i cant find a logarithmic potentiometer

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

i cant find a logarithmic potentiometer. can i use linear instead?

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Post by DrNomis »

leftfingaz wrote:i cant find a logarithmic potentiometer. can i use linear instead?

You can but you might find that in some cases the adjustment range might be a bit uneven, it will work though..... :thumbsup
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Post by leftfingaz »

DrNomis wrote:
leftfingaz wrote:i cant find a logarithmic potentiometer. can i use linear instead?

You can but you might find that in some cases the adjustment range might be a bit uneven, it will work though..... :thumbsup
is there will be a change in output sound? http://www.geofex.com/Article_Folders/p ... tscret.htm i read this, but i dont understand

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Post by DrNomis »

leftfingaz wrote:
DrNomis wrote:
leftfingaz wrote:i cant find a logarithmic potentiometer. can i use linear instead?

You can but you might find that in some cases the adjustment range might be a bit uneven, it will work though..... :thumbsup
is there will be a change in output sound? http://www.geofex.com/Article_Folders/p ... tscret.htm i read this, but i dont understand

Providing that the value of the pot is the same, there should be no change in the sound, you'll just find that the range of adjustment might be all bunched up at one end, if the pot is being used to control the output level of a stompbox there should be no change in the tone of the sound you get, normally output level pots are logarithmic to give an apparently even response to the human ear, a linear pot should work fine as a gain control for an op-amp stage, again with no effect on the tone of the sound..... :thumbsup


Best way to know is to try it and see..... :thumbsup
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Post by leftfingaz »

thanks.. how about rev log?

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Post by aionios »

Apologies if this is super basic, but I've seen people ask this before who didn't know that 'audio' and 'logarithmic' are the same thing. So they couldn't find log pots, they could only find audio and linear, when audio is what they wanted. I'm just checking to make sure that's not the case here :)

Like others said, you can get the full range with either taper since the value is the same, but for some applications it could be very difficult to use a linear instead of a log. The full range of the control is bunched up on one end, so you have 90% of the rotation that doesn't do much and then 10% that goes so fast you can't fine-tune it. Using linear is OK for breadboarding and testing, but if you're building something to keep (or to give away) then try as hard as you can to get the correct taper.

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Post by leftfingaz »

aionios wrote:Apologies if this is super basic, but I've seen people ask this before who didn't know that 'audio' and 'logarithmic' are the same thing. So they couldn't find log pots, they could only find audio and linear, when audio is what they wanted. I'm just checking to make sure that's not the case here :)

Like others said, you can get the full range with either taper since the value is the same, but for some applications it could be very difficult to use a linear instead of a log. The full range of the control is bunched up on one end, so you have 90% of the rotation that doesn't do much and then 10% that goes so fast you can't fine-tune it. Using linear is OK for breadboarding and testing, but if you're building something to keep (or to give away) then try as hard as you can to get the correct taper.
i know audio and log is the same. also im in philippines. not all component are available here :( so i need to find a subtitute if the component im looking for is not available

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Post by DrNomis »

leftfingaz wrote:
aionios wrote:Apologies if this is super basic, but I've seen people ask this before who didn't know that 'audio' and 'logarithmic' are the same thing. So they couldn't find log pots, they could only find audio and linear, when audio is what they wanted. I'm just checking to make sure that's not the case here :)

Like others said, you can get the full range with either taper since the value is the same, but for some applications it could be very difficult to use a linear instead of a log. The full range of the control is bunched up on one end, so you have 90% of the rotation that doesn't do much and then 10% that goes so fast you can't fine-tune it. Using linear is OK for breadboarding and testing, but if you're building something to keep (or to give away) then try as hard as you can to get the correct taper.
i know audio and log is the same. also im in philippines. not all component are available here :( so i need to find a subtitute if the component im looking for is not available

If you can't find the right type of pot you need you could try ordering it online from one of the many electronic parts suppliers on the internet, Pedal Parts Plus Inc are a good one since they ship overseas.... :thumbsup


Just so you know, if a pot has an "A" next to it's value marking it's a Log (Audio) type, if it has a "B" next to it's value marking it's a Linear type.... :thumbsup
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Post by leftfingaz »

DrNomis wrote:
leftfingaz wrote:
aionios wrote:Apologies if this is super basic, but I've seen people ask this before who didn't know that 'audio' and 'logarithmic' are the same thing. So they couldn't find log pots, they could only find audio and linear, when audio is what they wanted. I'm just checking to make sure that's not the case here :)

Like others said, you can get the full range with either taper since the value is the same, but for some applications it could be very difficult to use a linear instead of a log. The full range of the control is bunched up on one end, so you have 90% of the rotation that doesn't do much and then 10% that goes so fast you can't fine-tune it. Using linear is OK for breadboarding and testing, but if you're building something to keep (or to give away) then try as hard as you can to get the correct taper.
i know audio and log is the same. also im in philippines. not all component are available here :( so i need to find a subtitute if the component im looking for is not available

If you can't find the right type of pot you need you could try ordering it online from one of the many electronic parts suppliers on the internet, Pedal Parts Plus Inc are a good one since they ship overseas.... :thumbsup


Just so you know, if a pot has an "A" next to it's value marking it's a Log (Audio) type, if it has a "B" next to it's value marking it's a Linear type.... :thumbsup
too expensive. life in philippines is very hard almost all filipino dont have credit card just like me. thanks by the way. :D all of my question has been answered

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Post by Lucifer »

The link already provided (http://www.geofex.com/article_folders/p ... tscret.htm) not only explains about pots, but shows you how you can get a linear pot to give a logarithmic type of response by adding a resistor or two.

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Post by Relayer110 »

Here's a circuit that will provide some approximation of a Log curve using a Linear Pot.
I needed to come up with this as I needed to use Linear dual pots whereby one of the pots required a Log curve. The circuit idea is not mine, I found an article in a popular Australian magazine called, Silicon Chip on this conversion.
I hope it helps. :)
Regards,
Relayer :mrgreen: :mrgreen: :mrgreen:

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Post by leftfingaz »

Relayer110 wrote:Here's a circuit that will provide some approximation of a Log curve using a Linear Pot.
I needed to come up with this as I needed to use Linear dual pots whereby one of the pots required a Log curve. The circuit idea is not mine, I found an article in a popular Australian magazine called, Silicon Chip on this conversion.
I hope it helps. :)
Regards,
Relayer :mrgreen: :mrgreen: :mrgreen:

[ Image ]
i will connect a resistor to lung 1 and lung 2? how about rev. log?

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Post by Liquitone »

Rev log is the exact opposite of log. In a logarithmic pot the resistance is more spread out on the first parts of the pots rotation, which is useful for for instance volume controls.
In a lot of LFO designs on for instance phasers, the speed knob requires a more spread out resistance at the other side of the pots rotation, so the changes in speed are spread out more evenly across the pot's rotation. If you use a logarithmic here and wire it backwards it will have the same response, only that when you turn the knob clockwise it will slow down instead of speeding up, which feels counter-intuitive.

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Post by leftfingaz »

Liquitone wrote:Rev log is the exact opposite of log. In a logarithmic pot the resistance is more spread out on the first parts of the pots rotation, which is useful for for instance volume controls.
In a lot of LFO designs on for instance phasers, the speed knob requires a more spread out resistance at the other side of the pots rotation, so the changes in speed are spread out more evenly across the pot's rotation. If you use a logarithmic here and wire it backwards it will have the same response, only that when you turn the knob clockwise it will slow down instead of speeding up, which feels counter-intuitive.
thank for all your answer.. :D

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