Thank you very much for this video. I am studying power electronics and electronics at the University and I felt curiosity for how these instruments might work. It was clear to me that I was measuring volts, amps, ohms, etc; but I was intrigued and asked myself ever since, how do they do the math? what does the instrument interpret and show us? and why is that the professor constantly affirms that whenever using the multimeter on AC, it was giving me a rms value? This video has cleared many of my doubts and I find it really useful, and it hooked me until the very ending of it. Thank you for your contribution, it means a lot to me and to a lot of people that go a little bit far beyond when learning and I can say that I learned from you something I consider to be very important to me, even though the professor won't grade the students accordingly to what people truly know or learn. Again thank you very much, I hope your video reaches many more people as well!
Well I'm trying to learn how to use this Kobalt RMS Digital Multimeter that I bought at Lowes. I bought it to test an oven element, or the terminal thing in the back that can also be replaced. I have a stove and oven built into the counter top. I have learned there are four screws to remove the actual oven from the cabinet. The video I watched made it seem possible that if I have a meter I might be able to actually get some cheap and easy knowledge about the oven part of the stove, because everything works but the oven but we had lightning hit a tree in the back yard many years ago and at the time it knocked out a bunch of our electronics. Now as the sole homeowner I'm trying to do more things for myself. My brother who died in 2020 could do just about everything. Me, I do basic stuff. Anyway, it must be nice to listen to stuff like this and leave such a video with enhanced knowledge. Me, I just want to know what the heck I am doing. My meter has settings that make it look like a clock. I can't find a video of anyone using a meter like this. I got a plug in meter, a pen meter and this RMS all for about $35. I sure wish I knew how to use it though without getting a degree in electronics and so on.
I’ve watched a ton of your videos, great content. Are you still out there? It would be really cool if you gave us a short clip on how you are doing and your intentions for the channel. I would love to see more videos as I find your way of explaining things easy to follow.
Great explanation of the RMS verses non RMS. It's been a long time understanding this, but this is a great refresher. Back in the day audio amplifiers of dubious marketing would use Peak, Instantaneous Peak to Peak and may have mentioned RMS power ratings. Then there is is the dodgy subject harmonic distortion. I have heard this harmonic distortion on the A.C. line is some cause for concern. Causes can be from switch mode power supplies found in lighting devices and power supplies from "wall warts" to computers to motor controls.
Craig Nehring Harmonic distortion is definitely a concern and can cause problems with various devices in addition to costing the utility companies money and other communication interference issues. To measure harmonic distortion accurately you would need a Harmonic Power Analyzer which is a more expensive and more specialized piece of kit.
Honestly although some devices do require a near sinusoidal input, speakers really are designed to take whatever you throw at them. I'm not sure why amp clipping has become such a cuss word. Because there are many audio production applications that you can use clipping for. And as long as your peak voltage doesn't do over and neither does your RMS, there's really no reason to be so concerned about it
In an amplifier, if it runs out of power into say a 3 way crossover, the tweeter is going to "see" more or less a D.C. supply wave form (severely clipped) and burn out the tweeter. Power in today's MOSFET amps is huge, not the case when 40 Watts RMS was considered a lot of power. Yet any amp can go into clipping for various reasons. Clipping on an input is one thing, on the output it can cause over heating of the voice coils that have AC resistance wave form ratings. I have in my youth burned out more than one tweeter driving speakers this way, the odd thing was at the time I really could not hear it happening.
Craig Nehring Yes I'll agree that clipping an output is definitely a problem, but a square wave is just a sum of many sine waves, as is any kind of distortion If you clip an input, and then filter that clipped wave into the operating range of the tweeter tough, and at that point are not exceeding the rated wattages, would you agree that it shouldn't be a problem
These are good videos, you should include chop and what actually happens in these circuits. Also include losses for saturation in those magnetic fields. I know it would be difficult, but it would explain better the difference between pure sine wave and modified sine wave and the losses associated with the implementation of those products on either platform.
I've found that the chepo Harbour Freight meters are great for boats, which are usually all DC. I rarely measure AC because I mostly use them for hobbish things. However, I do have an RMS meter sitting around. Anyway, good video.
