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    <p>In addition to that, when using linear regulators with LEDs,
      regulate current rather than voltage. The reason for this is that
      these LEDs get quite hot during operation, and that probably
      lowers their threshold voltage noticeably, so that there may be a
      risk of thermal runaway. <br>
    </p>
    <p>Kind regards,<br>
    </p>
    <p>Helmut.
    </p>
    <pre class="moz-signature" cols="72">
On 26/06/2019 8:15 PM, Trevor Wignall wrote:
</pre>
    <blockquote type="cite"
cite="mid:CAJKUhDPVjutqPybKDCPk7jjoxAuuZNC_M2bspYbOvwxvmjLvmw@mail.gmail.com">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div dir="ltr">The LEDs themselves should not be causing
        interference. What is probably causing the interference is the
        buck mode converter which takes the higher battery voltage and
        reduces it to the LED's voltage while increasing the current, to
        achieve relatively high efficiencies. These use inductors and
        rapidly switching transistors. If you can put up with higher
        battery current drains and some localised heating, then you can
        use linear regulators which don't have these switching elements
        and therefore don't radiate.
        <div>Ferrite beads can be effective at keeping RF where it
          belongs - the tighter around the wires and the longer the
          better. If you are prepared to solder onto the circuit board,
          some strategically placed low value (100s of pF) capacitors
          can help. (It helps to know the transmitter frequency to
          choose the best values for the task.)</div>
        <div>Not all LED lights even use regulators. Some of the cheaper
          ones with multiple small LEDs just have a series resistor, and
          these should also be quiet.</div>
        <div>I hope this helps</div>
        <div>Trevor</div>
        <div><br>
        </div>
      </div>
      <br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">On Wed, Jun 26, 2019 at 10:43
          AM Bevin Brett <<a href="mailto:bevin_brett@hotmail.com"
            moz-do-not-send="true">bevin_brett@hotmail.com</a>>
          wrote:<br>
        </div>
        <blockquote class="gmail_quote" style="margin:0px 0px 0px
          0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
          <div>
            <div dir="auto">Talking to my daughter who is involved in
              kiwi conservation.  They track, find kiwi using small
              transmitters on the bird leg and the teams carry a
              directional receiver with About a one metre antenna
              <div dir="auto"><br>
              </div>
              <div dir="auto">But they can't use LED lights at night
                because of interference.  </div>
              <div dir="auto"><br>
              </div>
              <div dir="auto">How easy would it be to shield a normal
                commercial head lamp?</div>
              <div dir="auto"><br>
              </div>
              <div dir="auto">Wrap it in alfoil?  Small metal mesh? Mesh
                with some trivial circuit?</div>
            </div>
            <div class="gmail_extra"><br>
              <div class="gmail_quote">On Jun 17, 2019 11:00 PM, <a
                  href="mailto:chchrobotics-request@lists.ourshack.com"
                  target="_blank" moz-do-not-send="true">chchrobotics-request@lists.ourshack.com</a>
                wrote:<br type="attribution">
                <blockquote class="gmail-m_-4681944267343632738quote"
                  style="margin:0px 0px 0px 0.8ex;border-left:1px solid
                  rgb(204,204,204);padding-left:1ex">
                  <p dir="ltr">Send Chchrobotics mailing list
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                  <p dir="ltr">When replying, please edit your Subject
                    line so it is more specific<br>
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                  </p>
                  <p dir="ltr">Today's Topics:</p>
                  <p dir="ltr">   1. Sipeed MAix BiT for RISC-V AI+IoT -
                    Seeed Studio (Synco Reynders)<br>
                       2. Robotics Group meeting, Monday 17 June 2019,
                    630pm, 5 Idris<br>
                          Road (Mark Atherton)<br>
                  </p>
                  <p dir="ltr">----------------------------------------------------------------------</p>
                  <p dir="ltr">Message: 1<br>
                    Date: Mon, 17 Jun 2019 21:58:00 +1200<br>
                    From: Synco Reynders <<a
                      href="mailto:synco.reynders@gmail.com"
                      target="_blank" moz-do-not-send="true">synco.reynders@gmail.com</a>><br>
                    To: Christchurch Robotics <<a
