Excellent. Just the 2nd if your vids I've seen (1st was 15 min ago) and I'm loving it! I sub'd, hit the bell, selected all... looking forward to the rest!
Alan, I've really missed your regular output in recent months but appreciate times and circumstances change and you focus on others interests. I always particularly enjoyed your 'back to basics' videos so it was really nice to enjoy one of these hugely informative sessions once again. We don't know each other but your videos have helped me so much over the years so a big thank you for all of them.
I appreciate your comments. The slowing down of video content creation on my end is not a reflection of any lack of interest, but just a lack of time. A lot of folks don't realize that each minute of published video content represents 10, 20, 30 minutes or more of total work on my end. So, a 10 minute video represents hours of work in many cases. I hope that I don't lose any loyal viewers like you simply because my "day job" is demanding more of my time.
@@w2aewYou'll never lose your loyal viewers as the reason is in the description...'loyal'. Very best regards and thanks for taking the time to explain.
Thanks, Allen! Something I "kinda knew," but never payed enough attention to. It explains why I was having so much trouble with my breadboard experiments the other night, and contact cleaner didn't seem to help the little trimmer!
Just use one across a 1v DC supply, feeding the output into an AC coupled amplifier. Turn back and forth around 100 times end to end and they will get scratchy, especially if you leave them in one position for a few months as well.
Guilty, as a hobbyist I've never heard of this and honestly can't say I've ever thought to opened a datasheet for a potentiometer until now... I guess it's one of those parts that's easy to take for granted because they're so inexpensive and are simple in terms of theory/operation. Thanks for the great video!
thanks for sharing this, i am indeed a young player my self and im glad i watched this because i was going to use the the trim pot for the same use case as a rotary pot, i shall get some rotary pots and use them instead. I was going to use the trim ones because i had them laying around, but ill just get the rotary ones, thanks again for sharing.
I tend to use the trimmers in my initial circuit design but once I get a circuit I'm basically happy with I change to using a control pot, that way I get the right feel of the circuit before I build it up for proper.
excellent video! i never thought about that.... well, i usually only use use normal pots and i use trimmer pots where there is no place so, inside but really interesting and good to add to my knowledge! thanks again!!!!
i wish there was a type of system where we got a handful of chassis and a handful of pcb's with that resistor trace. that way when we burn out a pot, we can just swap the inside. also, then we could have better quality chassis. sure would fit in the bins better too. i have a couple thousand pots and they take up sooo much space !! could also swap values without unsoldering !!
Thanks I was about to try to use one of those sparkfun trimmers for a crucial feedback placement that would have thousands of rotation cycles. I’ll be looking for something else now. Thank you.
Alan, great video. More videos like this one, please. Educating on things that are usually not even considered. Also, teaching on what to look on the datasheets. 73s
..and if used as a divider off of a voltage you can over-current and burn out a smaller pot.. not that they should have a lotta wattage, but I've seen pots burned on one side of the sweep. Also log vs. linear is worthy of note.
Reminds me of the very low quality experimenter kits from a once thriving electronics chain store , when I was in grade school 50 years ago. No rating at all. It discouraged many beginners. Thanks to a local electronics store that is still in business, sold quality commercial grade products. I still make a living in electronics. From circuit board repair to installing campus wide, fiber optic connected AV systems.
Good video, and I always knew that these trimmers aren't used for control but I'd never thought that they withstand just 400 turns, thanks for the great advice
Another gotcha is pin arrangement. The same trimmer can have various pin arrangements indicated by a letter or number in the part number. The delta arranged pins can have a couple different spacings and won't fit the board if you order the wrong one.
As always very comprehensive..keep posting good stuff..could you kindly post topics on: 1.basic antennas, its characteristics, its measurements and best practices 2.differrent coax types and its applications 3. Stub matching 4. Antenna arrays Thanks and best regards
This goes for switches too. If you check the data you can find some are rated for far more transitions than others. It's important to consider longevity when selecting parts. Also, as someone else mentioned, it's easy to overload the small trimmer. It takes only a few volts across the trimmer to get too much current flowing and exceed the wattage rating.
Funny, I think that I heard that anecdotally somewhere on TH-cam or during the ham radio classes that I took. Also watching when watching old ham radio repair videos all of those pots (resistors, capacitors and inductors) were so very touchy that I never imagined that they would have any real life expectancy other that a few settings.
Nice video. Would really like if you could also cover 4 terminal potentiometers (center tap). Also their application on volume and loudness controls. Thanks!
That's right they are a rarity this days nobody really uses them this days. So you might as well just use a normal logarithmic pot in audio with a little modification of the components around it Should work as a good as any.
