PikantniHumus
New member
Can I substitute the 10k mix knob for a 100k on the Arachnid?
Arachnid Mix knob substitute
- Thread starter PikantniHumus
- Start date
Mcknib
Well-known member
You could but its 10x the value it'll work but not as it should, if it's a B taper you can put resistance across lugs 1 and 3, that'd be your best bet
As a working example let’s say you need a 20K pot but only have a 50K
To find out what resistance you need in parallel between pot lugs 1 and 3 we would use this formula
Rp = 1/ (1/R – 1/Rpot)
Where Rp is the parallel resistance required R is the required value and Rpot the value you have, so following convention brackets first
Rp = 1 / 20 – 1/50 = 0.05 – 0.02 =0.03 we then divide 1 by 0.03 (not 0.03 by 1) = 33.33
So we need a 33K the nearest practical value resistor across pot lugs 1 and 3 or in parallel
The second calculation will allow you to check how close it is to your desired value
R = R1*R2/(R1+R2)
R1 is the pot value and R2 the parallel resistor value from your previous calculation
R = 50 x 33 / 50 + 33 = 1650 / 83 = 19.87 giving you almost exactly 20k
Changing Potentiometer Resistance calculations
All debate regarding how taper is affected aside, here are 2 calculations for you to change what you have to what you need
As a working example let’s say you need a 20K pot but only have a 50K
To find out what resistance you need in parallel between pot lugs 1 and 3 we would use this formula
Rp = 1/ (1/R – 1/Rpot)
Where Rp is the parallel resistance required R is the required value and Rpot the value you have, so following convention brackets first
Rp = 1 / 20 – 1/50 = 0.05 – 0.02 =0.03 we then divide 1 by 0.03 (not 0.03 by 1) = 33.33
So we need a 33K the nearest practical value resistor across pot lugs 1 and 3 or in parallel
The second calculation will allow you to check how close it is to your desired value
R = R1*R2/(R1+R2)
R1 is the pot value and R2 the parallel resistor value from your previous calculation
R = 50 x 33 / 50 + 33 = 1650 / 83 = 19.87 giving you almost exactly 20k
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