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1. 07:54 AM - Re: Re: Dan's Jabiru 3300 Wiring Schematic (Robert L. Nuckolls, III)
2. 10:00 AM - Re: Dan's Jabiru 3300 Wiring Schematic (user9253)
Message 1
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| Subject: | Re: Dan's Jabiru 3300 Wiring Schematic |
At 09:46 PM 8/27/2009, you wrote:
>
>I have taken a portion of Dan's schematic that pertains to the
>dynamo, regulator, and tachometer and simplified it in an attempt to
>better understand it. I moved the bridge rectifier outside of the
>regulator. And I added one more diode in series with the tach so
>that the tach only sees half of the dynamo waveform. By adding this
>extra diode, I believe that the tach will see the same signal
>whether the alternator relay is pulled in or not, since the tach is
>connected in parallel with the dynamo through two diodes. The
>dynamo frequency is dependent upon the engine speed since it is
>mounted onto the flywheel. The output voltage will vary depending
>of the state of the disconnect relay and aircraft load. However,
>the voltage should not affect the tach unless it drops below the
>minimum (2.5 to 5 volts) required.
> Bob, what do you think? Will Dan's tach work as connected in
> his schematic if a diode is added in series with it? Or do I have
> it all wrong? And that could be, because I do not know what is
> inside of the regulator case.
Good question. You know what you do not know.
Similarly, I know that I know nothing about
the functional requirements for any particular
tachometer. It's unwise for me to suggest that
modification of the tachometer's signal path (by
breaking one AC lead from the alternator) will
not have a deleterious effect on its performance.
You're on the right track for the crafting an
experiment and verifying the significance of
results before you fly the airplane. But the
"2.5 to 5.0 volts minimum" requirement does
not speak to distortions of waveform.
I'm in CA right now sorting out the simple-ideas
for the outcome of an experiment that was not conducted
to a useful and significant conclusion before
flight.
The short answer to your question is hook it
up, give it a try. It wouldn't hurt to take some
'scope waveform data on the relay-open and
relay-closed conditions. Then share those pictures
with the the folks who built the tach. It's
a sure bet that they did not anticipate a need
to remain functional with one of the AC power
leads from the dynamo disconnected from the
rectifier/regulator.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
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Message 2
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| Subject: | Re: Dan's Jabiru 3300 Wiring Schematic |
Thanks for the reply Bob. Unfortunately I live a long way from Dan. Perhaps he
will let us know how he connected his tachometer to make it work to his satisfaction.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=260233#260233
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