Excellent review. Also it wasn't mentioned, but multi-turn pots and trimmers nearly always have a linear profile when plotting a change of resistance against a given amount of physical adjustment, whereas the single turn pots usually have an inverse-logrithmic profile for changes in resistance with respect to a given amount of physical adjustment. This is often referred to as a logrithmic tapre.
Speaking of trim pots. I recently found a good deal from an Ebay seller that had two new vertical attenuation modules for my old Tek 485. My channel 2 had a bad pot on the variable adjustment on the center of the volts per division rotary switch. The coupling switch also had something broken on it and didn’t lock in half the time. Long story short, I purchased it and it works like it should, only issue is when switching between voltage per division the trace jumps around on the 1 Meg input setting where it stays pretty static on channel one. The new module doesn’t jump around nearly as much as the old one, maybe within one graticule where the old module would jump half the screen. I deduct that there is some kind of balance adjustment because of the invert function on channel two? Just curious if you could give me a pointer on what trim pot to adjust? Found something in the manual that kind of gave an indication but not very in depth. I don’t have a service manual. Other than that the old girl works pretty good for a 40 year old scope I got for $50. The module was $55 lol. But it was worth it to have it working pretty much normal. I love it for testing and checking circuits in old tube amps. I like my cheap Rigol 1054z for all the measurements it has, but those old Tek scopes are like pieces of art inside. Thanks for all you do Alan.
W2aew, can you explain more about the potentiometers "tapers" there is different taper curves like log, antilog, linear, etc. I'm not sure what to use as to graph chart a potentiometers taper maybe a curve tracer might work to test a pots taper type
There is also the difference between an audio taper and a linear taper, which took me a long time to realize. Alan, thank you for all of your video efforts and for sharing your knowledge. I learned so much from you and am very grateful. Greetings from Arizona.
Please continue your back to basics videos.. at 67 I am teaching myself how to do electronics and your way of teaching is very good.. I can understand what your saying very well and am learning new things.. It is exciting! So carry on I have subed up and want to learn more.. I have visited your site and watched all the "back to basics".. I have always been interested in ham radio also.. But do not remember any of my morse code from the boy scouts.. Do they still require you to know it to get a license? that maybe my next project.. But down the road some... Thanks again.. I really appreciate you taking the time to do this..
Thanks for this video. I bought a kit of guitar pots (On amazon of course... and regret it already) and it came with both kinds. I cannot figure out why they sent trimmers for a guitar building kit, as the pots need to be adjusted regularly, it makes no sense.
Love your videos!!! Can you make one teaching the propper way to clean and lube faders?There are a bunch of videos but all of them or use non recomended cleanners for eletronics and usually they use some sort of grease or oil!! In case of the faders wouldnt be better to use some sort of graphite or carbon to improove conductibility?Also what can we do to "Tune" them! Thank you for your videos,keep up the good work ;)
Great tip. I will definitely keep this in mind for the future. How about the max current rating? Is it usually higher for control pots than for trim pots, or is it most often about the same?
Yes, max current, particularly through the wiper, is generally higher for controls than trimmers. However, in both cases, it's best to try to design circuits that minimize wiper current if possible.
Great video. I never even considered this. Ive gotta say though, I have some pots similar to the control pot you showed on Sparkfun and they're actually not that great for breadboards cuz they have those 2 metal tabs that stick out at the bottom. Even if you bend them up and out of the way, the pot never sits flush with the board. It's always at an angle. I usually just throw some female to male dupont connectors on them or just solder some wires on.
Always make sure to use SHIELDED CABLE and not wires on pots that are not mounted directly to the circuit board! Wires won’t work at RF and even as low as audio frequency on certain projects I’ve done using wires on pots will cause the circuit to go nuts.
I actually always wondered why a capacitive variation is rarely being used, since you can basically have two floating sides, which means less wear over time. Especially with all these microcontrollers nowadays, but even with analog it's not to difficult to converter capacity to pwm to a voltage or something
Right on my friend. Your input is very much appreciated. There's a lot to be said for digital trim pots and software support for multiple setting situations. I have several microcontroller designs that have many trim pots that could benefit from this knowledge. The break-even point has to be pretty low for your advice to be effective. New sub. Great information. Happy to get good input.
Nice simple video! I have a request for a video on the input and output impedance of rf transistor circuits. I have found some brief and very general descriptions but very few sources go into what the actual impedance is and even fewer that do a good job of explaining why it is that impedance. Definitely not a back to basics video but I think it could help people understand rf designs much better if they knew why the matching networks are there on the input and the outputs. Maybe this would be a couple of videos? Thanks!
