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Budget multimeter recommendations?
Not wanting to necro watercooled thread from 9 years ago and wanting to have a feature that I'm not sure comes with all multimeters I'm putting my trust in you guys and girls. :) The extra feature I'm looking for, beyond what i assume is typical, is measuring a PWM signal, would i be right in saying that's frequency.
I watched the video linked in the above thread from EEVblog and as a hobbyist i got a bit lost and it's from 10 years ago so I'm not sure how relevant it still is, what would be great is if someone could say buy this, it's under £50, you can use it to measures a PWM signal and most other DIY jobs around the house.
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Re: Budget multimeter recommendations?
signing in as interested too. I ended up buying a lamptron sm436 fan controller to monitor pwm or rather convert it to rpm for me. I power it off a standalone DC supply via some crocodile leads into a molex cable.
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Re: Budget multimeter recommendations?
I remember a while back checking Ebay,and found a pair of Brymen ones really cheaply.It appears people were after more famous brands like Fluke(which are fantastic),so you just need to do some research. EEVBlog YT channel and website is a good place to start(Brymen was one of the brands mentioned).
If you want to spend less,its worth checking out their forums too:
https://www.eevblog.com/forum/beginn...-i-should-buy/
https://www.eevblog.com/forum/review...d-multimeters/
Its a treasure trove of information.
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Re: Budget multimeter recommendations?
FWIW my mutlimeter is a Aidetek VC99+ and it's great (and affordable). I've just noticed it has a Hz setting, not sure if that will check pwm pulsing for rpm, however I have hooked it up to the lamptron to log the DC volts and it does seem to show the average V when the unit is supplying pwm signal to the fan. You get a bit of a drift +/-0.5V but it's easy enough to work out the net average.
I can't see it on there anymore but this one looks nigh-on identical: https://www.amazon.co.uk/Auto-Rangin...dp/B00EYYJRC0/
Give me the evening and I'll have a play re the pwm/rpm side of things. Not sure if it will play ball only having one lead connected though to the pwm header pin. Maybe the 2nd lead just needs to go to ground idk?
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Re: Budget multimeter recommendations?
IDK know they had a forum too, thanks Cat. :)
Quote:
Originally Posted by
ik9000
FWIW my mutlimeter is a Aidetek VC99+ and it's great (and affordable). I've just noticed it has a Hz setting, not sure if that will check pwm pulsing for rpm, however I have hooked it up to the lamptron to log the DC volts and it does seem to show the average V when the unit is supplying pwm signal to the fan. You get a bit of a drift +/-0.5V but it's easy enough to work out the net average.
I can't see it on there anymore but this one looks nigh-on identical:
https://www.amazon.co.uk/Auto-Rangin...dp/B00EYYJRC0/
Give me the evening and I'll have a play re the pwm/rpm side of things. Not sure if it will play ball only having one lead connected though to the pwm header pin. Maybe the 2nd lead just needs to go to ground idk?
Thanks for the link, I'd be the worse person to ask about if it needs a GND, i guarantee i know less than you.
I'll probably buy one and blow myself up within a week. ;)
EDIT: So having educated myself a bit more i was thinking it maybe better spending a bit more to get an oscilloscope multimeter, I'm not entirely sure though, what's peoples thoughts on this? https://www.amazon.co.uk/Digital-Osc.../dp/B07YSNFRVM
2nd EDIT: I've done what i always do when trying to learn about something, I've ended up totally confusing myself. :(
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Re: Budget multimeter recommendations?
https://www.amazon.co.uk/Neoteck-Mul...2&s=diy&sr=1-3
That one looks OK to me, Id buy one if I needed the functions you mentioned, 100Hz FS up to 30MHz :) Nice.
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Re: Budget multimeter recommendations?
What are you trying to do with PWM?
If you want to check duty cycle, then you probably do want a 'scope not a multimeter. Just checking frequency of a PWM signals isn't generally that useful.
Edit: That scope multimeter looks pretty slow, so it might work for very low frequency PWM signals for things like servo or motor drive but any high frequency PWM outputs it probably won't see.
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Re: Budget multimeter recommendations?
The intention was to check what i suspect maybe some fake PWM headers on a motherboard and then keep it around for general DIY stuff in the future. However after having spent the last couple of days reading it seems i underestimated how complex (at least for me) such a thing is, I'm thinking i maybe better off getting a multimeter like the one g8ina and ik9000 kindly linked to and then a separate cheap'o scope, i was looking at those DIY scopes like the Kuman DSO 138 as it would make for a nice project/practice but I'm not entirely sure if probing a 12v PWM header would be too much for it as I'm not entirely sure what some of the specs mean, like does 5V/Div mean it can only measure up to 5v or that each line/division on the screen would be 5v so with 10 lines you'd have a 25v +/- range.
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Re: Budget multimeter recommendations?
that oscilloscope you linked to isn't very good. The reviews point out you can't adjust the frequency axis in the display which is kind of important for viewing waveforms IMO. You're better off getting a bench unit if you can't find a handheld that lets you do that.
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Re: Budget multimeter recommendations?
Yea i wasn't expecting it to be at that price. :) I wish my level of understand was enough to know why I'd want to know the frequency, i wasn't expecting what seemed like such a simple thing (those pretty plots of waveforms) to be so complex, I'm feeling a bit like I've fallen down a rabbit hole.
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Re: Budget multimeter recommendations?
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Re: Budget multimeter recommendations?
From a quick Google, if all you want to look at is PC fan headers then they only work at around 25KHz. That's unfortunate, as it's just a bit too high to be able to slap a couple of resistors across it and feed it into a sound card line input.
Still, in 'scope terms 25KHz is nothing. For a simple visual "Yeah, that's a PWM signal" you could get away with sampling at 10 times higher, so that cheap multimeter scope you linked earlier that samples at 200KHz is just capable.
I note looking at it there is a setting for "Frequency/Duty Cycle" so it looks like it will even try and tell you what percentage of drive the fan is getting.
The frequency measurement should also be handy for measuring fan tacho pulses being sent back from a PWM fan.
So that looks like it would fit the bill, or at least something like it given it says on the page it would turn up some time in March so I guess that is arriving direct from China.
Quote:
Originally Posted by
Corky34
, like does 5V/Div mean it can only measure up to 5v or that each line/division on the screen would be 5v so with 10 lines you'd have a 25v +/- range.
You read it like graph paper, so 5V per division means 10 divisions is 50V. One of the dials on a traditional scope is a Y offset, so you can decide which division is 0V allowing you to do ac or dc waveforms.
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Re: Budget multimeter recommendations?
A lot of the handheld cheap oscilloscopes I looked at the other day don't appear to allow offsetting the Y axis nor altering the axis scales independently (to expand frequency scale for example)
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
g8ina
That's a bit more than i was hoping to spend, it was only a couple of days ago that i thought £50 would get me a DMM with the ability to see if a PWM fan header is actually using PWM or cheating by lowering the voltage.
Quote:
Originally Posted by
ik9000
A lot of the handheld cheap oscilloscopes I looked at the other day don't appear to allow offsetting the Y axis nor altering the axis scales independently (to expand frequency scale for example)
Embarrassingly i wish i knew why i would or would not want that, even though I've spent the last couple of days reading up i still feel like an idiot.
