All
I have replaced three identical potentiometers with an off the shelf linear potentiometer with matching physical and somewhat different electrical characteristics. This is for a gaming control, and it works well for the game. However there was one thing that concerned me. The cycle life of my replacement is 15,000 cycles .. which is much lower than I wanted. The game specifically does not reveal any data on the original potentiometer, which appears to be an industry standard (they appear not to want you to do this). According to best guess metrics the life span of the potentiometer I used is 25 hours before it degrades. This is based soley on Cycle life, yet the control continues (to my great joy) to function after 100 hours.

I recognize there are many variables here .. the potentiometer is running at exceptionally low current conditions, the cycles encountered is much lower per day than the cycle failure test that was probably run in less than 1 hour. Does anyone have any experience on actual correlation between cycle life testing in the factory and actual life of the potentiometer. I have tried the library, youtube, and other forums ... this appears to be a mostly dead subject, possibly due to the phasing out this element for hall sensors.

So any information videos or practical experience relayed here wold be very helpful. Esp in regards to determining actual potentiometer life correlated to the 15,000 cycles in the data sheet. The game encounters about 1,200 cycles per 2 hours play every 24 hours or more .. (yes I play too much).

 

sensors based on other technologies (optical/inductive/hall...) may have far greater longevity

 

The cycle test is probably performed where 0% to 100% wiper rotation and back is one cycle so there's maximum wear on the wiper per cycle.
Your "cycle" is likely less than that, so the wear is correspondingly less per cycle.

But as pm noted, if you want longer life, then you will need to consider some non-mechanical form of a potentiometer, such as a digital pot controlled by an optical quad encoder.

 

With respect please remember this is a pre existing game in which I am trying to source potentiometers. I was worried that the whole alternative sensor discussion, would ensue. While I am aware this is a far superior solution, it is not currently one that is practical to pursue. Yes a full cycle is starting position (usu full cclockwise to full clockwise back to the starting clockwise position). Now if anyone out there knows anything about cycle tests in correlation to real potentiometer life esp with gaming weigh in. Again yes non contact sensors are far far better .. and I appreciate the discussion.

 

I understand a pot with a cermet track would last longer than one with a carbon track.

 

All
I have replaced three identical potentiometers with an off the shelf linear potentiometer with matching physical and somewhat different electrical characteristics. This is for a gaming control, and it works well for the game. However there was one thing that concerned me. The cycle life of my replacement is 15,000 cycles .. which is much lower than I wanted. The game specifically does not reveal any data on the original potentiometer, which appears to be an industry standard (they appear not to want you to do this). According to best guess metrics the life span of the potentiometer I used is 25 hours before it degrades. This is based soley on Cycle life, yet the control continues (to my great joy) to function after 100 hours.

I recognize there are many variables here .. the potentiometer is running at exceptionally low current conditions, the cycles encountered is much lower per day than the cycle failure test that was probably run in less than 1 hour. Does anyone have any experience on actual correlation between cycle life testing in the factory and actual life of the potentiometer. I have tried the library, youtube, and other forums ... this appears to be a mostly dead subject, possibly due to the phasing out this element for hall sensors.

So any information videos or practical experience relayed here wold be very helpful. Esp in regards to determining actual potentiometer life correlated to the 15,000 cycles in the data sheet. The game encounters about 1,200 cycles per 2 hours play every 24 hours or more .. (yes I play too much).

Hi,

Why didn't you at least go for potentiometers with life 100k cycles rather than 15k.
One cycle would be the rotation from one angle to another angle and back again. Even if the movement is only 2 degrees that section will wear out and cause a change in resistance over time and use. The half-life change in resistance might be small though.
Bourns makes some decent pots with 100k cycle life.

 

Ok appreciate the feedback and have actually located a potentiometer with 100k cycles which is by the way hard to do after validating physical and electrical compatibility via data sheets (if they even exist) you dumpster dive into. Most pots listed have a Durability Operating life of 10,000 cycles. This process has taken me hours because no one lists the pertinent data on the summary page (sometimes the www sucks).