Hmm, good point Alan. I always hated those "gear" style trimmers since the screwdriver adjustment slot was always oriented vertically and invariably there was another component in the way forcing you to turn it manually...grrr; the trimpot with the knob would have been so much easier! Keep the basics videos coming, I always forward the link to our club's email reflector. 73 - Dino KL0S
They both cause a delay, so from that standpoint they're pretty similar. However, a phase shifter is typically used for RF applications, often at a specific frequency, while a delay line could be more broadbanded.
w2aew, thanks for replying, the first control pot you featured is the type of control I'm looking to use in my project. Is it possible to change a trimmer pot to a control pot by simply unsoldering the trimmer from its board. (In my case a buck boost converter). And soldering three wires to the controller? Your input would be helpful.
I'm having a tough time getting an answer to this question. Can you tell me if there is a pot that can be turned left or right with the center being off? What I'm trying to achieve is,I have a pwm motor speed controller for my trolling motor. The way I have it set up is,I removed the trolling motor speed control drum switch that attaches to the end of the handle and replaced it with the b100k potentiometer that came with the controller. This works fine but to go in reverse,I have to use the rocker switch. An on off on rocker switch to be specific and have to turn the handle clockwise for both directions. It would be great if there is a pot that can be turned either way with the center being off. Preferably with a center detent. This way I could make it work in conjunction with the rocker switch. I'm thinking that I can make a sort of cam that would activate the rocker either way when the pot is turned with center being off. I would just like to be able to use it without having to use the rocker switch for both directions,just with the handle. Any info will be appreciated. Thanks.
@@w2aew The potentiometer that came with my pwm speed controller has an off position. When it's turned a the way to the left,it clicks off and shuts down the controller.
Minn kota has a couple variable speed trolling motors that use a 3 pin pot. Turn right for forward and left for reverse. The center is off. I own one of these but prefer the one I'm working on as it performs better than the minn kota. I actually took the pot off the minn kota and connected it to the other pwm but it did nothing. It must be set up to work with the minn kota control board only.
In most cases where the connections are in a row - the pot value is read by reading the resistance across the outer two connections. If there is any doubt - measure the resistance across all three combinations - the largest value read will be the pot's value.
Thanks for making this video. I actually have a question related to this topic. First, let me explain my project. I'm going to try to build a fuel meter system and I want to make the circuit as simple as possible even though I have to admit that I still consider myself a beginner. To measure the fuel level I am going to use a pressure sensor. By the way, this is for a motorcycle. The sensor that I have gives voltage as an output (5 - 4v). And then I am planning on using an Arduino to process that data and send it to a fuel gauge. Here begins the challenge. The fuel gauge that I have takes in as input, resistance: 90 ohms or above = empty and 10 ohms = full. The problem is that I was planning on using a digital potentiometer controlled by the Arduino to vary the resistance but unfortunately (at least from what I know) I could no find a digital pot that can output such a low resistance. Many of them are well over 5k. Maybe you know of some ICs that can do the job? So I am left with two options: 1- Develop a mechanical solution which would be based on a stepper motor rotating a trimpot to obtain the desired resistance. I know this will give a very smooth output. But I really want to avoid taking this path because it would take up more space and I want to make my circuit without any moving parts. Let alone the added complexity. 2 - Use a group of staggered resistors to control the output. Maybe by increasing steps of 10 ohm resistors. It would be something like 10 - 20 - 30... until I get to 90 ohms. However, the output won't be as smooth as I would like to. Granted I can use lower values to smooth it out but I consider this to be a very "raw" or "primitive" solution. I've been thinking about a solution for the past few days and I would like to know your opinion or suggestions. Which would be the best path to take?
The mechanical solution wouldn't work because trimpots can't handle the current/power required to drive the gauge. Even a proper control pot wouldn't be adequate. Your best bet would be to use a power MOSFET as a voltage-variable resistor. You may be able to work out a PWM drive for the MOSFET to mimic the old resistive sensor, since the gauge will "average" the PWM result.
@@w2aew Thanks for answering! I actually tested the trimpot solution and it works with the gauge and that's because the gauge measures the resistance to ground. It has 3 wires: two for positive and negative (power) and the other is the signal wire (resistance relative to ground). And like I said the trimpot produces a very smooth output. I've heard about the mosfets as resistors and I will look into it. That's a opportunity to learn something new. I appreciate your help!
good day sir. I have "8A Automatic Adjustable Step Up Down Boost Buck Converter" and i want to replace trimpot with potentiometer ? how can i find the rating of the trimpot and what compatible rating of potentiometer and multi-turn potentiometer should i use?
You'll have to try to get the part number of the trimpot that is being used, either from the schematic, parts list, or from the part itself. Then, you would look up the ratings for that particular part from the manufacturer.
It's all about being careful about the power dissipation and the current through the wiper. Don't exceed the power dissipation rating, and make sure to keep the current through the wiper as low as possible.
