nuckolls.bob(at)aeroelect Guest
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Posted: Fri May 11, 2012 5:20 pm Post subject: connect 1-5 volt fuel level sender to legacy type fuel gag |
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At 03:48 PM 5/11/2012, you wrote:
Quote: |
Hi Bob,
I'm toying with the idea of installing Electronics International's
new magnetic fuel level senders, that output 1-5 volts from empty to
full, to interface with a JPI 930 or similar.
However, I'd like to continue to make the legacy 12 volt Wheatstone
bridge style needle gage work...
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What are the characteristics of the instrument?
Current full scale? It's pretty easy to craft
an op-amp signal conditioner that will apply the
necessary gain and offset to spread the 1-5 volt
signal over the legacy instrument's scale.
These tend to be 'beefy' instruments of perhaps
10 ma full scale. The signal conditioner would have
to be vetted for this much sink or source current.
If you can get full scale current value for me
along with the old resistance sender's empty-full
span I can sketch a circuit and propose parts.
On way to do it in the airplane is hook a rheostat
up to emulate the old sender. Adjust the rheostat
first for FULL indication, measure voltage across
the rheostat before disconnecting it to measure
its resistance. Repeat for 1/2 and empty. The
only reason you need reading at 1/2 is to verify
that the instrument is reasonably linear.
Bob . . .
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