actually measure current into the finished unit.

                                  Glenn n6gn
                                • Alan Campbell
                                  OK, time for me to expose my ignorance again... Why insist on 12V output? Specifically, I m looking at the schematic for the Ensemble II and the only chip
                                  Message 17 of 22 , Jun 5, 2011
                                  • 0 Attachment
                                    OK, time for me to expose my ignorance again... Why insist on 12V output?

                                    Specifically, I'm looking at the schematic for the Ensemble II and the only chip using the +12V is the 78L05 - which then spits out +5V. At up to 100mA (by datasheet).
                                    Anything over 7-8V is wasted in the 78L05 and can even cause thermal shutdown.

                                    I read one web page that mentioned using a 9V battery to run the Ensemble II.  Looking at the circuit for the LT1372, I'd suggest dropping R1 for a lower output voltage would be more efficient.
                                    Less power produced, less wasted.

                                    Still, as long as it works, that's the main thing. Experimenting can be a lot of fun.

                                    -- Alan Campbell
                                       PF95ie


                                    From: n6gn <n6gn@...>
                                    To: softrock40@yahoogroups.com
                                    Sent: Saturday, 4 June 2011 1:53 PM
                                    Subject: [softrock40] Re: DC-DC converter for Ensemble RX II

                                     


                                    This is just a note to the list to say that I had good luck with building a DC-DC converter to generate 12 VDC from the USB derived 4.3 VDC on a QRP2000 Si570 synthesizer and used as LO for a slightly modified Ensemble II RX.

                                    The synthesizer is essentially a stand-alone version of those in the SoftRocks. I got mine from KM5H. Since I had both the synthesizer and an Ensemble RX II that was xtal'd on 40M, I thought it would be handy to use the synth and to power it all from the single USB connection. The result requires only antenna input, USB connection and I/Q cable.

                                    In addition, I dropped R16 to ~8K ohms so the 0 dBm from the LVDS of the synth would drive it and also widened the Ensemble RX input BPF to become mainly a high pass filter with ~ 10 MHz corner. To do that I removed C4, made C3 162 pf and made L4 only 9 turns instead of the 34 it previously had as 40M filter.

                                    The results are better than I thought they would be. Though I built the DC-DC converter with SMT parts (dead bug mounted) keeping the total clustered and with short connections, I figured that there might be serious problems from the 500 kHz oscillator in the LT1372. As it turned out, there really weren't any particular problems even down on 160 and 80M (where the filter was rolled off some but still letting some signal through).

                                    If anyone else wants to do this, all I did was implement the example circuit from the data. See http://www.linear.com/product/LT1372.

                                    I'm now using it with an ASUS netbook and the package makes a portable all band receiver about the size of a sheet of paper.
                                    I think the Ensemble/synth pulls ~ 200 mA from the 5 VDC on the USB port, but I didn't actually measure current into the finished unit.

                                    Glenn n6gn



                                  • n6gn
                                    Alan, Probably a good point in general. 12 VDC isn t particularly magic. However it does potentially give a bit more headroom before distortion in the OpAmps.
                                    Message 18 of 22 , Jun 6, 2011
                                    • 0 Attachment
                                      Alan,
                                      Probably a good point in general. 12 VDC isn't particularly magic. However it does potentially give a bit more headroom before distortion in the OpAmps. I'm surprised that they aren't run from it instead of the 5 VDC of the SR Ensemble RX design. Maybe I've missed something obvious though.

                                      Also, I don't know that there is a linear correlation between output voltage on the switching regulator and overall efficiency. At least, I'd suspect for very low outputs, even with all else equal (which it never is!) that diode drop in the switcher would begun to hurt.

                                      Still, if someone is looking for alternative ways of powering a SoftRock/Si570 combination there's no requirement to provide 12V.

                                      I think the most useful thing I found is that switching regulator hash needn't be a severe problem. I suspect that the switched capacitor DC-DC converter solutions - which generally are limited to 2x voltage- might work just as well as the inductive switcher I used.

                                      I'd say the good news is that it isn't difficult to combine existing SR hardware/synthesizers to make a small, portable, all-mode, general coverage receiver that has decent performance very inexpensively.

                                      Best,
                                      Glenn n6gn

                                      > OK, time for me to expose my ignorance again... Why insist on 12V output?
                                      >
                                    • The Silver Fox
                                      Just for reference: I ve run my softrocks with 9V DC power for a long time without any noticeable negative effects but I ll admit that I ve not pushed them to
                                      Message 19 of 22 , Jun 6, 2011
                                      • 0 Attachment

                                        Just for reference:  I’ve run my softrocks with 9V DC power for a long time without any noticeable negative effects but I’ll admit that I’ve not pushed them to the limit on transmit.

                                        73’s

                                        Alan – W6ARH

                                         

                                        From: softrock40@yahoogroups.com [mailto:softrock40@yahoogroups.com] On Behalf Of n6gn
                                        Sent: Monday, June 06, 2011 8:10 AM
                                        To: softrock40@yahoogroups.com
                                        Subject: [softrock40] Re: DC-DC converter for Ensemble RX II

                                         

                                         



                                        Alan,
                                        Probably a good point in general. 12 VDC isn't particularly magic. However it does potentially give a bit more headroom before distortion in the OpAmps. I'm surprised that they aren't run from it instead of the 5 VDC of the SR Ensemble RX design. Maybe I've missed something obvious though.

                                        Also, I don't know that there is a linear correlation between output voltage on the switching regulator and overall efficiency. At least, I'd suspect for very low outputs, even with all else equal (which it never is!) that diode drop in the switcher would begun to hurt.

                                        Still, if someone is looking for alternative ways of powering a SoftRock/Si570 combination there's no requirement to provide 12V.

                                        I think the most useful thing I found is that switching regulator hash needn't be a severe problem. I suspect that the switched capacitor DC-DC converter solutions - which generally are limited to 2x voltage- might work just as well as the inductive switcher I used.

                                        I'd say the good news is that it isn't difficult to combine existing SR hardware/synthesizers to make a small, portable, all-mode, general coverage receiver that has decent performance very inexpensively.

                                        Best,
                                        Glenn n6gn

                                        > OK, time for me to expose my ignorance again... Why insist on 12V output?
                                        >

                                      Your message has been successfully submitted and would be delivered to recipients shortly.