HOWEVER the question really remains unanswered. Now if anyone out there knows anything about cycle tests in correlation to real potentiometer life esp with gaming weigh in. Please keep in mind this gold standard of cycle life does not appear to have any real explanation that I can locate via the www. I would love to find a writeup, or video explaining all the minutia of this supposed valuable test. Esp in regards to the entire philosophy behind it and its practical applications. Please no supposition .. I can make up my own stories like this is an exhaustive point of failure test, giving absolute min cycles of reliability. What I am missing is what electrical loads are used if any, how long the test is generally run for why its a standard etc.

I am hoping someone can give me some more information on this. As I must throw up my hands in ignorance I am not going to point my finger back. I appreciate al responses.

 

Ok appreciate the feedback and have actually located a potentiometer with 100k cycles which is by the way hard to do after validating physical and electrical compatibility via data sheets (if they even exist) you dumpster dive into. Most pots listed have a Durability Operating life of 10,000 cycles. This process has taken me hours because no one lists the pertinent data on the summary page (sometimes the www sucks).

HOWEVER the question really remains unanswered. Now if anyone out there knows anything about cycle tests in correlation to real potentiometer life esp with gaming weigh in. Please keep in mind this gold standard of cycle life does not appear to have any real explanation that I can locate via the www. I would love to find a writeup, or video explaining all the minutia of this supposed valuable test. Esp in regards to the entire philosophy behind it and its practical applications. Please no supposition .. I can make up my own stories like this is an exhaustive point of failure test, giving absolute min cycles of reliability. What I am missing is what electrical loads are used if any, how long the test is generally run for why its a standard etc.

I am hoping someone can give me some more information on this. As I must throw up my hands in ignorance I am not going to point my finger back. I appreciate al responses.

Hello again,

Ha ha, I like your satire about this issue, and I can see you definitely have heart. That's very admirable. Some would get back here and start yelling and screaming because they got roundabout answers to a specific question forgetting it's a free service and different people have different ways of handling things. So you are the welcome exception.

Now for the best specific answer I can think of at the moment, sometimes it becomes necessary to contact the manufacturer. That's the only way sometimes. That's actually the best way to handle this because they could all have their own definition of what the test is and why it is used.
Back when I worked in the industry, I was on the phone quite a bit but even more so waiting for callbacks with information about different technical issues. Back then the internet was just being thought about so not everyone had an email address, if anyone, so the land line telephone was the only real way to get information that was not already written down. It's a lot of work, but design work is not the easiest thing in the world. Modification is also a part of that process, so sometimes you have to be ready to sit down and roll up your sleeves and dig down into the brass tacks. It takes time and effort, and perseverance. If you do not give up you should be able to get some useable results. After years of doing this, I can say that it works.
Some of the companies I remember that were the most helpful were Analog Devices and some of the parts outlets. Some took several days to get back to me, maybe even weeks, like the power company that serviced that area.
This might actually be better than getting an answer on the web on a message board like this anyway. You may run into someone who already did this though and that makes it easier. Unfortunately, I do not remember all the things we did way back then and we did use potentiometers on a lot of stuff, and they had to be good because they controlled devices that handled thousands of watts.
I do remember one though ... that was a Bourns 10 turn wire wound pot. That was preferred at the time. We even purchased those little metal indicators that are used with them that count the turns mechanically and display it so you know where the pot is set.

I just remembered another issue I ran into some years back.
This was with a stereo I purchased from Radio Shack. It had the best sound I was very surprised.
The issue that came up was with the volume controls for left and right channels.
They both worked great for a while, but then after some time the right channel started scratching when I changed the volume for that channel. The left channel worked fine just like when new, but the right channel pot obviously had a problem. I tried spraying it and it would work for a few days then start making that static sound again when the volume was changed.
It seems that one pot worked longer than the other in this application. That indicates that there is some randomness in the cycle life involved also.
This also showed up in two bench power supplies I had worked on. Three of the pots were bad, one of the pots was still good. I think the second unit had two bad and two good (long time back now).