I'm very much a learn by doing sort of person so I'm going to buy the VC99 you linked to earlier and the updated model of the DSO138, when it's in stock in the UK that is because not knowing if i had to pay import fees would trigger my anxiety, that way i can learn how to use a DMM and practice soldering while i build the DSO and not have to worry to much if i get something wrong.
So grateful for everyone's input, wasn't looking forward to second guessing myself for weeks. :) :hexlub:
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
Corky34
The intention was to check what i suspect maybe some fake PWM headers on a motherboard and then keep it around for general DIY stuff in the future. However after having spent the last couple of days reading it seems i underestimated how complex (at least for me) such a thing is,
Reading this thread has been a little painful...For the record, before I sidestepped into IT I was in electronics production and test, beginning with a year of work experience in the GEC calibration labs. That was 30 years ago but I have tried to keep my hand in, so to speak.
PWM is not difficult but you do need a good understanding of Ohm's law and the maths that underlies it. V / I x R, P = I x V
In analogue DC circuits power (P) is controlled continuously by adjusting resistance (R). Voltage is generally assumed to be fixed, so an increase in R reduces current (I) and P also reduces. In the digital domain, R doesn't exist and V can only be on or off. To control P in the digital domain, I is chopped up by rapidly switching V. By adjusting the ratio of Von to Voff within a fixed time-frame (PWM), the average of P is varied over some longer time frame. The rest comes down to design decisions and interfacing electronics.
PWM frequency refers to the length of the time frame, similar to a sample period. PWM duty-cycle refers to the ratio of Von to Voff within the time frame, expressed as a percentage. Only the duty cycle controls power. A 50% duty cycle at 1Hz causes current to be available for 500 milliseconds every second. Increase the frequency to 1KHz and you have 1000x more pulses but the total of Von time over one second is still 500 milliseconds. A 100% duty cycle yields the supply voltage and an effective PWM frequency of 0Hz.
You don't need a special meter to read PWM duty cycle. Any *True RMS* meter with an *AC* range will do but some simple maths is needed to convert the measured voltage to a percentage of the supply voltage resulting in the duty cycle. A % key on the DMM saves doing the maths yourself. The DMM is not measuring the length of the duty cycle but rather measuring the supply voltage and working backwards.
The PWM frequency is a design decision and selected to avoid unwanted artefacts from the D2A conversion. PWM frequencies for dimming LEDs can be as low as 20Hz (20ms) but 120Hz (8ms) is less likely to produce a noticeable flicker. Chassis fan PWM frequencies are typically around 25KHz to avoid creating electrical and audible noise in the sonic spectrum (20Hz to 20Khz).
You can't just poke probes at an open PWM pin and expect to see something useful - You have to read the interface spec and meet the requirements for pull up / pull down and decoupling Etc.
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I'm thinking i maybe better off getting a multimeter like the one g8ina and ik9000 kindly linked to
Buying advice in part 2.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
matts-uk
Reading this thread has been a little painful...
You can't just poke probes at an open PWM pin and expect to see something useful - You have to read the interface spec and meet the requirements for pull up / pull down and decoupling Etc.
Sorry, i guess that's what happens when a luddite like me doesn't know what they're talking about. :Oops: :embarrassed:
It's very much appreciated that you've taken the time to write a proper explanation as I'll undoubtedly come back and re-read it when the doing/practice makes something click in my brain, probably doesn't help that maths doesn't come naturally to me and even things like Ohm's law is just a word to me ATM. :) I may not even be able to workout what i set out to due to ITE not publishing the specs of the controllers so I'm guessing i won't know what the requirements for pull up / pull down and decoupling Etc are, I'm OK with that if I'm honest as it's become about learning more about the things all you guys have talked about.
That's why i prefered the DIY kit thing as it will give me a chance to learn as i go and due to it being partially open source and cheap i can try/confirm things without the worry of turning £50+ into blue smoke. :)
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
matts-uk
You can't just poke probes at an open PWM pin and expect to see something useful - You have to read the interface spec and meet the requirements for pull up / pull down and decoupling Etc.
There is a lot of glossing over of details going on for my part, but this is something that I meant to say and it did get omitted.
A decent modern motherboard will only output a PWM signal if it detects a PWM capable fan. I would try and grab a 4 pin extension cable to make measurements easier, but you probably need a fan plugged in to see anything. A circuit to fake there being a fan connected would cost more to make than cheap fan :)
In that circumstance, I would totally expect to be able to see the PWM signal even on one of those cheap multimeters. He isn't talking about detailed duty cycle measurement here, just a basic "is this actually PWM" which should be pretty obvious compared to a DC fan control with just the voltage varying.
Quote:
Originally Posted by
Corky34
I'm very much a learn by doing sort of person so I'm going to buy the VC99 you linked to earlier and the
updated model of the DSO138, when it's in stock in the UK that is because not knowing if i had to pay import fees would trigger my anxiety, that way i can learn how to use a DMM and practice soldering while i build the DSO and not have to worry to much if i get something wrong.
That DMM says it can do frequency and duty cycle measurement, in which case it should be able to tell you what's going on, or at least I expect I could work out what it is doing with that but I'm not sure how clear it would be to a beginner. It looks a useful bit of kit regardless.
That diy scope still looks rather toy like. Having some sort of 'scope is really nice though, nothing beats being able to actually see the waveforms coming out, specially if a circuit was designed by someone like me where I have used some pretty whacky waveforms for driving things like LEDs because I ran out of hardware timers and had to drive off a 1KHz interrupt in software, but it saved a few pence doing it that way which adds up when you sell a million units :D
If you want something that could be genuinely useful in the future, you sadly need to spend proper money, something like this:
https://uk.farnell.com/multicomp-pro...sps/dp/3107575
where a PC does the display and user input bits, so you are only paying for measurement electronics. at work we use similar Picoscope kit, I think we only have one "proper" scope with a display on it.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
Corky34
Sorry, i guess that's what happens when a luddite like me doesn't know what they're talking about. :Oops: :embarrassed:
No need to apologise, I doubt you are a luddite and the only thing to be embarrassed about is the expectation. An electronics degree is 5 years. I took a more vocational route but it was still 18 months of education and lab work to prepare for the work placement. I merely scratched the surface. I wasn't an expert then and I am not one now.
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]It's very much appreciated that you've taken the time to write a proper explanation as I'll undoubtedly come back and re-read it when the doing/practice makes something click in my brain, probably doesn't help that maths doesn't come naturally to me and even things like Ohm's law is just a word to me ATM. :)
Hmm. Yes. I hear stuff like that every time I take on a new technician. Generally they take longer getting over their adversity to doing maths than doing the maths. Poking around with electronics without a grasp of Ohm's law is like attempting to drive a car without first learning where the accelerator, clutch and brake are, and the relationship between them - I guess it's possible but it sounds painful and expensive to me ;)
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I may not even be able to workout what i set out to due to ITE not publishing the specs of the controllers so I'm guessing i won't know what the requirements for pull up / pull down and decoupling Etc are, I'm OK with that if I'm honest as it's become about learning more about the things all you guys have talked about.
