Today's Message Index:
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1. 01:29 PM - Re: IVO Prop Electronic CB report (Dennis & Anne Glaeser)
2. 06:45 PM - Amp Shunt Mounting Help Please (CardinalNSB@aol.com)
Message 1
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| Subject: | RE: IVO Prop Electronic CB report |
I corrected my wiring error and the circuit works perfectly! The amber LED
comes on when the current hits the limit (about 9A), and stays on as long as
the switch is held, but current to the motor drops to basically nothing
(measured with a clamp on ammeter on the ground lead). The IRFP3703 doesn't
even get noticeably warm (above the 90F ambient today!).
It will be next weekend at the earliest that I can get the Oscilloscope and
take the readings you described, but I would bet the readings will be as you
predict :-)
An implementation question: Are the values of R105 and R107 (the 1K
resistors in series with the LEDs) critical? The reason I ask is that I
have a couple of ready to mount LEDs that already have resistors built-in
for 12V use. I don't know what values they use for the resistors. My
suspicion is that they would work fine, but I don't want to spoil a
perfectly good recipe!
Thanks again!
Dennis
Message 2
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| Subject: | Amp Shunt Mounting Help Please |
(For a certified aircraft) I will be replacing my Cessna amp gauge with
the Electronics International Ammeter/Voltmeter, which is FAA approved for
my aircraft as a primary gauge replacement using a "shunt".
1. Should the shunt be mounted inside the cockpit or in the engine
compartment.
2. Should the shunt be firmly mounted to the firewall or other structure,
or is it ok to "freehang", it doesn't seem to be bigger than the turn
coordinator capacitor that just hangs in the harness.
3. The wires that go from the shunt to the instrument are hot whenever
the master switch is on. The installation manual recommends a 1 amp fuse on
each wire. What is the best fusing practice? inline fuse on each lead
next to the shunt? fuseable link? don't worry, the wire will burn out
somewhere before it causes problems? are there any shunts that incorporate a mini
atc fuse in its base?
4. For tidiness, I would like to use a single conductor shielded wire
using the shield as one of the shunt leads. Is there any reason this is not a
good idea? would twisting the leads in a drill mess up the accuracy?
5. Is there any reason I shouldn't take the voltage/power/light power off
of one of the ammeter leads (the one on the same side of the shunt as the
rest of the bus) to save running extra wire?
Thanks for the help, Skip S
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