making your own reverse log taper pots

Frequently asked question regarding resistors, potentiometers, types, requirements, ratings etc.
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chris_d
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Post by chris_d »

Deaj wrote:
Barcode wrote: i wonder if the taper of the drive pot might need to be linear instead...
I found that a reverse audio taper works very well.
Or if you are really cheap, and don't mind messing with yourself a little, just wire the audio taper pot backwards. I do that on most of the things i build that call for RA pots. After a while of using the pedal that way i don't even think about the fact that it is backwards.

-chris

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modman
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Post by modman »

chris_d wrote:
Deaj wrote:
Barcode wrote: i wonder if the taper of the drive pot might need to be linear instead...
I found that a reverse audio taper works very well.
Or if you are really cheap, and don't mind messing with yourself a little, just wire the audio taper pot backwards. I do that on most of the things i build that call for RA pots. After a while of using the pedal that way i don't even think about the fact that it is backwards.

-chris
Wiring a pot backwards isn't the same as a reverse logarythmic pot, but you can make a antilog (C) 50k pot by wiring a 100k resistor across the outer lugs of a 100k linear (B). The result is dependent on the exactness of the linear taper,but it might be better than an average antilog pot (and cheaper).
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chris_d
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Post by chris_d »

modman wrote:Wiring a pot backwards isn't the same as a reverse logarythmic pot, but you can make a antilog (C) 50k pot by wiring a 100k resistor across the outer lugs of a 100k linear (B). The result is dependent on the exactness of the linear taper,but it might be better than an average antilog pot (and cheaper).
It is odd, but i've done it both ways, and i usually prefer the backwards standard audio pot to the linear pot with the resistor. Maybe my hearing isn't properly logarithmic! :D

-chris

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Post by modman »

http://www.geofex.com/Article_Folders/p ... tscret.htm

If you look under Tapering, you'll see that an average log pot is much more like (3), so altering the taper of a linear pot with a resistor will always result in a more "log" taper than the ones you buy as log.
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MorticeTenon
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Post by MorticeTenon »

I stumbled on a way to get reverse taper pots during some investigative bungling.....
The top wafer of a Audio taper 16mm Alpha pot is a reverse taper if it is turned upside down and put on the bottom. Note the 24 mm pots don't do it.
BTW, these pots are pretty easy to dissassemble and reassemble by bending the lugs. And since the axle is out the "D" can be swapped to a spline or vice versa.
Hey...I'm new to all this: let me know nicely if I'm wrong here, or if it's common knowledge.

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Post by unbeliever »

http://www.geofex.com/article_folders/p ... tscret.htm

I remember reading about the disassembly / flipping thing somewhere else many moons ago also ... but it's a cool idea, and very handy for 'one-offs'...

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Post by Silent Fly »

I found this (clic "Tapered Pot" on the left) interesting. I never actually tested it though.

With a Taper = 90% it should be reverse taper...
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Post by g0d5_g1ft »

modman wrote:
chris_d wrote:
Deaj wrote:
Barcode wrote: i wonder if the taper of the drive pot might need to be linear instead...
I found that a reverse audio taper works very well.
Or if you are really cheap, and don't mind messing with yourself a little, just wire the audio taper pot backwards. I do that on most of the things i build that call for RA pots. After a while of using the pedal that way i don't even think about the fact that it is backwards.

-chris
Wiring a pot backwards isn't the same as a reverse logarythmic pot, but you can make a antilog (C) 50k pot by wiring a 100k resistor across the outer lugs of a 100k linear (B). The result is dependent on the exactness of the linear taper,but it might be better than an average antilog pot (and cheaper).
a 100k resistor wire across pin 1 and pin 3 of a 100K linear resistor would make a 50k reverse log pot? is this correct? Im new to this and Im in need of a 10k reverse log pot. would the sweep be the same? I mean I wont have to turn the knob backwards like in the case of wiring an audio log CCW?

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