It's easier to learn about 'the things' from first principles. Start with simple circuits and build on that. You can have a lot of fun with an Arduino and a handful of resistors and LEDs at pocket money prices. I mean there's a bit of maths but it doesn't have to be boring.
Take the time to do the background work and you don't need the ITE data-sheet either. I can point you at the materials but it's up to you to read them.
Step 1. How is it supposed to work and why?
https://www.analog.com/en/analog-dia...an-speed.html#
Step 2. Find similar schematics
Scroll down to Figure 7 in the Analogue Devices document.
The motherboard will look similar to this.
https://www.electroschematics.com/wp...tor-Scheme.png
Ref: https://www.electroschematics.com/4-wire-pc-fan/
There is a salutary tale in the second link ;)
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That's why i prefered the DIY kit thing as it will give me a chance to learn as i go and due to it being partially open source and cheap i can try/confirm things without the worry of turning £50+ into blue smoke. :)
So buying advice.
The VC99 is made by Vichy and sold under many different names. Typical Chinese OEM stuff, looks better on the outside than it is on the inside. It will do the job but don't expect it to last. I wouldn't be brave enough to test the safety rating by poking at a mains supply though. Personally I wouldn't bother with the Vichy. I would put the money towards a known brand with a reputation to worry about. For a beginner, I'm thinking Uni-T. Another Chinese manufacturer but they have been around since 1988 and include a cal cert in the box. Uni-T are like the Draper tools of measurement instruments. You get a lot for your money and the quality is not that bad. If you don't mind a discontinued model the UT61D is a legend of a hobbyist DMM. Comprehensive package of useful features, with RS232 output and freely downloadable software for data-logging and scope-a-like charting. About £50 on e-bay from Lithuania or China.
The pocket scopes get a bashing, quite deservedly, but are not entirely useless. I have one I use for the odd sanity check. Easier than pulling out my full size DSO, less risk of electrocution and at £20 I am not going to cry if I blow it up. It helps to know the limitations as those limitations can make a perfectly fine signal appear screwed up. You would be better buying a ready assembled example IMHO. If you build it and it doesn't work when you switch it on, what are you going to use to fault find? Soldering practice is best done with some strip board and a handful of resistors and LEDs.
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Re: Budget multimeter recommendations?
I've tested the mains with my VC99 (and a plug probe converter). Worked fine. I've tested numerous guitar+amp+pedal+psu electronics and it's been fine. It's not a fluke and I wouldn't use it in a lab/for military contracts etc but it is fine for the amateur hobbyist as a starting point. I wouldn't push the OP to splash more money than they need to when they clearly are just putting their toe in the water so to speak.
@OP a great textbook if you have a basic physics background under your belt already (and tbh even if you haven't) is Practical Electronics for Inventors by Paul Scherz and Simon Monk (Mcgraw Hill). I have the 3rd edition in print and 4th ed on kindle. 4th is much the same but some comments about thinner paper in the print edition. It goes from the basics very well, and better than my uni lecturer did tbh!
Now on the fans themselves. Had a spare 5 minutes last night:
I tried seeing what the vc99 would come up with measuring the tach and pwm pins. Akasa fans tach measured the fan rpm (albeit in 2xHz) (46Hz reading is 2x23Hz as presumably double pulse per revolution due to the split coil) but Noctua fans same tehnique spat out 2kHz so no idea what's going on there, and indeed whether the akasa fan was a fluke or whether the Noctua uses a different system (and therefore how the same header can control the two different types so readily), (both were pwm fans).
I need more time to play with the pwm as I only played with 100% which obviously won't be doing any pulsing. I agree with others' comments it's probably not the best way to try and measure fan behaviour, and hence I also use that Lamptron board I mentioned to do my checking of what's going on, but it should be able to detect something from the pwm pin. Whether that is of any use remains to be seen!
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
DanceswithUnix
A decent modern motherboard will only output a PWM signal if it detects a PWM capable fan. I would try and grab a 4 pin extension cable to make measurements easier, but you probably need a fan plugged in to see anything. A circuit to fake there being a fan connected would cost more to make than cheap fan :)
'Detect' sounds too grand. The PWM signal drives a FET. Without some bias on the line you are going to see jack all. Faking the PWM input can be done with a couple resistors. Let's be generous and call it £1.
The learning point is the meter needs to be in parallel. A breakout is ideal. Alternatively, the PCB header is usually long enough to get a hook or bent wire under the connector but care is needed to avoid a short.
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In that circumstance, I would totally expect to be able to see the PWM signal even on one of those cheap multimeters. He isn't talking about detailed duty cycle measurement here, just a basic "is this actually PWM" which should be pretty obvious compared to a DC fan control with just the voltage varying.
For a functional test you need any old meter that will read +12V DC - My car battery charger would do.
If the fan runs at less than full speed with +12V on the Yellow wire, it's PWM.
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That DMM says it can do frequency and duty cycle measurement, in which case it should be able to tell you what's going on, or at least I expect I could work out what it is doing with that but I'm not sure how clear i would be to a beginner. It looks a useful bit of kit regardless.
I'm still smirking at a 30Mhz frequency range on a 4000 count no-name Chinese meter - More aspiration than specification :D
PWM frequency measurement can be misleading. As I said, 100% duty cycle will read 0Hz and the supply voltage, exactly the same as a dumb fan. Maybe the reading isn't 0 or the PWM frequency, is that a fault? The unexpected reading can be caused by a DMM not being suited to frequency counting - The lack of a trigger control gives it away. The % (duty cycle) key can be misleading too. My understanding of the spec is the PWM signal is sometimes inverted (active low).
Owning test equipment is not enough. You need to know what you are measuring and how the test can influence the result.
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I have used some pretty whacky waveforms for driving things like LEDs because I ran out of hardware timers and had to drive off a 1KHz interrupt in software, but it saved a few pence doing it that way which adds up when you sell a million units :D
Did you plonk an LED on the end of the interrupt pin and expect there to be enough current? I'm guessing not.
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If you want something that could be genuinely useful in the future, you sadly need to spend proper money, something like this:
In my experience owning a similar pocket scope, a surprisingly useful toy for £20. I bought mine as a stop gap when my old CRT bit the dust. The original firmware needed binning but after flashing BenF-Waves it's been OK. You wouldn't want to measure anything with it but as a glorified logic probe, yeah, it's cute.
Quote:
...at work we use similar Picoscope kit, I think we only have one "proper" scope with a display on it.
If you only had one scope, which would it be, PC or stand-alone?
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Re: Budget multimeter recommendations?
Gentlemen, from me, thank you.
Thank you to Corky34 for asking the questions and Matt, Ik, Cat, Dances et al for answering without being condescending or biased.
For me, it is why I like Hexus
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
ik9000
...but Noctua fans same tehnique spat out 2kHz so no idea what's going on there...
Funny that you should mention Noctua as their new A12x25 PWMs are what started all this, well that and Gigabyte motherboards, apparently they don't play well together which kind of sucks when you discover that a year after buying 4 of them.