Oh, BTW, some pots are tested in a vacuum, and some allow a rotation of the full 360 degrees with a small deadband. Those would be tested for the full rotation, and the cycle life would be called rotational life, so 100000 would indicate 100000 complete rotations (not back and forth). They could also have a rotational speed limit also.

Some pots you can open and clean. More important though might be that you can take a pot apart and check it for wear and dirt and stuff. That could tell you why they are failing. It could be part track wear, part wiper wear, and part decreased wiper spring force, as well as contamination from gasses and dirt.

I think the suggestions for upgrading the type of pot completely came from trying to solve this issue once and for all by using a different technology. That could be very difficult to implement sometimes though, and sometimes impossible.

 

Thank you MrAI I found this response significantly productive. Both in content and suggestions. As for the rest of the participants, thank you for your valuable time and expertise. In about 5 years or so (when our cars start really driving themselves) I do think this will be a very dead subject. In the meantime I cringe at the thought of probably hundreds or even more type written and or mimeographed papers in files mouldering away in file cabinets, detailing this very subject. They never quite made it to the internet.

So yes I will put out some feelers to potentiometer suppliers ad see what they say about this.
My next plan is to run the 15k cycle pots to the grave .. do a forensic autopsy, and multiply the service life I get in hours by 6.67 for its 100,000 cycle replacement. Im not sure how reliable this will be but .. time will tell! In the meantime I will let everyone in on what I find out here .. if I ever do. I really enjoy tinkering and this is a great deal of fun for me.

 

Thank you MrAI I found this response significantly productive. Both in content and suggestions. As for the rest of the participants, thank you for your valuable time and expertise. In about 5 years or so (when our cars start really driving themselves) I do think this will be a very dead subject. In the meantime I cringe at the thought of probably hundreds or even more type written and or mimeographed papers in files mouldering away in file cabinets, detailing this very subject. They never quite made it to the internet.

So yes I will put out some feelers to potentiometer suppliers ad see what they say about this.
My next plan is to run the 15k cycle pots to the grave .. do a forensic autopsy, and multiply the service life I get in hours by 6.67 for its 100,000 cycle replacement. Im not sure how reliable this will be but .. time will tell! In the meantime I will let everyone in on what I find out here .. if I ever do. I really enjoy tinkering and this is a great deal of fun for me.

Hello again,

Oh yeah you just touched on another aspect of this, and that is doing some testing yourself to see what happens. It's hard to beat that. As time goes on you will get a better idea what you are dealing with just from your own investigation.
Once you take one apart you can check for track wear and wiper wear. It might be hard to test the spring tension though but maybe you can get a feel for that too. I would bet it is ok though.
The ones I took apart a long while back I remember on some the track was worn. That of course screws up the resistance over the range of rotation. There is no way to fix that I don't think.

I remember one thing I tested where I could not find too much information on, and that was testing a certain type of hot glue for its insulation properties. I found it to be very good, surprisingly good, and some others on the web tested it too. It would make a good insulator, but then what happened was I found out that it cracks if there is any movement that stresses the bulk of the hardened glue. Once it cracks, moisture could set in, and that means there goes the insulation properties ... from really good to really bad.
Live and learn.

Oh, I almost forgot. There is another type of potentiometer made for high precision applications. It has a spiral element in it and when you turn the knob the wiper follows the spiral and that spiral acts as the 'track'. They are highly reliable.
What I do not know though is if they make them in a small enough size to fit into your device. I'd also have to look up what they are called if they have name. The one I had was 1k and it was multi turn but it was big, at least 3 inches high and 2 inches diameter. (ha).
So that may not work anyway unless they make small ones that have single turn motion.
Actually maybe that is how the Bourns 10 turn pots are made.

 

Here is a suggestion based on the requirements of the application, which is that the manufacturers of broadcast and studio equipment are quite demanding on product life, and so discovering what brands and models they choose could be useful. Industrial stuff needs more to withstand abuse, so that area is rather different.

 

Here is a suggestion based on the requirements of the application, which is that the manufacturers of broadcast and studio equipment are quite demanding on product life, and so discovering what brands and models they choose could be useful. Industrial stuff needs more to withstand abuse, so that area is rather different.