                      href="mailto:chchrobotics@lists.linuxnut.co.nz"
                      target="_blank" moz-do-not-send="true">chchrobotics@lists.linuxnut.co.nz</a>><br>
                    Subject: [chbot] Sipeed MAix BiT for RISC-V AI+IoT -
                    Seeed Studio<br>
                    Message-ID:<br>
                    <CAKNOA8J=<a
                      href="mailto:UrmPOjVwfwNP2rSkEMrbngRt-6-cTCTMUUuk098ogg@mail.gmail.com"
                      target="_blank" moz-do-not-send="true">UrmPOjVwfwNP2rSkEMrbngRt-6-cTCTMUUuk098ogg@mail.gmail.com</a>><br>
                    Content-Type: text/plain; charset="utf-8"</p>
                  <p dir="ltr">Here is the link to where I bought the
                    board...<br>
                    <a
href="https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.seeedstudio.com%2FSipeed-MAix-BiT-for-RISC-V-AI-IoT-1-p-2873.html&amp;data=02%7C01%7C%7C9de3110e1bff46b5abc008d6f312f8d3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636963660150070012&amp;sdata=LhJuCO%2BfUC%2FicknxuIrv0qAXU8fsIgi8qLqWfAAKGqg%3D&amp;reserved=0"
                      target="_blank" moz-do-not-send="true">https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.seeedstudio.com%2FSipeed-MAix-BiT-for-RISC-V-AI-IoT-1-p-2873.html&amp;data=02%7C01%7C%7C9de3110e1bff46b5abc008d6f312f8d3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636963660150070012&amp;sdata=LhJuCO%2BfUC%2FicknxuIrv0qAXU8fsIgi8qLqWfAAKGqg%3D&amp;reserved=0</a></p>
                  <p dir="ltr">Data sheet for the K210<br>
                    <a
href="https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.google.com%2Furl%3Fsa%3Dt%26source%3Dweb%26rct%3Dj%26url%3Dhttps%3A%2F%2Fs3.cn-north-1.amazonaws.com.cn%2Fdl.kendryte.com%2Fdocuments%2Fkendryte_datasheet_20181011163248_en.pdf%26ved%3D2ahUKEwiW-PPrjPDiAhW96nMBHRBbAecQFjABegQIBxAB%26usg%3DAOvVaw3CVZJWXlKkFgXPVCf8L4Ts%26cshid%3D1560765344956&amp;data=02%7C01%7C%7C9de3110e1bff46b5abc008d6f312f8d3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636963660150070012&amp;sdata=YtKt%2FRVCAZVXedlQd9dOBnCe13RRwBaBAQrCjHelSu8%3D&amp;reserved=0"
                      target="_blank" moz-do-not-send="true">https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.google.com%2Furl%3Fsa%3Dt%26source%3Dweb%26rct%3Dj%26url%3Dhttps%3A%2F%2Fs3.cn-north-1.amazonaws.com.cn%2Fdl.kendryte.com%2Fdocuments%2Fkendryte_datasheet_20181011163248_en.pdf%26ved%3D2ahUKEwiW-PPrjPDiAhW96nMBHRBbAecQFjABegQIBxAB%26usg%3DAOvVaw3CVZJWXlKkFgXPVCf8L4Ts%26cshid%3D1560765344956&amp;data=02%7C01%7C%7C9de3110e1bff46b5abc008d6f312f8d3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636963660150070012&amp;sdata=YtKt%2FRVCAZVXedlQd9dOBnCe13RRwBaBAQrCjHelSu8%3D&amp;reserved=0</a><br>
                    -------------- next part --------------<br>
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                  <p dir="ltr">------------------------------</p>
                  <p dir="ltr">Message: 2<br>
                    Date: Mon, 17 Jun 2019 22:01:46 +1200<br>
                    From: Mark Atherton <<a
                      href="mailto:markaren1@xtra.co.nz" target="_blank"
                      moz-do-not-send="true">markaren1@xtra.co.nz</a>><br>
                    To: Christchurch Robotics <<a
                      href="mailto:chchrobotics@lists.linuxnut.co.nz"
                      target="_blank" moz-do-not-send="true">chchrobotics@lists.linuxnut.co.nz</a>><br>
                    Cc: Ian MacPherson <<a
                      href="mailto:ian@macpherson.gen.nz"
                      target="_blank" moz-do-not-send="true">ian@macpherson.gen.nz</a>>,
                    Rory Deans<br>
                    <<a href="mailto:rory1@xtra.co.nz"
                      target="_blank" moz-do-not-send="true">rory1@xtra.co.nz</a>><br>
                    Subject: [chbot] Robotics Group meeting, Monday 17
                    June 2019, 630pm, 5<br>
                    Idris Road<br>
                    Message-ID: <<a
                      href="mailto:6d4a8ac1-ad6c-fd28-1197-0fa30423c467@xtra.co.nz"
                      target="_blank" moz-do-not-send="true">6d4a8ac1-ad6c-fd28-1197-0fa30423c467@xtra.co.nz</a>><br>
                    Content-Type: text/plain; charset=utf-8;
                    format=flowed</p>
                  <p dir="ltr">Hello everyone,</p>
                  <p dir="ltr">Enthusiastic turnout with 20 attendees,
                    and lots of huddles-of <br>
                    tech-talk. $28 + change (in gold, and flat-money)
                    collected and <br>
                    transferred into the robotics loose-change jar (for
                    later banking).</p>
                  <p dir="ltr">Quick reminder: equipment donations are
                    welcome for the trading table,
                    <br>
