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Potentiometer

John Fields
 

Hello,

I'd like to simulate a 500 ohm pot by using a voltage divider: (View
using a fixed-pitch font)

CW
|
[Ra]
|
+---COM
|
[Rb]
|
CCW

and stepping Ra from 499 ohms to 1 ohm in one ohm steps while
simultaneously stepping Rb from one ohm to 499 ohms in one ohm steps.

I tried .STEP PARAM {Rx} 1 499 1 for the ascending resistance, and
that works, but for the descending: .STEP PARAM {Rx} 499 1 -1 doesn't
work.

Matter of fact, it gives me the same result as the ascending!

Help, please?

--
JF
Ganesan
 

I tried
.step param r1 490 10 -10
and
R2 set to {500 - {r1}}

output seems to be all-right...

cheers
AG

On 9/14/2011 12:06 PM, John Fields wrote:

Hello,

I'd like to simulate a 500 ohm pot by using a voltage divider: (View
using a fixed-pitch font)

CW
|
[Ra]
|
+---COM
|
[Rb]
|
CCW

and stepping Ra from 499 ohms to 1 ohm in one ohm steps while
simultaneously stepping Rb from one ohm to 499 ohms in one ohm steps.

I tried .STEP PARAM {Rx} 1 499 1 for the ascending resistance, and
that works, but for the descending: .STEP PARAM {Rx} 499 1 -1 doesn't
work.

Matter of fact, it gives me the same result as the ascending!

Help, please?

--
JF




No virus found in this incoming message.
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It seems obvious to me that the results are the same.
I think that in order to achove what you have in mind Ra should be {Rx}
and Rb should be {500-Rx}
You need only one .step and you do not need braces in the .step

John Fields wrote:


Hello,

I'd like to simulate a 500 ohm pot by using a voltage divider: (View
using a fixed-pitch font)

CW
|
[Ra]
|
+---COM
|
[Rb]
|
CCW

and stepping Ra from 499 ohms to 1 ohm in one ohm steps while
simultaneously stepping Rb from one ohm to 499 ohms in one ohm steps.

I tried .STEP PARAM {Rx} 1 499 1 for the ascending resistance, and
that works, but for the descending: .STEP PARAM {Rx} 499 1 -1 doesn't
work.

Matter of fact, it gives me the same result as the ascending!

Help, please?

--
JF
John Fields
 

On Wed, 14 Sep 2011 12:06:39 -0500, you wrote:

Hello,

I'd like to simulate a 500 ohm pot by using a voltage divider: (View
using a fixed-pitch font)

CW
|
[Ra]
|
+---COM
|
[Rb]
|
CCW

and stepping Ra from 499 ohms to 1 ohm in one ohm steps while
simultaneously stepping Rb from one ohm to 499 ohms in one ohm steps.

I tried .STEP PARAM {Rx} 1 499 1 for the ascending resistance, and
that works, but for the descending: .STEP PARAM {Rx} 499 1 -1 doesn't
work.

Matter of fact, it gives me the same result as the ascending!

Help, please?
---
Ganesan,

E.A.Neonakis:

Thanks, it worked. :-)

--
JF

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