Wow only 200 Cycles. That's where some of the trouble is I guess even if it's put there for calibration. Some equipment I work on need calibration a lot more often then one would think. Thank you
If I used a small trim pot in series with a resister could it be used for a precision adjustment of resistance to reduce DC OFFSET in a fixed bias stereo amp? My stereo is a fixed bias which is controlled by two HFE matched transistors and a tail resistor. In my case the tail resistor is a 10k but my DC OFFSET is 20 mv with no adjustment I would like to try to reduce this DC offset to as near zero as possible an maybe this could get me there. QUESTION: Where does the third lead attach or can it be left alone?
It is generally best practice, when using a trimpot as a variable resistor such as this, to connect the unused 3rd lead to the wiper. This will have no effect on the operation of the pot or the circuit under normal circumstances. In the case of a worn or dirty pot where the wiper contact goes "open", the overall resistance would only jump to the max value of the trimpot instead of jumping to infinity. This might be beneficial depending on the circuit design.
Can't say yes or no. Improper use of a trimmer can cause failure even at 1V. You'd have to check the datasheet for the particular trimmer you are using to get the voltage ratings, power ratings, wiper ratings, etc.
A bit surprising, would have expected a difference but not that great. I'm wondering how many 'microcents' are saved by applying a thinner layer? Anyway Alan, great little video, and if you are reading this, I wanted to ask if you ever made a video of different kinds of snubbers, like RC vs. diode when exactly to use which method? I find some info online, but also a fair bit of handwaving. Thanks for all your work, it has helped me alot and I recommend your channel often. :) - Kim
It depends. Sometimes you may get away with paralleling the ends of the pot, with a 1k resistor in this case - but it really depends on the circuit and how the pot is used which will determine if this works or not.
Great video as always! Thanks for sharing. I burned up many pots when I first began tinkering with my hobby projects! LOL. In future videos can you also discuss the different wiring configurations, wattage de-rating, and adding current limiting fixed resistors when using a pot as a variable resistor? Thanks!
I dont know how you are gonna receive this comment but, please keep making these videos. Helps out noobs like me a lot. I am thanksful
Thank you. Its good to know what kind of pots not to buy. Very usefull info. 👍
And here I was thinking "what can I possibly learn about pots"
Me too!
same. What a disappointment to us breaboard-ers to learn our favorite Trimmers/Trim-Pots/Presets is not a proper Potentiometers.
Thanks mate!
Excellent. Just the 2nd if your vids I've seen (1st was 15 min ago) and I'm loving it! I sub'd, hit the bell, selected all... looking forward to the rest!
The main page has an index of all my videos, might make it easier to search for a particular topic. Lower right corner of the banner graphic...
Another interesting and informative video! Keep them coming. Absolutely love your style of teaching - concise and easy to understand for a novice.
Alan, I've really missed your regular output in recent months but appreciate times and circumstances change and you focus on others interests. I always particularly enjoyed your 'back to basics' videos so it was really nice to enjoy one of these hugely informative sessions once again. We don't know each other but your videos have helped me so much over the years so a big thank you for all of them.
I appreciate your comments. The slowing down of video content creation on my end is not a reflection of any lack of interest, but just a lack of time. A lot of folks don't realize that each minute of published video content represents 10, 20, 30 minutes or more of total work on my end. So, a 10 minute video represents hours of work in many cases. I hope that I don't lose any loyal viewers like you simply because my "day job" is demanding more of my time.
@@w2aewYou'll never lose your loyal viewers as the reason is in the description...'loyal'. Very best regards and thanks for taking the time to explain.
Thanks, Allen! Something I "kinda knew," but never payed enough attention to. It explains why I was having so much trouble with my breadboard experiments the other night, and contact cleaner didn't seem to help the little trimmer!
This type of video make a big impact of me. Not to long but great knowledge about something I'll use and remember.
Another example of planned obsolescence that I was not aware of. Thanks for showing Alan!
I am so happy to see a new video notification from you !
wow never entered my head...... 200 cycles really? would be really cool to do a vid showing the demise of one or two of these guys
Just use one across a 1v DC supply, feeding the output into an AC coupled amplifier. Turn back and forth around 100 times end to end and they will get scratchy, especially if you leave them in one position for a few months as well.
Well, that was very interesting and useful advice. Thanks for sharing.
Guilty, as a hobbyist I've never heard of this and honestly can't say I've ever thought to opened a datasheet for a potentiometer until now... I guess it's one of those parts that's easy to take for granted because they're so inexpensive and are simple in terms of theory/operation.
Thanks for the great video!
thanks for sharing this, i am indeed a young player my self and im glad i watched this because i was going to use the the trim pot for the same use case as a rotary pot, i shall get some rotary pots and use them instead. I was going to use the trim ones because i had them laying around, but ill just get the rotary ones, thanks again for sharing.
I tend to use the trimmers in my initial circuit design but once I get a circuit I'm basically happy with I change to using a control pot, that way I get the right feel of the circuit before I build it up for proper.