I love your craftsman the most because of the scope on it. I think next free cash I got which isn't going into my RV will be to try to find that one on ebay soon as i see one, or else where. lol. all i got at the moment is a precision gold WG020. Really trying to just search for the model number for that craftsman you're about the only person that comes up really anymore with info about that meter.
Thank you! I am a dunce when it comes to electricity but you are so clear and precise that even I understand. You are an excellent technical instructor. One question, assuming that it is a true RMS multimeter, is there any significant advantage in terms of practical use in getting a very expensive one like a Fluke or getting a more moderate priced one of reasonable quality?
Charles Stokes I don't own a Fluke because they are expensive new and overpriced used. (Just buy new in my opinion) That said they are very nice meters which have quick response and hold up well under heavy use. For example: Even simple tasks like measuring continuity or measuring a resistor take an extra little bit of time with inexpensive meters because it usually takes some time for them to 'settle out' on the correct reading. Flukes and other higher end ones are nearly instant saving you time. For commercial applications I would always choose a nice one like a Fluke however if you're only using it occasionally then I don't see the need to spend an extra $100. Multimeter technology isn't very high tech so even the cheap-o ones do it pretty well. Or if you want - treat yourself to a nice Fluke. And it will hold its value over time.
I have a fluke and TRMS mastech and also two mastech non TRMS models. The thing is in the electronics I work with I almost never measure ac voltage/current. In fact I cannot think of a circumstance when I would. So I would not say non TRMS meters are useless when this feature is only needed in 1% of situations (still cannot think of one). Any signals I look at I use a DSO. A multimeter is useless when compared with a DSO. So if it is DC any meter will do. If it is not DC use a digital storage scope.
Just discovered that my clamp meter (Mastech MS2108A) isn't RMS, but the MS2108 is (notice the missing 'A' in the model). I bought it after seeing you using the same model but I don't know if yours is the RMS model or not. Not a big deal for me as I don't deal with AC but would have been nice if it was just for those one off's.
Going back a couple of years - You rebuilt an APC back up UPS 600. Happens that the circuit board (layout anyway) is exactly the same as an APC SC450 that I have. I'd like to adjust the max current flow slightly upward (before alarm/shutdown) as I'm only using it for surge protection and to keep the DVR online during infrequent power failures for a few seconds. The TV and DVR together are ~ 300 watts (max on unit is 280). You put a "wire" across the current transformer to do this. What would you recommend that I do in this case? Thanks in advance for your time.
excellent video!!!. the average of a pure pure sine wave is not 0? (12:12) I have a chinese copy of that kill a watt but not shure if it is true rms. I will have to try that with my fluke. Thansk!!! saludos
I like all your videos I have a small bank of 10 batteries. I'm ready for when the power goes out. I want to know your opinion on a samlex 350 watt sws pure sine inverter. thanks for all you a taught me. Keep new videos coming
Hi ive not long gone off grid had a surprise when plugged inverter to battery bank then plugged in soldering iron then went to solder wire to battery banks positive check it out it sparks a good one can you explain why ta
hi we have a 38'5th wheel, do you think a 6000 pure sine wave inverter will power all?, 8 battery pack, solar panel, do you sell inverters?thank you vince
Is it cheaper to make a multimeter that computes average AC voltage? If it's just a matter of slightly more complex circuitry, then do you think all multimeters will eventually be RMS?
Lorraine Hillman In nearly every case if it doesn't specifically state it then it isn't. I'm trying to think of an easy way to tell experimentally without any special equipment but I'm running a blank at the moment...
Wow! Where'd you find that old gem! I had batteries leak in it rather catastrophically a while back and was worried, but it survived without damage to the circuit boards. It's still my favorite DMM.
@@knurlgnar24I found it on Facebook marketplace. The guy didn't want to ship it at first. I was looking for another craftsman meter that I have that broke but came across this one. It looked nice & seems like it has everything with it hopefully it works. I paid 50 for it total. Is there anything I should know about it? Maybe you can make a video on how to use it when you get a chance.
@@knurlgnar24 i just received the meter the other day it's in good condition only thing when testing capacitors the reading seems to be off a 2.2uf is reading 1.5 not sure if there's a way to adjust it or not.