As it doesn't seem to be something Gigabyte is ever going to fix and i can't update the fans i thought, maybe foolishly, that if i learnt about electronics there's a remote chance of doing something about the fans stopping when going under 1000 x rpm and if not I'll at least have a chance to learn something along the way. Also a coincidence that matts-uk has mentioned the Arduino as in all the reading I've been doing I've seen it mentioned a few times so thought I'd read up on that before bed. :)
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
Corky34
Funny that you should mention Noctua as their new A12x25 PWMs are what started all this, well that and Gigabyte motherboards,
apparently they don't play well together which kind of sucks when you discover that a year after buying 4 of them.
As it doesn't seem to be something Gigabyte is ever going to fix and i can't update the fans i thought, maybe foolishly, that if i learnt about electronics there's a remote chance of doing something about the fans stopping when going under 1000 x rpm and if not I'll at least have a chance to learn something along the way. Also a coincidence that matts-uk has mentioned the Arduino as in all the reading I've been doing I've seen it mentioned a few times so thought I'd read up on that before bed. :)
I bought two of the slimline ones and had PWM issues with my Asus motherboard trying to run two off a splitter. Both would work,and then randomly one would stop. I was not sure whether the splitter was the issue,but I am sure they worked with some other fans I had. Must check and see if the single one I have is working correctly too.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
Corky34
Funny that you should mention Noctua as their new A12x25 PWMs are what started all this, well that and Gigabyte motherboards,
apparently they don't play well together which kind of sucks when you discover that a year after buying 4 of them.
As it doesn't seem to be something Gigabyte is ever going to fix and i can't update the fans i thought, maybe foolishly, that if i learnt about electronics there's a remote chance of doing something about the fans stopping when going under 1000 x rpm and if not I'll at least have a chance to learn something along the way. Also a coincidence that matts-uk has mentioned the Arduino as in all the reading I've been doing I've seen it mentioned a few times so thought I'd read up on that before bed. :)
Wait, so what is the issue? Your fan is stopping, or you want to make it stop?
From a previous post you suspect the mobo has fake pwm 4-pin header that you think isn't doing pwm. That is an easy check with a Y cable and a multimeter.
1)1 buy some of these:
https://www.amazon.co.uk/Elegoo-120p.../dp/B01EV70C78
2)peel of some of the male-female ones and you can plug those to the fan Y cable header, and use crocodile clips onto the male end from your multimeter set to DC volts.
3) connect the two left-most pins (yellow and black cables) and see what happens to the DC voltage as the fan speed is adjusted. For a pwm fan the voltage should be constant (12V) across those two pins. If not then it's changing the fan voltage via conventional 3-pin method.
Now if the fan is cutting out below 1000rpm (how are you confirming the rpm btw?) That fan according to Noctua has a min speed of 450rpm. If it is receiving pwm duty below what it needs for 450rpm it will stop. If you want to make it stop below 1000rpm then you can configure it in the mobo uefi usually or using fan control software along with setting the temp you want the fan to spin up at. I wouldn't do that for a cpu fan but for certain case fans sure I can see a case (if you pardon the pun).
How many fans are you using from the header? Just one at a time or are you using the fan on a Y-cable or larger splitter? What current rating does the header have?
The noctua nf-a12x25-pwm only has 0.14A draw so well within most headers. Which other fans are on the splitter? Do they all have the same current draw?
I have played with the 140mm Noctua NF-A15 PWM and NF-A14 PWM as well as the Chromax NF-A15 HS PWM and they all respond to voltage control. At 100% they are 1620rpm, at 40% pwm they are at 960rpm. My pwm controller limits it there and jumps to 0% to prevent weird stuff. However muggins here hooked them up to a voltage controller for giggles. Here's how they behave using 100% pwm and changing the voltage supply:
12V 1620 rpm
11.5V 1560rpm
11V 1500rpm
10V 1380
9V 1260
8V 1140
7V 1020
6V 900 and the limit of my little asetek fan controller. FWIW 600rpm is practically silent - I mean stick your ear next to it barely a sound, and inside a case you're not hearing it.
I now stick in some resistors (totalling 45ohm in series)
5.5V 820rpm
5V 720
4.6V 660
at this point I think, ok throw in some more resistance.
Swap out the previous ones, add in 200ohms in series the fan wouldn't turn on. Not enough juice to get itself spinning. cranking the asetek dial back to max saw the fan grumble and kind of try but it was not happy and I just took the 2nd resistor out.
Now with 100ohm in series (roughly the same as the fan's internal resistance)
weird stuff happens. The lamptron logs the fan going right down to 240rpm (and visually it is definitely spinning a lot slower) but the multimeter voltage reading is jumping all over the place from 4.6 to 6V constantly, not settling at all. The multimeter is not the issue - it can definitely handle that low voltage range, and with the fan being slower the supply voltage should now be well below the range it keeps reading as. It's almost like the fan has suddenly started doing its own pwm! Either the fan is now slow enough for the coil switching to be giving some weird ac effects back to the multimeter (I really don't think it should be) or alternatively the asetek controller is fighting the current sag, but then I'd expect the fan speed not to reduce like it does. The supply current at source is rising but only from 0.3A to 0.32A so I'd be surprised if it's that. I'll see if I can rig up a separate 12V supply to run the lamptron display and just use my power source to drop the supply V to the fan right down in isolation and take the asetek controller out of the loop. Having worked out the circuit for the asetek it's not a simple voltage divider, it's using a voltage regulator transistor so could be interfering. I'll see if the DMM plays better in AC rms mode.
TLDR? The 140mm version will definitely go down well below 1000rpm however.
The point I'm trying to get to is if your UEFI is like mine you can set that fan in the BIOS to be a traditional (non PWM) fan and run it that way. It should behave just fine going by my tests on its larger sibling.
Quote:
Originally Posted by
CAT-THE-FIFTH
I bought two of the slimline ones and had PWM issues with my Asus motherboard trying to run two off a splitter. Both would work,and then randomly one would stop. I was not sure whether the splitter was the issue,but I am sure they worked with some other fans I had. Must check and see if the single one I have is working correctly too.
If an old board it's possible that might be a current supply thing though most headers can handle at least two fans these days, usually three or four.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
ik9000
If an old board it's possible that might be a current supply thing though most headers can handle at least two fans these days, usually three or four.
Its an Asus Strix B450I mini-ITX motherboard.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
CAT-THE-FIFTH
Its an Asus Strix B450I mini-ITX motherboard.
where are the fans in the case cat? Is one of them getting interference from another fan, say the cpu fan or similar that might be helping one keep going while the other struggles?
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
ik9000
Wait, so what is the issue? Your fan is stopping, or you want to make it stop?
The point I'm trying to get to is if your UEFI is like mine you can set that fan in the BIOS to be a traditional (non PWM) fan and run it that way. It should behave just fine going by my tests on its larger sibling.
:)
It's that they stop, well sort of, even when no stop is set in the BIOS. Between 25(ish)% and 35(ish)% PWM set in the BIOS they'll spin on first boot then a reboot, sleep or just falling bellow 1000rpm for to long and they'll stop spinning and go into a "I'm about to spin", "No I'm not", sort of jitter. Like they're getting a kick of voltage but only 1 kick per second. The slowest they go when the BIOS is set to voltage is around 850rpm so that's what I'm using ATM.