Excellent video! Thank you for highlighting such hidden spec of a common part.
excellent video!
i never thought about that.... well, i usually only use use normal pots and i use trimmer pots where there is no place so, inside but really interesting and good to add to my knowledge! thanks again!!!!
Trap for young players, and some 50 something old ones!
i wish there was a type of system where we got a handful of chassis and a handful of pcb's with that resistor trace. that way when we burn out a pot, we can just swap the inside. also, then we could have better quality chassis. sure would fit in the bins better too. i have a couple thousand pots and they take up sooo much space !! could also swap values without unsoldering !!
Great tips on controls Alan.
Excellent breakdown of the variation out there + safety I know nothing of this stuff.
Thanks I was about to try to use one of those sparkfun trimmers for a crucial feedback placement that would have thousands of rotation cycles. I’ll be looking for something else now. Thank you.
Alan, great video. More videos like this one, please. Educating on things that are usually not even considered. Also, teaching on what to look on the datasheets. 73s
..and if used as a divider off of a voltage you can over-current and burn out a smaller pot.. not that they should have a lotta wattage, but I've seen pots burned on one side of the sweep. Also log vs. linear is worthy of note.
Reminds me of the very low quality experimenter kits from a once thriving electronics chain store , when I was in grade school 50 years ago. No rating at all. It discouraged many beginners. Thanks to a local electronics store that is still in business, sold quality commercial grade products. I still make a living in electronics. From circuit board repair to installing campus wide, fiber optic connected AV systems.
Good video, and I always knew that these trimmers aren't used for control but I'd never thought that they withstand just 400 turns, thanks for the great advice
Some are even less!
This is a good video. Thanks for your expertise and helping us avoid traps as young beginners.
Thanks Alan! It's easy to overlook the little things sometimes.
Very good point on a seemingly "no frills" part!
I didn’t know about those trim pots with knobs. Thanks.
Great and informative video Alan.
Another gotcha is pin arrangement. The same trimmer can have various pin arrangements indicated by a letter or number in the part number. The delta arranged pins can have a couple different spacings and won't fit the board if you order the wrong one.
As always very comprehensive..keep posting good stuff..could you kindly post topics on:
1.basic antennas, its characteristics, its measurements and best practices
2.differrent coax types and its applications
3. Stub matching
4. Antenna arrays
Thanks and best regards
This goes for switches too. If you check the data you can find some are rated for far more transitions than others. It's important to consider longevity when selecting parts.
Also, as someone else mentioned, it's easy to overload the small trimmer. It takes only a few volts across the trimmer to get too much current flowing and exceed the wattage rating.
Wow. I never would have thought... 200 vs 10000? Thanks a lot!
Thank You. I'm new into everything and I'm looking into building radios and other types of electronics and this is a great help.
More of these Back to Basic videos please and thanks….
Alan, good video. Even though I often think yeah I know that, it’s good to be reminded.
Good info!!! Would never had thought too check for this possible failing.
Funny, I think that I heard that anecdotally somewhere on TH-cam or during the ham radio classes that I took. Also watching when watching old ham radio repair videos all of those pots (resistors, capacitors and inductors) were so very touchy that I never imagined that they would have any real life expectancy other that a few settings.
Fantastically explained! Not a topic often covered, control vs. trimmer. Well done!
I’m so glad that I seen this video
Thanks
Good points covered! May also be good to do a followup video on "Taper" Linear, Audio, etc. Great videos :) Keep 'em coming.
Nice video. Would really like if you could also cover 4 terminal potentiometers (center tap). Also their application on volume and loudness controls. Thanks!
That's right they are a rarity this days nobody really uses them this days. So you might as well just use a normal logarithmic pot in audio with a little modification of the components around it Should work as a good as any.
Excellent review. Also it wasn't mentioned, but multi-turn pots and trimmers nearly always have a linear profile when plotting a change of resistance against a given amount of physical adjustment, whereas the single turn pots usually have an inverse-logrithmic profile for changes in resistance with respect to a given amount of physical adjustment. This is often referred to as a logrithmic tapre.
Single turn pots are available in BOTH linear and log taper - not all single-turn pots are log (most are linear in fact).
Speaking of trim pots. I recently found a good deal from an Ebay seller that had two new vertical attenuation modules for my old Tek 485. My channel 2 had a bad pot on the variable adjustment on the center of the volts per division rotary switch. The coupling switch also had something broken on it and didn’t lock in half the time. Long story short, I purchased it and it works like it should, only issue is when switching between voltage per division the trace jumps around on the 1 Meg input setting where it stays pretty static on channel one. The new module doesn’t jump around nearly as much as the old one, maybe within one graticule where the old module would jump half the screen. I deduct that there is some kind of balance adjustment because of the invert function on channel two? Just curious if you could give me a pointer on what trim pot to adjust? Found something in the manual that kind of gave an indication but not very in depth. I don’t have a service manual. Other than that the old girl works pretty good for a 40 year old scope I got for $50. The module was $55 lol. But it was worth it to have it working pretty much normal. I love it for testing and checking circuits in old tube amps. I like my cheap Rigol 1054z for all the measurements it has, but those old Tek scopes are like pieces of art inside. Thanks for all you do Alan.