I don't really know if it would be possible to have a "fake" RMS.. You could run it through some sort of digital processing but you'll end up with basically the same result. For example. In music production you use rms metering (since it's done by a computer, it's digital calculation) and it's precise enough that you can do a mix based on RMS levels instead of peak.
sum it up, - both rms and non is not fully adequate.. you really need higher cost gear of you really wanne get insigt an measure ac etc..anyway, so just do what most people do, and pick the pretty DMM..I have been looking for this model, but seems to be oout of production, and a shame ' looks awesome.. s-media-cache-ak0.pinimg.com/236x/54/9f/b9/549fb9d0c14584c406503ad270c65e77.jpg
Well I mean RMS is by definition how you calculate DC from AC. So it's good for power applications. As for audio, yeah you basically have to go by ear. dB perception is very complicated
AC rms voltage mnt types: temp, peakx0.707, avgx1.11, analog, & digital sampling Average and Root Mean Square (RMS) Calculations th-cam.com/video/TDgTYsgz4UI/w-d-xo.html
Thank you very much for this video. I am studying power electronics and electronics at the University and I felt curiosity for how these instruments might work. It was clear to me that I was measuring volts, amps, ohms, etc; but I was intrigued and asked myself ever since, how do they do the math? what does the instrument interpret and show us? and why is that the professor constantly affirms that whenever using the multimeter on AC, it was giving me a rms value? This video has cleared many of my doubts and I find it really useful, and it hooked me until the very ending of it. Thank you for your contribution, it means a lot to me and to a lot of people that go a little bit far beyond when learning and I can say that I learned from you something I consider to be very important to me, even though the professor won't grade the students accordingly to what people truly know or learn. Again thank you very much, I hope your video reaches many more people as well!
Well I'm trying to learn how to use this Kobalt RMS Digital Multimeter that I bought at Lowes. I bought it to test an oven element, or the terminal thing in the back that can also be replaced. I have a stove and oven built into the counter top. I have learned there are four screws to remove the actual oven from the cabinet. The video I watched made it seem possible that if I have a meter I might be able to actually get some cheap and easy knowledge about the oven part of the stove, because everything works but the oven but we had lightning hit a tree in the back yard many years ago and at the time it knocked out a bunch of our electronics. Now as the sole homeowner I'm trying to do more things for myself. My brother who died in 2020 could do just about everything. Me, I do basic stuff. Anyway, it must be nice to listen to stuff like this and leave such a video with enhanced knowledge. Me, I just want to know what the heck I am doing. My meter has settings that make it look like a clock. I can't find a video of anyone using a meter like this. I got a plug in meter, a pen meter and this RMS all for about $35. I sure wish I knew how to use it though without getting a degree in electronics and so on.
I’ve watched a ton of your videos, great content. Are you still out there? It would be really cool if you gave us a short clip on how you are doing and your intentions for the channel. I would love to see more videos as I find your way of explaining things easy to follow.
thanks for the valuable information and very very detailed (yet simple to understand) explanation
Great explanation of the RMS verses non RMS.
It's been a long time understanding this, but this is a great refresher.
Back in the day audio amplifiers of dubious marketing would use Peak, Instantaneous Peak to Peak and may have mentioned RMS power ratings. Then there is is the dodgy subject harmonic distortion. I have heard this harmonic distortion on the A.C. line is some cause for concern. Causes can be from switch mode power supplies found in lighting devices and power supplies from "wall warts" to computers to motor controls.
Craig Nehring Harmonic distortion is definitely a concern and can cause problems with various devices in addition to costing the utility companies money and other communication interference issues. To measure harmonic distortion accurately you would need a Harmonic Power Analyzer which is a more expensive and more specialized piece of kit.
Honestly although some devices do require a near sinusoidal input, speakers really are designed to take whatever you throw at them.
I'm not sure why amp clipping has become such a cuss word. Because there are many audio production applications that you can use clipping for. And as long as your peak voltage doesn't do over and neither does your RMS, there's really no reason to be so concerned about it
In an amplifier, if it runs out of power into say a 3 way crossover, the tweeter is going to "see" more or less a D.C. supply wave form (severely clipped) and burn out the tweeter. Power in today's MOSFET amps is huge, not the case when 40 Watts RMS was considered a lot of power. Yet any amp can go into clipping for various reasons. Clipping on an input is one thing, on the output it can cause over heating of the voice coils that have AC resistance wave form ratings.