                    but no products that are likely to be a disposal
                    burden such as <br>
                    printers, toner or similar. All sales from the
                    trading table should go <br>
                    into the brown box on the wall, and are directly for
                    the benefit of our <br>
                    host club, NZART Branch 05.</p>
                  <p dir="ltr">With thanks on behalf of the group,</p>
                  <p dir="ltr">Mark Atherton</p>
                  <p dir="ltr">============</p>
                  <p dir="ltr">Bevin brought along a soviet mechanical
                    calculator to talk about as well
                    <br>
                    as quite a photographic tour of one of his latest
                    mechanical calculator <br>
                    repair projects. Challenges include trying to drift
                    out a (possibly cold <br>
                    welded) taper pin. All in all, quite a mission…</p>
                  <p dir="ltr">William brought in a homemade intercom
                    using old telephones. Controller
                    <br>
                    is based around an Arduino Nano. Nice recycling
                    project.</p>
                  <p dir="ltr">Peter Harris talked about switched mode
                    power supplies, more <br>
                    specifically a battery management system for a
                    home-made wall-of-power. <br>
                    Quite a discussion ensued around how to spread load
                    across ten high <br>
                    voltage constant-current sources.</p>
                  <p dir="ltr">Synco talked about a tiny 64 bit image
                    recognition module. This US$21
                    <br>
                    module includes VGA camera, a small LCD display and
                    a CPU module. The <br>
                    main rub is that the CPU is RISC-V based running at
                    800MHz, with masses <br>
                    of I/O. The unit is configurable using a small FPGA,
                    and is running a <br>
                    port of a micro-python wrapper controlling an
                    embedded image-processing <br>
                    package.</p>
                  <p dir="ltr">Andy Gardner talked about his +-100kV
                    volt meter !<br>
                    <br>
                    <br>
                    <br>
                  </p>
                  <p dir="ltr">------------------------------</p>
                  <p dir="ltr">Subject: Digest Footer</p>
                  <p dir="ltr">_______________________________________________<br>
                    Chchrobotics mailing list<br>
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                    Meetings usually 3rd Monday each month. See <a
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                    for venue, directions and dates.<br>
                    Please edit your Subject line to reflect new
                    subjects. </p>
                  <p dir="ltr">------------------------------</p>
                  <p dir="ltr">End of Chchrobotics Digest, Vol 141,
                    Issue 4<br>
                    ********************************************<br>
                  </p>
                </blockquote>
              </div>
              <br>
            </div>
          </div>
          _______________________________________________<br>
          Chchrobotics mailing list <a
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          Meetings usually 3rd Monday each month. See <a
            href="http://kiwibots.org" rel="noreferrer" target="_blank"
            moz-do-not-send="true">http://kiwibots.org</a> for venue,
          directions and dates.<br>
          When replying, please edit your Subject line to reflect new
          subjects.</blockquote>
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      <pre class="moz-quote-pre" wrap="">_______________________________________________
Chchrobotics mailing list <a class="moz-txt-link-abbreviated" href="mailto:Chchrobotics@lists.ourshack.com">Chchrobotics@lists.ourshack.com</a>
<a class="moz-txt-link-freetext" href="https://lists.ourshack.com/mailman/listinfo/chchrobotics">https://lists.ourshack.com/mailman/listinfo/chchrobotics</a>
Mail Archives: <a class="moz-txt-link-freetext" href="http://lists.ourshack.com/pipermail/chchrobotics/">http://lists.ourshack.com/pipermail/chchrobotics/</a>
Meetings usually 3rd Monday each month. See <a class="moz-txt-link-freetext" href="http://kiwibots.org">http://kiwibots.org</a> for venue, directions and dates.
When replying, please edit your Subject line to reflect new subjects.</pre>
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