They do that when connected directly to a header (1x1) or when there's two running through a splitter, it's also worth noting that this only happens with their new A12x25, the ones with more blades that look a bit like gentle typhoon's.
The rpm is being taken from what the motherboard control chip is reporting, well when it's not jumping around from reporting 0rpm to 1000rpm to 4000rpm every second.
I assume the headers have the standard 1amp rating but Gigabyte being Gigabyte (it's one of their X570's) they don't actual say what amperage they're capable of, either way I've tried them on both fan and fan/pump headers (that i assume are higher amperage), no difference.
RE: Your 1, 2, 3 trouble shooting steps that's sort of what i intended to do, at least something similar, basically watching what happens by taking measurements using a spare Y splitter.
This isn't the only reason i wanted a DMM and a play around with a DIY scope BTW, i maybe stupid when it comes to electronics but I'm not crazy, I'm just getting there is all. ;)
Since fixing an old monitor a while back I've always wanted one and to understand electronics/electrics more than my typical sweat inducing that shouldn't be live because it's switched off or I've pulled the breaker but I'm not entirely sure, lets touch it and find out approach.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
matts-uk
'Detect' sounds too grand.
Really? It can vary voltage and PWM and check the tacho pulse return to see what works, with some careful finesse to check whether PWM works before you attempt voltage control as voltage controlling a big 140mm or bigger fan will likely blow the motherboard header.
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Did you plonk an LED on the end of the interrupt pin and expect there to be enough current? I'm guessing not.
I don't know what you are trying to get at there, but many microcontrollers are rated for direct LED drive (as long as you are sinking current, not sourcing). In that case though I think we were driving three LEDs from one pin, so we buffered it with a transistor.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
Corky34
The rpm is being taken from what the motherboard control chip is reporting, well when it's not jumping around from reporting 0rpm to 1000rpm to 4000rpm every second.
That doesn't sound good :)
I'm glad you have said what the actual problem is though, it should make it somewhat easier to help. The thing is, 4 pin PWM headers are cheaper for the motherboard, so there isn't any reason to "fake" it. OFC that doesn't mean someone hasn't faked it for some bizarre reason, but it seems more likely to me that they simply messed up with their fan control and what you are looking at is just a bug in their control system.
Is it possible to set the BIOS to forced PWM rather than voltage control, and set a fixed fan speed which is fast enough to keep the CPU cool without being deafening? I'm not saying to use that as a long term solution, just wondering if avoiding all the fancy PID fan control logic and driving it old skool would give a stable fan speed.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
DanceswithUnix
voltage controlling a big 140mm or bigger fan will likely blow the motherboard header.
Sorry but that doesn't make sense to me. Voltage controlling that 140mm fan last night pulled 0.3A total from the psu, and most of that is driving the lamptron. The fan only needs 0.13A at 12V. Given most headers are 1A these days it sounds like plenty of headroom to me.
Quote:
Originally Posted by
Corky34
:)
It's that they stop, well sort of, even when no stop is set in the BIOS. Between 25(ish)% and 35(ish)% PWM set in the BIOS they'll spin on first boot then a reboot, sleep or just falling bellow 1000rpm for to long and they'll stop spinning and go into a "I'm about to spin", "No I'm not", sort of jitter.
That behaviour is normal for low duty% pwm on most fans tbh. A common recommendation is to set BIOS to not use <40% pwm and it should stop that problem, but you won't get the fan speed lower than the threshold rpm that corresponds to. To do that you then need to add a voltage drop to the 12V feed to lower it instead and maintain the cycle at 40% (or possibly raise it depending on what you encounter).
Measure the pin voltages on the board. Is ground true 0V and is 12V actually supplying 12V? That is first thing I would be checking.
Which gigabyte x570 are you on? Master/Elite/Pro etc etc and which header are you using out of interest?
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
DanceswithUnix
That doesn't sound good :)
I'm glad you have said what the actual problem is though, it should make it somewhat easier to help. The thing is, 4 pin PWM headers are cheaper for the motherboard, so there isn't any reason to "fake" it. OFC that doesn't mean someone hasn't faked it for some bizarre reason, but it seems more likely to me that they simply messed up with their fan control and what you are looking at is just a bug in their control system.
Is it possible to set the BIOS to forced PWM rather than voltage control, and set a fixed fan speed which is fast enough to keep the CPU cool without being deafening? I'm not saying to use that as a long term solution, just wondering if avoiding all the fancy PID fan control logic and driving it old skool would give a stable fan speed.
If the OP can set min pwm% and just wants to reduce max rpm noise then they can use the bundled Noctua noise reducing cable, which SFAIK basically shoves a resistor in series to drop the voltage feed like I'm suggesting. Personally I want something hybrid that allows the user to both vary voltage and also set a PWM offset like their NF-FC1 controller, but where you can select a curve profile and combinations of the two across the range. Granted that is more complicated, but it is achievable. Whether enough people would buy it at whatever price it would end up being is another matter...
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Re: Budget multimeter recommendations?
[QUOTE=ik9000;4282599]
Quote:
Originally Posted by
ik9000
I've tested the mains with my VC99 (and a plug probe converter). Worked fine. I've tested numerous guitar+amp+pedal+psu electronics and it's been fine. It's not a fluke and I wouldn't use it in a lab/for military contracts etc but it is fine for the amateur hobbyist as a starting point.
The VC99/99+ has been pulled apart many times and it's cost-cutting design issues are well known. Probe sockets soldered directly on-top the PCB, untidy hand soldering, glass fuses instead of ceramic, insulation tape instead of physical distance, not a PTC or MOV to be seen. The meter does perform to spec out of the box. The trim pots aren't lacquered and it might not remain in spec for very long. It will work fine, until it doesn't. It is what it is, a 'cheap' Chinese OEM meter. You do as you please but sorry no, *I* am not poking something like that at 240V AC.
There are a lot of competing DMMs between a VC99 and even the least expensive Fluke. Uni-Trend don't compete with Fluke, any more than Draper competes with Snap-On. Uni-T meters do show up in all sorts of different scenarios and industries though, because the brand has been churning out 'inexpensive' budget instruments for 30 years. Even the contestants in the Pottery Throwdown were sporting Uni-T temperature meters on Sunday. They are like a red rash that spreads anywhere there is a need to take measurements electronically ;)
Quote:
I wouldn't push the OP to splash more money than they need to when they clearly are just putting their toe in the water so to speak.
If I could buy a much better designed and built product for a little extra cash, I would want to know about it. The VC99 is what, £35 delivered? The UT61D retails around £50 but £43 is common and if you look hard enough it's out there for £30 at the moment with free delivery.
The UT61D has probably seen more cash strapped EE students through college than any other meter in history. There are loads of tear-downs on Youtube if you want to compare the insides with the Vichy. No it is not a Fluke and no I wouldn't trust the 1KV safety rating and yes *I* would pay (significantly) more for some additional resolution. A first meter for a hobbyist, occasionally poking at 250VAC, I honestly can't think of a better value sub £50 meter.
