[amsat-bb] Linear vs. switching and HV DC

Bob Bruninga bruninga at usna.edu
Fri Feb 18 11:54:43 PST 2011

> Is there a Amsat BB favorite between switching and linear [power

I won't speak to noise, which is the only potential issue with switching
power supplies, but other than that, I am writing an article for QST that
points out how the world of power and emergency power has changed
drastically over the last decades.  Entirely due to switching power supplies
and regulators:

1) A 90% reduction in size and weight
2) Laptop supplies that can supply 12v at 5 to 10 amps
3) Universal inputs 115V to 240V AC
4) * also run on 150 to 330 VDC
5) Hybrids and Electric Vehicles have Kilowatts of 150 to 330 VDC available
6) Home grid-tie solar has Kilowatts of high voltage DC available
7) 12VDC to 120VAC inverters are now sine and modified sine at 90%+
8) * These internally run on 200 VDC or so. Easy to run great distances on
small wire if you run them directly on HV DC derived from your Hybrid or

CONS: with today's litigious society and general ignorance (compared to the
vacuum tube days when even cub-scouts built 2 tube radios with High
Voltage), it is doubtful that QST will publish the article.  They have
rejected it before, but I keep whittling away at the details.

Bottom line, is that high efficiency high voltage DC is everywhere and
because everything runs on switching power supplies that run internally on
HV DC and regulators that accept a wide range of input, then HV DC could be
the new universal power source.

Problem is, Hybrid and EV MFR's are not going to provide access to HV DC
willingly due to safety an liability issues.  Same for Solar installers....
Same for QST.

But you can get some of what I am writing about on this page: 

For example, buried in a Camry Hybrid is a nice compact stand-alone 14 volt
100 AMP DC/DC supply.  Input can be 200 to 350 volts DC (which you can get
from 120V or 240VAC with just some diodes)..  Problem is, it is bolted to
the $1000 salvage battery and the salvage guys won't sell it separately.

The Prius 100amp 14v supply is integrated into the huge drivetrain inverter
and inseparable from that $3000 unit (salvage cost).

As we electrify transportation and anyone with good sun goes solar, HV DC
will be something Hams will be getting used to again.

Bob, Wb4APR

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