[aprssig] Fossil-fuel-free-Fieldday Fun

Robert Bruninga bruninga at usna.edu
Thu Jun 11 10:12:04 EDT 2015

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.

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.

By upconverting to 330 VDC there are several advantages:

1)      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

2)      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.

3)      You can parallel as many cars as you like at 330 VDC for
distributed energy

4)      10 solar panels in series can provide 330 VDC at 7 amps (over 2 kW)

5)      Or you can put microinverters ($125) on each solar panel to
gernerate the 120vac (into 330VDC) for distributed power

The disadvantage is re-educating ham operators about high voltage DC safety.

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.

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…

I have done that over 3000’ using nothing but one #24 wire and Ground.
See  http://aprs.org/aprs-swer.html

But for Fieldday distances, better to avoid the ground loop and simply run
two-conductor zip cord or other convenient wire.

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

Bob, Wb4APR
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