Mono Vs Stereo Sliding-Potentiometer - Page 1
Forum section: electronics / beginners

author: Charkel
author_rank: Contributor
timestamp: March 30, 2018, 05:16:58 pm
content: Hi!I am buying a linear/sliding pot for my next project. I have noticed there are both mono and stereo versions.These one I am interested in:Mono:https://www.conrad.com/ce/en/product/675420Stereo:https://www.conrad.com/ce/en/product/675438My question is simple, what is the difference between stereo and mono when it comes to potentiometers?Thankful for any help!

author: picandmix
author_rank: Frequent Contributor
timestamp: March 30, 2018, 05:44:28 pm
content: Hi,The only difference is that the stereo version has two carbon tracks vs the monos single track.For general use they are fine.Be aware that pots , like anything else, come in different qualities, so if you are using this for a high quality low noise pre amp etc you would be better looking at better devices which offer lower noise and great accuracy between tracks.View the datasheet for those pots and look at the Noise, Tolerance and Gang error, then compare them with the Alps ones.

author: ebastler
author_rank: Super Contributor
timestamp: March 30, 2018, 05:49:11 pm
content: In other words, a stereo slider potentiometer is just the same as two mono potentiometers mounted side by side, with a common handle to move both sliders in sync.

author: Charkel
author_rank: Contributor
timestamp: March 30, 2018, 05:57:16 pm
content: Quote from: picandmix on March 30, 2018, 05:44:28 pmQuote from: ebastler on March 30, 2018, 05:49:11 pmSo if I understand correct: The stereo will give double values at output but they will still be the same? Maybe they have double connections for output even?Datasheets on conrad are IDENTICALJust FYI This is will be used for a HID device for gaming connected to a handbrake.Prices seems less on the stereo version. Can I use that one for my project?

author: ebastler
author_rank: Super Contributor
timestamp: March 30, 2018, 06:09:56 pm
content: Quote from: Charkel on March 30, 2018, 05:57:16 pmWell, if you have only one signal to process ("how far has the handbrake lever been pulled?"), there is no point in using a stereo pot. Stereo pots are meant if you have two deparate signals, but want to attenuate them by the same amount.(Think of the left and right channel of a stereo audio signal, where you want to control the volume for both channels at the same time. The two signals remain separate inside the pot at all times. But the sliders, which select the resistive divider ratio, are always moved to the same position in the left-channel and right-channel potentiometer.)If you already have a stereo pot, and only want to process one signal, you can simply use just one half of the stereo pot and leve the other pins unconnected.

author: picandmix
author_rank: Frequent Contributor
timestamp: March 30, 2018, 06:11:11 pm
content: Hi,No, they are two totally separate devices.See page 3 of the datasheet, each track has its own set of 3 pins.Sure it will be fine for your use.

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 30, 2018, 06:18:47 pm
content: Quote from: Charkel on March 30, 2018, 05:57:16 pmWow, I am not sure what that even means. A dual (or "stereo") potentiometer is simply TWO INDEPENDENT potentiometers crammed into a common case and with a common control (a shaft for a rotary pot, or a sliding tab for a slide-pot).QuoteBecause a dual/"stereo" pot is simply two IDENTICAL single/"mono" pots in the same case.QuotePrices are probably less because they sell more dual/stereo pots for people making audio projects.You can use any dual/stereo pot for your project by simply connecting to ONE of the sections and ignoring the other section as if it doesn't exist.It is misleading that Conrad calls a single-section pot "mono" and a dual-section pot "stereo:"Since these are LINEAR taper, they are not really audio controls anyway, so "mono" and "stereo" don't really apply.A LINEAR pot is exactly what you need for your project.If the dual ("stereo") pot is cheaper, then buy it. You would connect to only one side. Keep the other side as a "spare" if something goes wrong with the first side.

author: Charkel
author_rank: Contributor
timestamp: March 30, 2018, 06:24:25 pm
content: WOw thank you everyone for the answers! I think I got it now, i see there are both Linear and another kind!I HAVE ANOTHER QUESTION.I see that some are 0.1W and most 0.2W but some even 0.5W. Why would that matter?

author: Bassman59
author_rank: Super Contributor
timestamp: March 30, 2018, 06:45:37 pm
content: Quote from: Charkel on March 30, 2018, 06:24:25 pmThe "other kind" is logarithmic taper. And there's no one log-taper pot!QuoteIt matters if you expect to dissipate a lot of power in the pot. Consider the voltage across it (top and bottom, not the wiper) and its total resistance. If you put 10 V across a 10k-ohm pot, that's 10 mW.

author: ebastler
author_rank: Super Contributor
timestamp: March 30, 2018, 06:57:56 pm
content: Quote from: Charkel on March 30, 2018, 06:24:25 pmJust to be sure: You want the linear type!Quote from: Bassman59 on March 30, 2018, 06:45:37 pmSorry, I don't get that statement.

author: Bassman59
author_rank: Super Contributor
timestamp: March 30, 2018, 07:03:01 pm
content: Quote from: ebastler on March 30, 2018, 06:57:56 pmLookherefor Alpha's list of potentiometer tapers. There are quite a few! Basically, it comes down to how the designer wants the circuit to respond to knob-turning.

author: ebastler
author_rank: Super Contributor
timestamp: March 30, 2018, 07:10:07 pm
content: Quote from: Bassman59 on March 30, 2018, 07:03:01 pmAh, thanks. I am aware of the wide variety of logarithmic pots. It was just a language issue; I did not get the "no one" idiom. Thank you for clarifying!

author: Bassman59
author_rank: Super Contributor
timestamp: March 30, 2018, 07:11:15 pm
content: Quote from: ebastler on March 30, 2018, 07:10:07 pmOh, wow, I had not even considered the language difference. Perhaps better would have been for me to say, "No single ..."

author: paulca
author_rank: Super Contributor
timestamp: April 05, 2018, 09:02:32 am
content: Quote from: Richard Crowley on March 30, 2018, 06:18:47 pmI ran into this recently and you might be surprised that audio designers try and avoid log pots quite readily.The reason given in Small Signal Audio Design was that... well, log pots suck. Their taper tolerance and inter-pot balance is often considerably poorer than their linear counterparts. (Of course that book is quite old).They go to some great lengths to get log law from a linear pot.On the OPs problem. In a real car such a sensor would have multiple potentimeters. Usually 3. A micro-controller compares the three values and discards any value significantly different, then averages the other ones. When it gets three values out of tolerance it puts a warning light on and raises a fault code.In your case you could take both tracks and average them.Also, a log pot would not be such a bad thing. A real handbrake is arguably log. For a lot of it's travel it does virtually nothing, then as it starts to catch it rapidly increases with little movement of the handle until finally it locks. This would usually be done in software and the mechanics done with rubber bungs to simulate the handbrake pulling against something (the shoes).Of course to go "HiFi" you don't want a pot at all, or at least you want to compliment it with a load cell at the end. Similar to high end simulator brake pedals. The pot tells you the travel, but the load cell tells you how hard they pull the handle once it gets to the engagement point. Less important on a handbrake as they are "self energising", so they don't need a lot of pressure, unlike disc brakes which are inefficient and require increasing pressure to produce more braking.