nuckollsr(at)cox.net Guest
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Posted: Wed Mar 01, 2006 6:39 am Post subject: Ground Power circuit diagram query & suggestion |
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At 01:23 AM 3/1/2006 +0000, you wrote:
Quote: |
Hi Bob,
I don't understand the need for a push-to-test lamp in your Low Cost
Ground Power circuit (rev C 07/21/05).
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Quote: | Surely it would provide a more useful function if it were a regular lamp
directly connected to ground, therefore providing either;
(a) a warning of presence of a ground power source, or;
(b) a warning that the switch/breaker for ground power contactor is
still closed (where the ground power contactor is held closed by ship's
battery). This function seems important since the contactor takes
nearly a Amp to maintain.
Either of those without having to press a button to find out. Since you
need some ground power-side volts to light it anyway, it will normally
be off AND "un-testable".
Better still, you could use a bi-colour LED, with GREEN for correct
polarity and RED for inverted (help save a contactor diode if you
reverse-connect the leads to the 4x4)
My 1st post & just getting my head round all the issues, so excuse me if
I missed something obvious. Looking forward to the book arriving
tomorrow.
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Certainly there are variations on the theme that provide
alternative flavors of functionality. The architecture cited
was crafted based on a customer's request for a hurry up
kit for a ground power jack, my experience with ground
power on aircraft and what was in my inventory of components
at the time.
You can certainly modify as you see fit. The important thing
is that you UNDERSTAND how the end product is going to work
and that features and performance are acceptable to you
as the systems designer and user.
Bob . . .
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