Nice tech info, no more than I did before thank you
W2aew, can you explain more about the potentiometers "tapers" there is different taper curves like log, antilog, linear, etc. I'm not sure what to use as to graph chart a potentiometers taper maybe a curve tracer might work to test a pots taper type
100% Correct.
Just, If it is MADE IN CHINA, then the real cycle value should be the Square-Root....
Well presented. Thank you, it’s very helpful.
Thanks Alan, I would never have checked.
wow! i had no clue there is some rating like that!! THANKS A BUNCH!
Hey thanks for sharing this information!!
There is also the difference between an audio taper and a linear taper, which took me a long time to realize. Alan, thank you for all of your video efforts and for sharing your knowledge. I learned so much from you and am very grateful. Greetings from Arizona.
Please continue your back to basics videos.. at 67 I am teaching myself how to do electronics and your way of teaching is very good.. I can understand what your saying very well and am learning new things.. It is exciting! So carry on I have subed up and want to learn more.. I have visited your site and watched all the "back to basics".. I have always been interested in ham radio also.. But do not remember any of my morse code from the boy scouts.. Do they still require you to know it to get a license? that maybe my next project.. But down the road some... Thanks again.. I really appreciate you taking the time to do this..
Morse code proficiency is no longer a requirement to obtain a US Amateur Radio license at any level.
@@w2aew thanks.. one less thing to relearn...
Thanks sir, I am a new player and never considered pot endurance.
Glad to know that maybe this helped you avoid some future problems.
Good stuff. Moving parts are the usual suspects.
Some switches have this problem (low MTBF) too.
Yeah, especially those little DIP switches, often rated for 1000 cycles or less.
Thanks for this video. I bought a kit of guitar pots (On amazon of course... and regret it already) and it came with both kinds. I cannot figure out why they sent trimmers for a guitar building kit, as the pots need to be adjusted regularly, it makes no sense.
Love your videos!!!
Can you make one teaching the propper way to clean and lube faders?There are a bunch of videos but all of them or use non recomended cleanners for eletronics and usually they use some sort of grease or oil!!
In case of the faders wouldnt be better to use some sort of graphite or carbon to improove
conductibility?Also what can we do to "Tune" them!
Thank you for your videos,keep up the good work ;)
Have you ever tested the constant resistance of these things as the wiper moves?
This was quite enlightening. Thank you!
Its 3:20am here in UK W2AEW vid notification yay watching it dont care if its 2 hours long
I'm not Dave Jones, Shahriar, or Mr. Carlson - you'll typically not get many multi-hour videos out of me! ;-)
Unfortunately not! Thank you very much for the videos.
Great tip. I will definitely keep this in mind for the future. How about the max current rating? Is it usually higher for control pots than for trim pots, or is it most often about the same?
Yes, max current, particularly through the wiper, is generally higher for controls than trimmers. However, in both cases, it's best to try to design circuits that minimize wiper current if possible.
In the 1960s and 1970s there was a rule at Tektronix: thou shall not draw current through the wiper of a potentiometer! I still follow that rule.
I just knew I'd learn something in this video :)
Great video. I never even considered this. Ive gotta say though, I have some pots similar to the control pot you showed on Sparkfun and they're actually not that great for breadboards cuz they have those 2 metal tabs that stick out at the bottom. Even if you bend them up and out of the way, the pot never sits flush with the board. It's always at an angle. I usually just throw some female to male dupont connectors on them or just solder some wires on.
Always make sure to use SHIELDED CABLE and not wires on pots that are not mounted directly to the circuit board!
Wires won’t work at RF and even as low as audio frequency on certain projects I’ve done using wires on pots will cause the circuit to go nuts.
Hey Alan another great vid! cheers from Australia (not Austria)
sin't Austria part of Australia? The part without convicts?
This is awesome! I never thought about this. Thanks for sharing! 73, de KD7SJT
I actually always wondered why a capacitive variation is rarely being used, since you can basically have two floating sides, which means less wear over time. Especially with all these microcontrollers nowadays, but even with analog it's not to difficult to converter capacity to pwm to a voltage or something
Right on my friend. Your input is very much appreciated.
There's a lot to be said for digital trim pots and software support for multiple setting situations.
I have several microcontroller designs that have many trim pots that could benefit from this knowledge.
The break-even point has to be pretty low for your advice to be effective.
New sub. Great information. Happy to get good input.