Hi,

I would think it depends more on what the application is. Do the application functions need to be adjusted frequently or not.
Stereos and mixers would probably have to be adjusted a lot, but then so do bench power supplies.

I was recently looking for a product that has sort of a similar function: a motorized variac. Kind of expensive.

 

Motorized "Variacs" or "Powerstats" have been available for many years, today it is much less likely than 50 years ago. Often they used a Superior Electric brand 72 RPM synchronous motor and a single stage gear reduction drive. I am not sure where you would find a new one today.

 

One thing several have missed is that the application is in an existing video game console. So it needs to replace a fairly small and cheap variable pot.

 

Motorized "Variacs" or "Powerstats" have been available for many years, today it is much less likely than 50 years ago. Often they used a Superior Electric brand 72 RPM synchronous motor and a single stage gear reduction drive. I am not sure where you would find a new one today.

Yes I agree, although I did find some they are so expensive not worth even mentioning. A new 20 amp variac can be had today for less than $100 USD, but a motorized one could be $1000 or more. I could probably motorize one myself for MUCH less than that.

I was thinking of doing a slow AC regulator circuit that regulates power not voltage.
I don't want to get too far off topic here though so maybe I'll start a new thread.

 

An "AC Regulator" using a motor driven variable transformer design has been published in an older book I was shown 60 years ago. The serious concern is that the moving contact on the motor driven device is carrying the whole load current. That is why the utility companies use tap changers instead. Vastly extended product life.

 

One thing several have missed is that the application is in an existing video game console. So it needs to replace a fairly small and cheap variable pot.

i don't think anyone missed that... if anything is missing it is the dose of reality.

small and cheap pot for something obscure, small volume and inconsequential is not going to be on a high priority list of any designer/manufacturer. nobody is going to start meticulous endurance testing for something that is on a shoe string budget. industry works for $$$. you want something, you need to spend money or do it yourself. beggars can't be choosers.

you want something robust, you can have it... several technologies exists. and while it does not cost and arm and leg, it is not going to be pennies. you just need to spend a weekend tinkering...

if you want something cheap, and low effort, get several potentiometers and replace them when they fail. this may help you get over the game addiction.

potentiometers are among cheapest products you can get though quality products are not cheap at all.

several types exist. the crappiest are carbon film type. not only they are temperature dependant, and have poor tolerances, but they wear out rather easily since the resistive element is very thin. cermet is more durable and - more stable. plastic resistive element may be the candidate to consider since the element is thicker so wear can be considerable (lots of use) before it actually fails. mechanical wear of the wiper is one of concerns. but... current is another. any long life product will have stated in the datasheet that current need to be kept very low. something in the microamps. so for longest life, opamp buffer circuit is needed.

 

I have speculated as to the possibility of creating some version using an LDR and a variable shutter with an LED light source. I did see that they were linear, I had guessed that meant resistance versus rotation but now I winder if it is linear motion. There are some interesting sensors used now for inputs to surgical robotics, which might be good for millions of cycles. Also force sensors for control sticks that don't move. So it might even be a business opportunity for somebody to create a replacement part that could last "forever". It might sell a lot, if offered as a replacement service. I see that gamers can be a new market.

 

An "AC Regulator" using a motor driven variable transformer design has been published in an older book I was shown 60 years ago. The serious concern is that the moving contact on the motor driven device is carrying the whole load current. That is why the utility companies use tap changers instead. Vastly extended product life.

Hi,

Yeah that would be a concern. The current would be relatively low, but still the back-and-forth motion might wear it out too soon. Might have to buy a stack of replacement contact brushes

 

Hi,

Yeah that would be a concern. The current would be relatively low, but still the back-and-forth motion might wear it out too soon. Might have to buy a stack of replacement contact brushes

Not only brush wear but worse, localized heating because of higher resistance. And so it can lead to insulation burning at higher loads. So there must be adequate overload protection included. So while AC voltage regulation can work very well, it does have limitations that lead to it not being commonly used.