Quote:
Noctua fans same tehnique spat out 2kHz so no idea what's going on there, and indeed whether the akasa fan was a fluke or whether the Noctua uses a different system
Noctua have very helpfully published their specs. According to Noctua, a 2KHz signal would equate to 60,000RPM(!) If you had the correct range selected, and didn't misread a decimal point, it's likely you measured noise - No trigger control remember. Another possibility is you shorted the 12V line while prodding about and entered 'broken' undefined territory.
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I agree with others' comments it's probably not the best way to try and measure fan behaviour, and hence I also use that Lamptron board I mentioned..
And you thought to pull me up on splashing cash? I take it you have the Lamptron for reasons other than measuring fan speed.
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Re: Budget multimeter recommendations?
Honestly its sometimes worth being patient on Ebay. The Brymens I got a couple of years ago,were about 20% of the RRP(clearance stock?). Uni-T,I assume is Uni-Trend?? I have seen them mentioned on EEVBlog before,so they must be decent enough for a hobbyist.
Quote:
Originally Posted by
ik9000
where are the fans in the case cat? Is one of them getting interference from another fan, say the cpu fan or similar that might be helping one keep going while the other struggles?
I need to investigate it further - will have to try another splitter and see. One is vertical exhaust and the other horizontal exhaust. But I just disconnected one,and it seemed OK,and then got distracted by other stuff! :D
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
matts-uk
The VC99/99+ has been pulled apart many times and it's cost-cutting design issues are well known. Probe sockets soldered directly on-top the PCB, untidy hand soldering, glass fuses instead of ceramic, insulation tape instead of physical distance, not a PTC or MOV to be seen. The meter does perform to spec out of the box. The trim pots aren't lacquered and it might not remain in spec for very long. It will work fine, until it doesn't. It is what it is, a 'cheap' Chinese OEM meter. You do as you please but sorry no, *I* am not poking something like that at 240V AC.
There are a lot of competing DMMs between a VC99 and even the least expensive Fluke. Uni-Trend don't compete with Fluke, any more than Draper competes with Snap-On. Uni-T meters do show up in all sorts of different scenarios and industries though, because the brand has been churning out 'inexpensive' budget instruments for 30 years. Even the contestants in the Pottery Throwdown were sporting Uni-T temperature meters on Sunday. They are like a red rash that spreads anywhere there is a need to take measurements electronically ;)
If I could buy a much better designed and built product for a little extra cash, I would want to know about it. The VC99 is what, £35 delivered? The UT61D retails around £50 but £43 is common and if you look hard enough it's out there for £30 at the moment with free delivery.
The UT61D has probably seen more cash strapped EE students through college than any other meter in history. There are loads of tear-downs on Youtube if you want to compare the insides with the Vichy. No it is not a Fluke and no I wouldn't trust the 1KV safety rating and yes *I* would pay (significantly) more for some additional resolution. A first meter for a hobbyist, occasionally poking at 250VAC, I honestly can't think of a better value sub £50 meter.
Noctua have very helpfully
published their specs. According to Noctua, a 2KHz signal would equate to 60,000RPM(!) If you had the correct range selected, and didn't misread a decimal point, it's likely you measured noise - No trigger control remember. Another possibility is you shorted the 12V line while prodding about and entered 'broken' undefined territory.
And you thought to pull me up on splashing cash? I take it you have the Lamptron for reasons other than measuring fan speed.
Wow, that comes across a little condescending. In reverse order:
I bought the Lamptron (RRP £60) for my own use and purposes. Can you show me where I suggested to the OP he get one? For £60 offering four LED control headers, thermal sensing and four PWM controllable independently of the BIOS and OS with an LED/LCD readout that's pretty good value IMO. But again, I haven't said the OP should get one, just that it's what I have available to read rpm on the fly on a test bench.
The OP is just wanting to tinker, and by their own comments, doesn't want to spend too much. I'm sure if you share a link to buy a better DMM at a similar price they will jump for it. (as might I for that matter if it's that much superior quality! I much prefer good kit to cheap kit for my own usage)
I will make a video of the Noctua fan tach feed into the DMM. There's no shorting going on and I was reading the screen correctly.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
DanceswithUnix
That doesn't sound good :)
I'm glad you have said what the actual problem is though, it should make it somewhat easier to help. The thing is, 4 pin PWM headers are cheaper for the motherboard, so there isn't any reason to "fake" it. OFC that doesn't mean someone hasn't faked it for some bizarre reason, but it seems more likely to me that they simply messed up with their fan control and what you are looking at is just a bug in their control system.
Is it possible to set the BIOS to forced PWM rather than voltage control, and set a fixed fan speed which is fast enough to keep the CPU cool without being deafening? I'm not saying to use that as a long term solution, just wondering if avoiding all the fancy PID fan control logic and driving it old skool would give a stable fan speed.
TBH i didn't say to much about the problem because it isn't exactly a problem, it's more an excuse to learn some stuff and scratch that "why's it doing that itch" (if that makes sense) and if i could fix it, plus like i said the lets touch it approach of testing if something's live can be painful. :)
Me saying faking it maybe using the wrong word but being an idiot when it comes to electronics i lack the knowledge to explain it better, i was going on the reply someone on reddit got from Noctua on the subject, as they say it's something exclusive to the NF-A12x25 PWM and Gigabyte boards but as they don't go into technically details i thought trying to workout the "why" would be a fun learning experience and good excuse to treat myself to a DMM.
It is possible to set the BIOS to forced PWM and I've tried that along with every combination i can think of, that's why it took me over a year to workout that it was a problem with new Noctua 120mm fans and PWM, you can probably imagine how long it takes to isolate something that only happens when using PWM, only when using a duty cycle bellow 35(ish)%, and only when using one of those fans. :) I've tried splitters, different fans, voltage and PWM control, and all combined with a cold boot followed by a restart. It was only last year that Noctua confirmed the problem was exclusive to their new 120mm fans on Gigabyte boards.
It's certainly possible to set a fixed PWM duty of 40(ish)% and it's not like it's loud at that speed, it's only spinning at around 1000rpm at that duty cycle after all, switching it to voltage control allows a slightly lower minimum speed of around 850rpm so it's defiantly not loud, but like i said it's more that itch of wanting to understand what's going on and an excuse to treat myself and hopefully learn something along the way. :)
Quote:
Originally Posted by
ik9000
That behaviour is normal for low duty% pwm on most fans tbh. A common recommendation is to set BIOS to not use <40% pwm and it should stop that problem, but you won't get the fan speed lower than the threshold rpm that corresponds to. To do that you then need to add a voltage drop to the 12V feed to lower it instead and maintain the cycle at 40% (or possibly raise it depending on what you encounter).
Measure the pin voltages on the board. Is ground true 0V and is 12V actually supplying 12V? That is first thing I would be checking.
Which gigabyte x570 are you on? Master/Elite/Pro etc etc and which header are you using out of interest?
Is it :confused:, in my old system it was all voltage control (manual control at that) so i was only going on what I've read and most of what I've read seems to suggest PWM should allow a lower rpm than voltage control but I'm seeing the opposite of that.
