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fuel gage/sender compatability

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ashleysc(at)broadstripe.n
Guest

Posted: Thu Apr 27, 2017 11:53 am Post subject: fuel gage/sender compatability

Calling all Electronics Wizards;

I have a fuel sender installed in each wing that ranges from 10 ohms full to 73 ohms empty. These are hard to get to, and I don't want to change them out unless necessary. I have a dual fuel gauge capable of reading the fuel depth in two tanks. It wants 40 ohms full and 240 ohms empty. Is there some type of "resistance multiplier circuit that I could install between sender and gauge so that they can be used together?

Cheers!   Stu.

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nuckolls.bob(at)aeroelect
Guest

Posted: Thu Apr 27, 2017 3:04 pm Post subject: fuel gage/sender compatability

At 02:52 PM 4/27/2017, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: ashleysc(at)broadstripe.net



 

 Calling all Electronics Wizards;

 I have a fuel sender installed in each wing that ranges from 10 ohms full to 73 ohms empty. These are hard to get to, and I don't want to change them out unless necessary. I have a dual fuel gauge capable of reading the fuel depth in two tanks. It wants 40 ohms full and 240 ohms empty. Is there some type of "resistance multiplier circuit that I could install between sender and gauge so that they can be used together?

 Cheers!   Stu. 	


   Yeah  . . . sort of. It's called an 'operational

   amplifier'. A versatile device that can 'watch'

   your 10/73 transducer and convert it into

   a VOLTAGE that mimics the voltages expected across

   the 40/240 transducer when wired to the mated

   instrument.



   What we need is a measure of the transducer

   bias current that comes out of the instrument when

   terminated with a 40 ohm resistor, and then with

   a 240 ohm resistor.



   Knowing those values will allow us to calculate the

   resistors that tell the op-amp how to apply its

   magic. This technique will set the 'endpoints'

   for the instrument . . . calibration at empty

   and full.  Accuracy of the readings between

   these values will have to be deduced by filling

   the tanks with the ship in a pitch attitude

   consistent with level flight.



   However, even without calibration, they'll be

   sufficiently accurate to run your pucker factor

   up as the needles drop below 1/4 full.



 

 

   Bob . . .

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ashleysc(at)broadstripe.n
Guest

Posted: Thu Apr 27, 2017 5:53 pm Post subject: fuel gage/sender compatability

Hi Bob;

Thanks for your help. I will get 40 and 240 ohm resistors, make the test, and get back to you with the results via this mode.

Cheers!   Stu.

From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>

To: aeroelectric-list(at)matronics.com

Sent: Thursday, April 27, 2017 4:03:16 PM

Subject: Re: AeroElectric-List: fuel gage/sender compatability

At 02:52 PM 4/27/2017, you wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: ashleysc(at)broadstripe.net

 Calling all Electronics Wizards;

 I have a fuel sender installed in each wing that ranges from 10 ohms full to 73 ohms empty. These are hard to get to, and I don't want to change them out unless necessary. I have a dual fuel gauge capable of reading the fuel depth in two tanks. It wants 40 ohms full and 240 ohms empty. Is there some type of "resistance multiplier circuit that I could install between sender and gauge so that they can be used together?

 Cheers!   Stu. 	

   Yeah  . . . sort of. It's called an 'operational

   amplifier'. A versatile device that can 'watch'

   your 10/73 transducer and convert it into

   a VOLTAGE that mimics the voltages expected across

   the 40/240 transducer when wired to the mated

   instrument.

  What we need is a measure of the transducer

   bias current that comes out of the instrument when

   terminated with a 40 ohm resistor, and then with

   a 240 ohm resistor.

  Knowing those values will allow us to calculate the

   resistors that tell the op-amp how to apply its

   magic. This technique will set the 'endpoints'

   for the instrument . . . calibration at empty

   and full.  Accuracy of the readings between

   these values will have to be deduced by filling

   the tanks with the ship in a pitch attitude

   consistent with level flight.

  However, even without calibration, they'll be

   sufficiently accurate to run your pucker factor

   up as the needles drop below 1/4 full.

  Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

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