Now that we finally get to see what it is that You are trying to do .......
The next question is,
why are You using 3- Op-Amps instead of the special Circular Resistor Arrangement ?
and,
Are You using the 3-Phase "Motor"/ Indicator exactly as pictured ?
Or,
is there some other similar device (Indicator) that You wish to Power ?
Are You building your own DIY "version" of this device ?
In other words, do You actually need Plus and Minus 24-Volts for a particular reason, and
will the Resistances of the Windings still be ~410-Ohms ?

What is the entire Signal-Chain ?
What will this device be Indicating the position of ?
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Simple answer is -It's hard to get these resistance winding repaired If winding is worn out on open. So like to replace that resistance winding system.

 

What kind of magnetic encoder do you plan to use ? If you mean an AC synchro transmitter then you will have to use synchronus rectification to convert the three AC outputs to DC signals with varying output and polarity. In the past I have used the DC selsyn systems for antenna position indicators but I used the original type of resistive encoder.

Les.

It's DC resistance readout you can replace with Standard potinometer but the indicator need 3 inputs to move the dial

 

Hi Dave,
How are you going to calibrate the Scales of the 3 pots.?
and keep them in Sync.

BTW: The load on the OPA's is Inductive!

 

"" It's hard to get these resistance winding repaired If winding is worn out on open.
So like to replace that resistance winding system "".
This doesn't address what type of mechanical device You are working with.
What operates the existing special Rheostat ?
How many degrees of Rotation does it have to have ?
Is it set-up for an unlimited number of turns ?
How about some pictures ?
Most likely, it will have to be replaced by an Optical-Rotary-Encoder.
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If the actual input is 6 V then this should work:
View attachment 244949R2 and R3 can be other values as long as the ratio of R2 to R3 is 3 to 1.

Thanks for you input DC . Will use 2.7 reference input voltage . And correct the feedback resistance.

 

Take a look at parts by Melexis.