This is on the Pro but from what i gather it happens on all Gigabyte boards with the new Noctua 120mm fan (see above link to a reply someone got from Noctua).
I'm starting to feel guilty here as i never intended a thread about DMM recommendations into a troubleshoot a Nocuta PWM/Gigabyte fan thing, not that I'm not grateful for all your suggestions of what to try, it's just i don't want to waste everyone's valuable time and being a forum it's really difficult to convey thankfulness, gratitude, and reverence, it's not like i can shake your hands, smile, or sit wide eyed at having something explained so patiently to a luddite like me. :) :hexlub:
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
ik9000
Sorry but that doesn't make sense to me. Voltage controlling that 140mm fan last night pulled 0.3A total from the psu, and most of that is driving the lamptron. The fan only needs 0.13A at 12V. Given most headers are 1A these days it sounds like plenty of headroom to me.
I am being cautious there. Motors are easy to drive steady state, but the start up/stall currents can be pretty nasty.
PWM fans put the power control responsibility into the fan itself, which will know its own characteristics so should always be safe. On a motherboard, you are paying for some sort of voltage regulation into an unknown load which isn't nice to design when you are trying to keep costs down. ISTR my Antex 300 case came with a pair of fans that had their own fan control and plugged into a hard drive power connector because it was from a time when fans were all 3 pin, and they couldn't rely on motherboards to drive something like that.
OFC modern fans can have rather clever little brushless motors, so probably have nice soft start systems built in as well.
Quote:
Originally Posted by
ik9000
If the OP can set min pwm% and just wants to reduce max rpm noise then they can use the bundled Noctua noise reducing cable, which SFAIK basically shoves a resistor in series to drop the voltage feed like I'm suggesting. Personally I want something hybrid that allows the user to both vary voltage and also set a PWM offset like their NF-FC1 controller, but where you can select a curve profile and combinations of the two across the range. Granted that is more complicated, but it is achievable. Whether enough people would buy it at whatever price it would end up being is another matter...
As I said, I didn't expect the OP to run the system like that, just try it to make sure the fan is stable in the simplest of conditions.
Varying PWM and voltage feels rather inelegant. I guess it could work around poor pwm resolution, but one of the fundamental advantages of pwm is the high torque of full voltage. But then if I cared that much about fan control, then I'm sure I could knock something up using an Arduino that used dithered pwm to improve resolution over the usual 8 bit that hardware counters usually provide. Or something like the LED control I mentioned earlier, which operated more like a 1 bit audio DAC implemented in software.
An Arduino is an interesting thought for this thread. A bit of careful voltage buffering, one could probably work as a fan analyser.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
Corky34
TBH i didn't say to much about the problem because it isn't exactly a problem, it's more an excuse to learn some stuff and scratch that "why's it doing that itch" (if that makes sense) and if i could fix it, plus like i said the lets touch it approach of testing if something's live can be painful. :)
Me saying faking it maybe using the wrong word but being an idiot when it comes to electronics i lack the knowledge to explain it better, i was going on the reply
someone on reddit got from Noctua on the subject, as they say it's something exclusive to the NF-A12x25 PWM and Gigabyte boards but as they don't go into technically details i thought trying to workout the "why" would be a fun learning experience and good excuse to treat myself to a DMM.
<snip>
Is it :confused:, in my old system it was all voltage control (manual control at that) so i was only going on what I've read and most of what I've read seems to suggest PWM should allow a lower rpm than voltage control but I'm seeing the opposite of that.
This is on the Pro but from what i gather it happens on all Gigabyte boards with the new Noctua 120mm fan (see above link to a reply someone got from Noctua).
It sounds like Noctua's advice is as previous comment above - run the fan in Voltage regulation mode and ignore the PWM.
Quote:
Originally Posted by Noctua_FromRedditPost
This issue can be avoided by switching the fans to “Voltage or DC” mode in the UEFI BIOS. This way, the fans will be controlled via voltage regulation rather than PWM and the issue will no longer occur.
From their response it sounds like the issue is with Gigabyte's mobo circuitry rather than the fan itself so trying to measure the fan behaviour might not yield much in terms of finding a solution.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
ik9000
It sounds like Noctua's advice is as previous comment above - run the fan in Voltage regulation mode and ignore the PWM.
From their response it sounds like the issue is with Gigabyte's mobo circuitry rather than the fan itself so trying to measure the fan behaviour might not yield much in terms of finding a solution.
For sure and I'm not expecting I'll find a solution, as you know I'm not in the least bit knowledgable when it comes to the mystic arts of electronics and that's sort of why i feel guilty about taking up peoples time with talk of the problem as it probably can't be fixed, it's sort of inconsequential as the DMM and toy scope are the things that will allow me to scratch that itch of wanting to understand what the problem is, and come in handy for future projects of course.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
ik9000
Wow, that comes across a little condescending.
Sorry about that. I guess we all have our feelings.
Quote:
Originally Posted by ik9000
I wouldn't push the OP to splash more money than they need to...
How would you like me to feel about the above...
Quote:
Can you show me where I suggested to the OP he get one?
That's a rhetorical question and no.
As far as I am concerned you can buy what you want and use it as you will. I just found it ironic to be lectured on unnecessary cost while you name dropped an over-priced (IMO) designer fan controller to do a job a £2 MCU can do much better.
Quote:
The OP is just wanting to tinker, and by their own comments, doesn't want to spend too much.
What do you think I have been doing in my spare time since 1982? You have a designer fan controller to hand and I have about the same money in micros and components sat around my bench. I'm looking at schematics while you are scratching your head...
The OP needs to spend *enough*
Quote:
I'm sure if you share a link to buy a better DMM at a similar price they will jump for it.
Let me google that for you ;)
e-bay.co.uk. The price has been creeping up all week and the £30 deal lasted less than a day.
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(as might I for that matter if it's that much superior quality! I much prefer good kit to cheap kit for my own usage)
You very much get what you pay for with test equipment - Even the eye-watering brands like Fluke and Keysight justify their price. Yes you are paying for reputation but in a market where reputation is difficult to earn and very easy to lose.
Below Uni-T there is nothing I would buy. I have owned a couple of Vichy meters that came as free gifts, and were very quickly given away. Uni-T are a favourite with hobbyists and education for the reasons I said previously. A reputation for work-a-day quality with lots of features at budget prices. Just above Uni-T are the mid range brands like Brymen and B&K Precision.
Brymen are nothing special. Better build than Uni-T and they meet their Cat III (1KV) safety ratings. The main attraction are certain models punching well above their weight. My BM867s was silly cheap for a 500,000 count meter. B&K Precision are more expensive and more refined IMO. Brymen in my tool bag, B&K for the bench.
There are many others. I don't have enough direct experience of the other mid-price brands and meters to have an opinion on them.
Whichever meter you eventually buy, decide your priorities and budget, then plan to spend 50% more than you think ;)
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I will make a video of the Noctua fan tach feed into the DMM. There's no shorting going on and I was reading the screen correctly.
Those schematics... Short the 12 Volt line to the tacho or PWM lines even once, all bets are off. Not certainly broken but possibly broken. What we can say with absolute certainty is your fan is not spinning at 120,000RPM.