I have in my youth burned out more than one tweeter driving speakers this way, the odd thing was at the time I really could not hear it happening.
Craig Nehring Yes I'll agree that clipping an output is definitely a problem, but a square wave is just a sum of many sine waves, as is any kind of distortion
If you clip an input, and then filter that clipped wave into the operating range of the tweeter tough, and at that point are not exceeding the rated wattages, would you agree that it shouldn't be a problem
Yep, there is no problem then as it is just a sound effect at that point and will come out sinusoidal.
These are good videos, you should include chop and what actually happens in these circuits. Also include losses for saturation in those magnetic fields. I know it would be difficult, but it would explain better the difference between pure sine wave and modified sine wave and the losses associated with the implementation of those products on either platform.
I've found that the chepo Harbour Freight meters are great for boats, which are usually all DC. I rarely measure AC because I mostly use them for hobbish things. However, I do have an RMS meter sitting around. Anyway, good video.
I love your craftsman the most because of the scope on it. I think next free cash I got which isn't going into my RV will be to try to find that one on ebay soon as i see one, or else where. lol. all i got at the moment is a precision gold WG020. Really trying to just search for the model number for that craftsman you're about the only person that comes up really anymore with info about that meter.
Kil-A-Watt P3 sounds like a great fill in the gap option.
Thank you! I am a dunce when it comes to electricity but you are so clear and precise that even I understand. You are an excellent technical instructor.
One question, assuming that it is a true RMS multimeter, is there any significant advantage in terms of practical use in getting a very expensive one like a Fluke or getting a more moderate priced one of reasonable quality?
Charles Stokes I don't own a Fluke because they are expensive new and overpriced used. (Just buy new in my opinion) That said they are very nice meters which have quick response and hold up well under heavy use. For example: Even simple tasks like measuring continuity or measuring a resistor take an extra little bit of time with inexpensive meters because it usually takes some time for them to 'settle out' on the correct reading. Flukes and other higher end ones are nearly instant saving you time. For commercial applications I would always choose a nice one like a Fluke however if you're only using it occasionally then I don't see the need to spend an extra $100. Multimeter technology isn't very high tech so even the cheap-o ones do it pretty well. Or if you want - treat yourself to a nice Fluke. And it will hold its value over time.
I have a fluke and TRMS mastech and also two mastech non TRMS models. The thing is in the electronics I work with I almost never measure ac voltage/current. In fact I cannot think of a circumstance when I would.
So I would not say non TRMS meters are useless when this feature is only needed in 1% of situations (still cannot think of one). Any signals I look at I use a DSO. A multimeter is useless when compared with a DSO.
So if it is DC any meter will do. If it is not DC use a digital storage scope.
I'm very surprised you haven't done any videos on a solar system considering I saw solar panels in your garage in a past video. Any plans?
Just discovered that my clamp meter (Mastech MS2108A) isn't RMS, but the MS2108 is (notice the missing 'A' in the model). I bought it after seeing you using the same model but I don't know if yours is the RMS model or not. Not a big deal for me as I don't deal with AC but would have been nice if it was just for those one off's.
Going back a couple of years - You rebuilt an APC back up UPS 600. Happens that the circuit board (layout anyway) is exactly the same as an APC SC450 that I have. I'd like to adjust the max current flow slightly upward (before alarm/shutdown) as I'm only using it for surge protection and to keep the DVR online during infrequent power failures for a few seconds. The TV and DVR together are ~ 300 watts (max on unit is 280). You put a "wire" across the current transformer to do this. What would you recommend that I do in this case? Thanks in advance for your time.
excellent video!!!.
the average of a pure pure sine wave is not 0? (12:12)
I have a chinese copy of that kill a watt but not shure if it is true rms. I will have to try that with my fluke. Thansk!!!
