<div dir="ltr"><div><div><div><div><div><div>Hi,<br><br></div>All this discussion reminded me of a funny story from my past. Hopefully no one is offended and if not interested please delete.<br><br></div>I was working as a broadcast engineer for a major TV broadcaster and we are covering a typical football game. This includes cameras all over the place, including one via really long cable in the parking lot ( yes now a days all done via RF, but we are talking the 80's ). The camera men had been advised to be careful of the cables as they are expensive and also have 300 VDC on them. That 300 VDC goes into a convertor at the base of the camera, to produce 12 volts to feed the camera.<br><br></div>Well one day, a very beautiful young lady had a dead battery and the camera operator decided to help out. Our first indication of problems was as his feed went dead ( disconnected the camera ). He then used two nails he found, to attach a set of booster cables and then put the nails into the two largest connector sockets. His logic was the camera runs on 12 volts, so therefore it must come in via the cable. The biggest sockets probably have the most power.<br><br></div>So back in the trailer, we finally get his feed back, after he plugs in the camera and we reset the power system, to have him showing the car on fire. <br><br></div>It was a good day. <br><br></div>Dale VE7PGB<br><div><div><br><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Jun 11, 2015 at 9:49 AM, Stanley Stone via aprssig <span dir="ltr"><<a href="mailto:aprssig@tapr.org" target="_blank">aprssig@tapr.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div>I love the idea--Bob definitely thinks out of the box. I’m sure someone told the Wright brothers that flying was dangerous, that you could get killed doing that. Instead of “that’s too dangerous…”, how about “How can we make this work and not kill ourselves?” </div><div><br></div><div>Stan, W4HIX<span class=""><br><div><br></div><br><blockquote type="cite">
<div class="gmail_quote">On Jun 11, 2015 7:13 AM, "Robert Bruninga via aprssig" <<a href="mailto:aprssig@tapr.org" target="_blank">aprssig@tapr.org</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div link="blue" vlink="purple" lang="EN-US"><div><p class="MsoNormal">Eventually we should get to a fossil-fuel-free fieldday. It is easy to avoid that stink-pot-foul smelling-polluting-noisey generator by just running some small conductor wire to every car parked at Fieldday. Parallel them all and without drawing more than 100W from each car, you can provide over a kW throughout fieldday just from batteries.</p><div> <br></div><p class="MsoNormal">Just plug in 100W cigarette lighter inverters into each car, add two caps and two diodes to double the 60 Hz 120v up to 330 VDC and distribute that to all the operating positions. Then just plug in standard SWITCHING power supplies wherever needed to the 330VDC and get all the 12v AMPS you need at each site.</p><div> <br></div><p class="MsoNormal">By upconverting to 330 VDC there are several advantages:</p><p><span>1)<span style="font:7.0pt "Times New Roman""> </span></span>Distribution wire size is only 1% of what it would need to be at 12v and only 10% of what it would be at 120v</p><p><span>2)<span style="font:7.0pt "Times New Roman""> </span></span>You can deliver over 1 kW via simple #18 zip cord over hundreds of feet and still only draw 3 amps, well below the rating of the wire.</p><p><span>3)<span style="font:7.0pt "Times New Roman""> </span></span>You can parallel as many cars as you like at 330 VDC for distributed energy</p><p><span>4)<span style="font:7.0pt "Times New Roman""> </span></span>10 solar panels in series can provide 330 VDC at 7 amps (over 2 kW) </p><p><span>5)<span style="font:7.0pt "Times New Roman""> </span></span>Or you can put microinverters ($125) on each solar panel to gernerate the 120vac (into 330VDC) for distributed power</p><div> <br></div><p class="MsoNormal">The disadvantage is re-educating ham operators about high voltage DC safety.</p><div> <br></div><p class="MsoNormal">After field day and crises at work, I hope to come up with a general idea and concept, and connectors, and safety features to make this a come-as-you-are way to make emergency field power not just for fielday but for everyday as-needed use.</p><div> <br></div><p class="MsoNormal">Remember, every HYBRID comes to Field Day with a few kWh of energy already at high voltage, and every electric car comes with 10 to 20 kWh of energy. But the easiest place to tap in, is still, the cigarette lighter at 12v and then upconvert to 330 VDC for distribution and then down convert back to 12v for universal usage at the station… </p><div> <br></div><p class="MsoNormal">I have done that over 3000’ using nothing but one #24 wire and Ground. See <a href="http://aprs.org/aprs-swer.html" target="_blank">http://aprs.org/aprs-swer.html</a> </p><p class="MsoNormal">But for Fieldday distances, better to avoid the ground loop and simply run two-conductor zip cord or other convenient wire.</p><div> <br></div><p class="MsoNormal">If you don’t understand HV DC, then ignore this and stay away. Remember even 8 year old cub scouts when I was a kid built HV Tube radios as a standard requirement with open wiring on mom’s spare breadboard… and none died…</p><div> <br></div><p class="MsoNormal">Bob, Wb4APR</p><div> <br></div></div></div>
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