Budget multimeter recommendations?

[CAT-THE-FIFTH]

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.

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!

[ik9000]

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.

[Corky34]

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.

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 , 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.

[DanceswithUnix]

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.

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.

[ik9000]

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 , 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.

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.

[Corky34]

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.

[matts-uk]

Wow, that comes across a little condescending.

Sorry about that. I guess we all have our feelings.

I wouldn't push the OP to splash more money than they need to...

How would you like me to feel about the above...

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.

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*

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.

(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

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.

[CAT-THE-FIFTH]

I sense the Viennetta is going to start melting very soon!

[DanceswithUnix]

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.

[ik9000]

I sense the Viennetta is going to start melting very soon!

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.

[CAT-THE-FIFTH]

and walk away. There is at least some useful guidance in there on multimeter quality.

I apparently have become the thing that I prophesized!

[ik9000]

I apparently have become the thing that I prophesized!

I think you mean prophesied! And since a prophet is only proved correct when his prophesy is realised:





edit: actually you mentioned melting. I can't find a vienetta melting, but this one if fun:

[Corky34]

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.

[DanceswithUnix]

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 !

[Corky34]

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.

[Jonj1611]

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