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Re: Budget multimeter recommendations?
I sense the Viennetta is going to start melting very soon! :P
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
ik9000
Those schematics... Short the 12 Volt line to the tacho or PWM lines even once, all bets are off. Not certainly broken but possibly broken.
I would hope not. I was told early on at university that anything I designed on the course would be expected that you can drop a spanner across any connections without fear of the consequences, or that design was a fail. IME that's a pretty normal mindset, only broken by the cheapest of illegal Chinese imports.
The "motherboard schematic" earlier was for PWM only header with no voltage control. In reality the 12V line will be under BIOS control to allow different DC voltages, which because it can't allow any noticeable voltage drop is going to have to be a small power FET, which means it will be the wrong way up to drive it from a logic output so will need a buffer transistor. Acting as a linear regulator would produce way too much heat, so if I was designing it I would PWM the 12V FET into a small reservoir capacitor so the power FET doesn't de-solder itself from thermal load. I would still want some protection on that to avoid customer returns if they ham fisted plug the wrong thing into a header, or backwards or something (we all have our moments, not judging customers) so I would put a polyfuse on there.
But the more I think about this, the more I think such things don't matter.
This is not a simple DC motor plugged into a 12V rail. It is a brushless motor taking inputs into its control system, plugged into a PWM header with its own control system and the two are interacting in a way that is unstable. That would make it a control theory problem (my least favourite subject at University) and might be tricky for a beginner to get to grips with.
So back to the OP wanting to learn stuff...
Things that light up or go round and round can be a very satisfying way to learn, so messing with fans could be a fun thing to do. It might be better to start with something like an Arduino, and try and drive a fan from that.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
CAT-THE-FIFTH
I sense the Viennetta is going to start melting very soon! :P
:rolleyes: and walk away. There is at least some useful guidance in there on multimeter quality.
FWIW I never said my fan was spinning at a gazillion rpm. I said the reading of 2kHZ from the Noctua made no sense, compared to the Akasa's reading using the same method which appeared to be correct.
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
ik9000
:rolleyes: and walk away. There is at least some useful guidance in there on multimeter quality.
I apparently have become the thing that I prophesized! :P
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
CAT-THE-FIFTH
I apparently have become the thing that I prophesized! :P
I think you mean prophesied! ;) And since a prophet is only proved correct when his prophesy is realised:
https://media1.tenor.com/images/fe8c...temid=18804692
:mrgreen:
edit: actually you mentioned melting. I can't find a vienetta melting, but this one if fun:
https://www.youtube.com/watch?v=Tbl7pXvH7fA
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Re: Budget multimeter recommendations?
Only polite to do an update, maybe someone will find it useful or have laugh at my expense. :)
I've ended up ordering a UNI-T UT61E from an EBay seller in China for £46.99 and I'll be getting the JYE-Tech DSO138mini toy scope from their official UK outlet when they get more stock in late Feb early March. I'm probably never going to use the full capabilities of the UT61E but seeing it was only £10 more than the VC99 that ik9000 recommended i thought I'd take a chance of not getting stung by a fake Chinese import or customs charges (i can't work out what the new rules are).
The recommendations from you guys made me revaluate Chinese brands instead of just discounting them all as junk (inaccurate or outright dangerous) and even though it is still five years out of date this series of YouTube videos helped.
I'm never going to test any high output stuff with it, it will be lucky if it even sees 240v once a decade. The toy scope should be good to practice on and hopefully I'll learn how to use a DMM along the way. :)
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Re: Budget multimeter recommendations?
I'm sure that multimeter will do you fine. I think mine is one I got from Maplin's one day when I needed one in a hurry. I don't like to spend too much, they get dropped down engine bays, onto garage floors etc. Or at least they do in my house :)
But that toy scope, it looks like they have the kit with the surface mount devices pre-soldered on in stock. Only the more expensive SMD kit is out of stock. You really want to solder those little gits?
I see the case is an extra £7.40 as well !
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Re: Budget multimeter recommendations?
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Originally Posted by
DanceswithUnix
But that toy scope, it looks like they have the kit with the surface mount devices pre-soldered on in stock. Only the more expensive SMD kit is out of stock. You really want to solder those little gits?
I see the case is an extra £7.40 as well !
If you mean on fluxworkshop they're different models, from what i read the original DSO138 got copied so much they stopped development on the firmware 4-5 years ago and made a new 'mini' version. I don't know if i want to solder SMD's as I've never done it before but it will be worth a laugh.
I'm not sure a case would be worth it, it may not even survive my ham fisted soldering. :D
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Re: Budget multimeter recommendations?
SMD components are tiny, the smaller ones are like a grain of sand, god help you if you drop one, you will never ever ever ever find it again :)
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Re: Budget multimeter recommendations?
Quote:
Originally Posted by
DanceswithUnix
I would hope not. I was told early on at university that anything I designed on the course would be expected that you can drop a spanner across any connections without fear of the consequences, or that design was a fail. IME that's a pretty normal mindset, only broken by the cheapest of illegal Chinese imports.
I was merely a jobbing wireman promoted to test engineer. Nobody I worked for designed PCBs to be safe when powered up with the case removed.
Poking at a PC fan header with multi-meter probes while the board is live presents an obvious risk of shorting the tacho on Pin3 to the 12V supply on the adjacent Pin2. In the document I posted earlier Noctua are very clear that shorting the 12V line to the tacho or PWM line can break the fan circuit instantly. ITE super i/o data-sheets are not so clear but the logic pin current limits and "not 5V tolerant" warnings suggest a 12V short may end badly. Generally speaking I wouldn't trust a 3.3V logic pin to survive connection to a 12V supply rail.
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The "motherboard schematic" earlier was for PWM only header with no voltage control.
The fan header is backwards compatible and suitable for brushed and brushless DC fans with fixed, thermostatic relay, voltage regulated, PWM and MCU speed control. The schematic contains nothing that would prevent one technology working with any other. You can't really call it a standard but everyone follows Intel.
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But the more I think about this, the more I think such things don't matter.
You're right, it doesn't matter. Either side of the interface manufacturers can implement as they like provided voltage, current and timing parameters remain compatible at the header. The common header and pin out allows PC fans and motherboards to be widely mixed and matched.
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This is not a simple DC motor plugged into a 12V rail. It is a brushless motor taking inputs into its control system, plugged into a PWM header with its own control system and the two are interacting in a way that is unstable.
You are so over-thinking it. Brushless PC fans have a BLDC control chip on the fan head. Apart from needing a correctly polarised supply, brushless fans with a BLDC chip behave remarkably similar to the brushed fans they replace.
There is no need to guess how it might work. Manufacturers have documented just about every fan control arrangement known to man. https://www.nxp.com/docs/en/white-paper/QD4DCFAN.pdf
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I would still want some protection on that to avoid customer returns if they ham fisted plug the wrong thing into a header, or backwards or something (we all have our moments, not judging customers)
You have to be pretty ham fisted to force a Molex-KK on backwards. We did have a gamer bring a PC in with the connector wired backwards, after his mate thought it would reverse the direction of the fan. The tacho was toast.