saludos
current/volt in this instance is used to measure the power(energy spent per unit time) and hence it is considered scalar(direction doesn't matter)
I like all your videos I have a small bank of 10 batteries. I'm ready for when the power goes out. I want to know your opinion on a samlex 350 watt sws pure sine inverter. thanks for all you a taught me. Keep new videos coming
Hi ive not long gone off grid had a surprise when plugged inverter to battery bank then plugged in soldering iron then went to solder wire to battery banks positive check it out it sparks a good one can you explain why ta
hi we have a 38'5th wheel, do you think a 6000 pure sine wave inverter will power all?, 8 battery pack, solar panel, do you sell inverters?thank you vince
Hey knurlgnar where is your video on solar or just led lighting in general? Your video shootouts are muchly Moe butter than amazon reviews.
Is it cheaper to make a multimeter that computes average AC voltage? If it's just a matter of slightly more complex circuitry, then do you think all multimeters will eventually be RMS?
Yes
What about old skool VTVM meters RMS or No? I guess I could google it easy enough.
Do you nead the DVA peak volt adapter in a true rms multimeter?
6:45 i have this Red Multimeter and i like it.
When i was buying my first meter i was long at them thinking to myself.. why make one that's not true rms?
Knurlgnar, sir your vids are not showing up in my e-mail notifications. Is anyone else having this issue?
Um, why multiply by a factor of 2/sqrt(2), instead of just dividing by sqrt(2)?
Theartlav or why not multiply by a factor of sqrt(2)/2? You nitpick over this and yet make an error in your criticism framed as a question.
How do you tell if a meter is RMS or not? My meters dons say.
Lorraine Hillman In nearly every case if it doesn't specifically state it then it isn't.
I'm trying to think of an easy way to tell experimentally without any special equipment but I'm running a blank at the moment...
Type in the brand and model number on the internet. it will probably have some information about your meter
i just ordered the craftsman meter
Wow! Where'd you find that old gem! I had batteries leak in it rather catastrophically a while back and was worried, but it survived without damage to the circuit boards. It's still my favorite DMM.
@@knurlgnar24I found it on Facebook marketplace. The guy didn't want to ship it at first.
I was looking for another craftsman meter that I have that broke but came across this one. It looked nice & seems like it has everything with it hopefully it works. I paid 50 for it total. Is there anything I should know about it?
Maybe you can make a video on how to use it when you get a chance.
@@knurlgnar24 i just received the meter the other day it's in good condition
only thing when testing capacitors the reading seems to be off a 2.2uf is reading 1.5 not sure if there's a way to adjust it or not.
Peak to Peak times .707 divided by 2 on a non true RMS meter will give the same results as a true RMS meter..
Only with a pure sine wave signal. This would be the point of the entire video.
ELI5 please.
Shouldn't "True RMS" be the standard, then?
I don't really know if it would be possible to have a "fake" RMS.. You could run it through some sort of digital processing but you'll end up with basically the same result.
For example. In music production you use rms metering (since it's done by a computer, it's digital calculation) and it's precise enough that you can do a mix based on RMS levels instead of peak.
Hi, could you send me a schematic for a pure sine inverter.
sum it up, - both rms and non is not fully adequate.. you really need higher cost gear of you really wanne get insigt an measure ac etc..anyway, so just do what most people do, and pick the pretty DMM..I have been looking for this model, but seems to be oout of production, and a shame ' looks awesome..
s-media-cache-ak0.pinimg.com/236x/54/9f/b9/549fb9d0c14584c406503ad270c65e77.jpg
Well I mean RMS is by definition how you calculate DC from AC. So it's good for power applications.
As for audio, yeah you basically have to go by ear. dB perception is very complicated
If you have the money Fluke hands down every time
mattmopar440 Fluke is the de facto Gold Standard.
***** Brymen will be the Sliver standard. haha. Fluke 115 / 117 is good enough for daily usage.
I havent heard from you in a while. Can you tell me the best meter for battery reading? Check my channel if you get board. Cheers
AC rms voltage mnt types: temp, peakx0.707, avgx1.11, analog, & digital sampling
Average and Root Mean Square (RMS) Calculations th-cam.com/video/TDgTYsgz4UI/w-d-xo.html
Charge your pen
silly hand stuff................