OxAero wrote:

The problem was that the large regulator couldn't handle the start up
load from the transponder. So, my quick fix was to bypass that
regulator with the second switch. I expect to revisit the project some
day and finish it properly.

If you are using a transponder like the Becker ATC 4401, the bypass is
the best setup. The Becker, like many other modern transponders and
radios, has a wide range input voltage regulator (9-32 volts for the
Becker), so regulating it's input voltage has no advantage. As you
discovered, it may even prevent the equipment from working properly, as
it is designed to operate from a battery, not a regulated supply.

I suggest you determine exactly which instrument(s) really benefit from
input voltage regulation and put only those on the regulator. Most of
the newer equipment we use was specifically designed for battery use, so
adding a regulator just increases the things that can fail.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org