Nice simple video! I have a request for a video on the input and output impedance of rf transistor circuits. I have found some brief and very general descriptions but very few sources go into what the actual impedance is and even fewer that do a good job of explaining why it is that impedance. Definitely not a back to basics video but I think it could help people understand rf designs much better if they knew why the matching networks are there on the input and the outputs. Maybe this would be a couple of videos? Thanks!
I'll add that topic to my long list of future video ideas...
Very interesting, thank you.
Hmm, good point Alan. I always hated those "gear" style trimmers since the screwdriver adjustment slot was always oriented vertically and invariably there was another component in the way forcing you to turn it manually...grrr; the trimpot with the knob would have been so much easier! Keep the basics videos coming, I always forward the link to our club's email reflector. 73 - Dino KL0S
Thanks for the information.
Good info as usual!
Great video! It's the reason I subscribed.
Great Video... Thanks you.
What is the difference between a line delay and phase shifter?
They both cause a delay, so from that standpoint they're pretty similar. However, a phase shifter is typically used for RF applications, often at a specific frequency, while a delay line could be more broadbanded.
w2aew oh thank you. I thought so. My friend asked me: why they dont use phase shifters in ultra-wide active phased array antennas and use line delay)
Why was no resistance mentioned though? Can a trimmer be substituted for a variable pot? Thanks
A trimmer is a variable pot - though designed for low power and infrequent use.
w2aew, thanks for replying, the first control pot you featured is the type of control I'm looking to use in my project. Is it possible to change a trimmer pot to a control pot by simply unsoldering the trimmer from its board. (In my case a buck boost converter). And soldering three wires to the controller? Your input would be helpful.
@@milvolts1 Yes, as long as they are the same resistance value.
Excellent tip! Thanks for sharing it with us. 73 de K7RMJ Frank
TNC for yet another great video !
73 N8AUM
I'm having a tough time getting an answer to this question. Can you tell me if there is a pot that can be turned left or right with the center being off? What I'm trying to achieve is,I have a pwm motor speed controller for my trolling motor. The way I have it set up is,I removed the trolling motor speed control drum switch that attaches to the end of the handle and replaced it with the b100k potentiometer that came with the controller. This works fine but to go in reverse,I have to use the rocker switch. An on off on rocker switch to be specific and have to turn the handle clockwise for both directions. It would be great if there is a pot that can be turned either way with the center being off. Preferably with a center detent. This way I could make it work in conjunction with the rocker switch. I'm thinking that I can make a sort of cam that would activate the rocker either way when the pot is turned with center being off. I would just like to be able to use it without having to use the rocker switch for both directions,just with the handle. Any info will be appreciated. Thanks.
Maybe something like a "balance potentiometer"
www.mouser.com/Passive-Components/Potentiometers-Trimmers-Rheostats/Potentiometers/_/N-9q0yi?P=1yx2jpt
@@w2aew I did order one of those today. I'm not sure how it will work as one side will have to be completely off before the other side turns on.
@@umpy3152 potentiometers don't have an "off" position, they're simply adjustable between minimum and maximum rated resistance.
@@w2aew The potentiometer that came with my pwm speed controller has an off position. When it's turned a the way to the left,it clicks off and shuts down the controller.
Minn kota has a couple variable speed trolling motors that use a 3 pin pot. Turn right for forward and left for reverse. The center is off. I own one of these but prefer the one I'm working on as it performs better than the minn kota. I actually took the pot off the minn kota and connected it to the other pwm but it did nothing. It must be set up to work with the minn kota control board only.
Can u Please recommend me to 10 turns with a knob very small sized potentiometer ?
Thank you for the information 🙏🏽🙌🏽
Can you do a video on how to read the values ?
In most cases where the connections are in a row - the pot value is read by reading the resistance across the outer two connections. If there is any doubt - measure the resistance across all three combinations - the largest value read will be the pot's value.
Thanks for making this video.
I actually have a question related to this topic. First, let me explain my project. I'm going to try to build a fuel meter system and I want to make the circuit as simple as possible even though I have to admit that I still consider myself a beginner.
To measure the fuel level I am going to use a pressure sensor. By the way, this is for a motorcycle. The sensor that I have gives voltage as an output (5 - 4v). And then I am planning on using an Arduino to process that data and send it to a fuel gauge. Here begins the challenge. The fuel gauge that I have takes in as input, resistance: 90 ohms or above = empty and 10 ohms = full.
The problem is that I was planning on using a digital potentiometer controlled by the Arduino to vary the resistance but unfortunately (at least from what I know) I could no find a digital pot that can output such a low resistance. Many of them are well over 5k. Maybe you know of some ICs that can do the job?
