[sdiy] A little OT, Begging a hand

[Veronica Merryfield]

On 2011-02-08, at 5:14 AM, Jerry Gray-Eskue wrote:

> If I am reading this corectly, what you really want to know is the value of the resistors but for some reason cannot measure them directly?  

Correct. My access points are V1, V2 and Vout.

> Where did the values (R1+R2+R3=K, about 600 ohms etc.) come from?

Property of the sensor.

> << For reference, this is the equivalent circuit for a sensor I am working with on a music controller project.>>
> 
> If this is a sensor, it will be something other than a fixed value resistor network, is that what you meant by
> <<R4 and R5 vary between about 1K and 500K>> ?

Correct. R1, R2, R3, R4, R5, R6 and R7 all vary, R7=R2 and R6=R1

> 
> 
> 
> ----- Original Message ----- From: "Veronica Merryfield" <veronica.merryfield at shaw.ca>
> To: "synth DIY" <synth-diy at dropmix.xs4all.nl>
> Sent: Tuesday, February 08, 2011 12:50 AM
> Subject: [sdiy] A little OT, Begging a hand
> 
> 
>> I wonder if anyone might be able to help me out on what I was hoping was a simple problem.
>> 
>> I have the following resistor network (ascii art follows so you'll need a fixed pitch font selected)
>> 
>> V1
>> |
>> \
>> / R1
>> \
>> /
>> |    R4        R6
>> |--/\/\/\----/\/\/\----- Vout
>> |          |         |
>> \          \         \
>> / R2       / R7      / R8
>> \          \         \
>> /          /         /
>> |    R5    |         |
>> |--/\/\/\--          |
>> |                    V3
>> \
>> / R3
>> \
>> /
>> |
>> V2
>> 
>> I can set each of V1, V2 and V3 to either +Ve, GND or OC independently, although not all combinations are useful, and I can measure Vout. R1+R2+R3=K, about 600 ohms. R1=R6 and R2=R7, R4 and R5 vary between about 1K and 500K and R8 is fixed at 2K2 although this can be changed.
>> 
>> I want to set a number of input combinations and measure Vout from each in the hope that I can determine R1, R2, R3, R4 and R5 with some simultaneous equations.
>> 
>> My attempts have been a bit of a failure and I think I am missing something so I was hoping someone here might be able to help me.
>> 
>> For reference, this is the equivalent circuit for a sensor I am working with on a music controller project.
>> 
>> Veronica
>> 
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>> Synth-diy at dropmix.xs4all.nl
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy 
> 
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