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Reducing voltage divider and rheostat range

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neazoi

neazoi

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This is easy but I just need to make sure.

1. How do I reduce a 10k rheostat's range (potentiometer connected as a rheostat) to get a rheostat of 500 ohms?
2. How do I reduce a 10K potentiometer range to a 5k, so that the two edge pins (not the wiper) present a 5k to a source?

I guess in both cases some combination of parallel adding resistances could be done?
 

I guess in both cases some combination of parallel adding resistances could be done?
Click to expand...
Actually No. its depend on your needs,How do you need the pot to be? as a pot with variable terminal or just a fixed resistor?

If you add a 10 k parallel to a 10 k pot that is not exactly equivalent to a 5 k pot. It cant supply the current you want.

But if you connect the resistors from variable pin to other two fixed points, it will look like working but not at all linearly.
 
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    neazoi

    neazoi

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Venkadesh_M said:
Actually No. its depend on your needs,How do you need the pot to be? as a pot with variable terminal or just a fixed resistor?

If you add a 10 k parallel to a 10 k pot that is not exactly equivalent to a 5 k pot. It cant supply the current you want.

But if you connect the resistors from variable pin to other two fixed points, it will look like working but not at all linearly.
Click to expand...
It is not a fixed resistor divider, it is a potentiometer.
1. A voltage divider (volume control) that has to present an impedance of 5k to the source, but only a 10k pot is available to me. Current is not too important, as it will be low for audio.
2. A rheostat (used as a variable resistor only) that has to be adjusted from 0-500R, but only a 10k pot is available to me. Current is tiny as well.

Does the linearity degradation apply to the rheostat configuration also?
 

1. A voltage divider (volume control) that has to present an impedance of 5k to the source, but only a 10k pot is available to me. Current is not too important, as it will be low for audio.
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Then you can just put a 10k resistor in parallel, thats all. Here is no linearity degradation.

2. A rheostat (used as a variable resistor only) that has to be adjusted from 0-500R, but only a 10k pot is available to me. Current is tiny as well.
Click to expand...
It can be done in two ways

1, As 10k pot still can be varied from 0 - 500ohm(This range is also coming under 0 - 10k). But you cant limit the pot value or you cant change in the circuit conditions. but it is linear if the pot is linear.

2,just connect a 530 ohm between variable and fixed point (in use), but this will not be a linear.
Code: 
in 10 k position 10k || 530 = 500
in 5 k  position  5k || 530  = 479
in 3k     450
in 2k     400
in 1k     330
in 500   250 ohms
in 0      0 ohms
You are just doubling the range from the 1st type. But the possibility of inclusion of more than 500ohm value can be avoided, so it can be used in real time circuits

If you are saying rheostat then also you have to consider the current rating required.
 
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