So I am left with two options:
1- Develop a mechanical solution which would be based on a stepper motor rotating a trimpot to obtain the desired resistance. I know this will give a very smooth output. But I really want to avoid taking this path because it would take up more space and I want to make my circuit without any moving parts. Let alone the added complexity.
2 - Use a group of staggered resistors to control the output. Maybe by increasing steps of 10 ohm resistors. It would be something like 10 - 20 - 30... until I get to 90 ohms. However, the output won't be as smooth as I would like to. Granted I can use lower values to smooth it out but I consider this to be a very "raw" or "primitive" solution.
I've been thinking about a solution for the past few days and I would like to know your opinion or suggestions. Which would be the best path to take?
The mechanical solution wouldn't work because trimpots can't handle the current/power required to drive the gauge. Even a proper control pot wouldn't be adequate. Your best bet would be to use a power MOSFET as a voltage-variable resistor. You may be able to work out a PWM drive for the MOSFET to mimic the old resistive sensor, since the gauge will "average" the PWM result.
@@w2aew Thanks for answering!
I actually tested the trimpot solution and it works with the gauge and that's because the gauge measures the resistance to ground. It has 3 wires: two for positive and negative (power) and the other is the signal wire (resistance relative to ground). And like I said the trimpot produces a very smooth output. I've heard about the mosfets as resistors and I will look into it. That's a opportunity to learn something new.
I appreciate your help!
@Undefined Lastname Thanks, I will check that.
good day sir. I have "8A Automatic Adjustable Step Up Down Boost Buck Converter" and i want to replace trimpot with potentiometer ? how can i find the rating of the trimpot and what compatible rating of potentiometer and multi-turn potentiometer should i use?
You'll have to try to get the part number of the trimpot that is being used, either from the schematic, parts list, or from the part itself. Then, you would look up the ratings for that particular part from the manufacturer.
@W2aew Please tell me how do I include a potentiometer in my projects without frying it?
It's all about being careful about the power dissipation and the current through the wiper. Don't exceed the power dissipation rating, and make sure to keep the current through the wiper as low as possible.
Wow only 200 Cycles. That's where some of the trouble is I guess even if it's put there for calibration. Some equipment I work on need calibration a lot more often then one would think. Thank you
Hello, I am replacing a 20K pot from a cassette tape deck. It has a center position tap/ click. Do all type 'B' pot's have center tap ?
No, I don't believe that they do.
If I used a small trim pot in series with a resister could it be used for a precision adjustment of resistance to reduce DC OFFSET in a fixed bias stereo amp? My stereo is a fixed bias which is controlled by two HFE matched transistors and a tail resistor. In my case the tail resistor is a 10k but my DC OFFSET is 20 mv with no adjustment I would like to try to reduce this DC offset to as near zero as possible an maybe this could get me there. QUESTION: Where does the third lead attach or can it be left alone?
It is generally best practice, when using a trimpot as a variable resistor such as this, to connect the unused 3rd lead to the wiper. This will have no effect on the operation of the pot or the circuit under normal circumstances. In the case of a worn or dirty pot where the wiper contact goes "open", the overall resistance would only jump to the max value of the trimpot instead of jumping to infinity. This might be beneficial depending on the circuit design.
Can someone tells me what time in this video I will see oscilloscope as always? I can't find it.
Can i replace a W103 por with 10k potentio meter which we use as volume control in radio? i mean 10K linear or log?
if i work with 0-30 voltage will most of the trimmers stand it?
Can't say yes or no. Improper use of a trimmer can cause failure even at 1V. You'd have to check the datasheet for the particular trimmer you are using to get the voltage ratings, power ratings, wiper ratings, etc.
Tnx for the great advice. 👍
A bit surprising, would have expected a difference but not that great. I'm wondering how many 'microcents' are saved by applying a thinner layer? Anyway Alan, great little video, and if you are reading this, I wanted to ask if you ever made a video of different kinds of snubbers, like RC vs. diode when exactly to use which method? I find some info online, but also a fair bit of handwaving. Thanks for all your work, it has helped me alot and I recommend your channel often. :) - Kim
I've only made one talking about flyback (snubber) diodes around relay coils, etc., but none that talk about RC snubbers.
Is there anyway to decrease resistance 1k potentiomter to 500ohms pots?
It depends. Sometimes you may get away with paralleling the ends of the pot, with a 1k resistor in this case - but it really depends on the circuit and how the pot is used which will determine if this works or not.
Thx ill see what can i do
Nidec Copal CT9EW104 18 Turn Precision also has 200 cycles.
Great video as always! Thanks for sharing. I burned up many pots when I first began tinkering with my hobby projects! LOL. In future videos can you also discuss the different wiring configurations, wattage de-rating, and adding current limiting fixed resistors when using a pot as a variable resistor? Thanks!
it reminds me of the controls on teenage engineering stuff
"teenage engineering" - what an appropriate name...!