Excellent video! It boggles my mind that the view count is so low, but then again, maybe not... I admit I don't know where the ability to measure an AC/DC reading would come in handy in electrical work. Can you talk about the practical application at some point? Thanks!
Excellent video, I was wondering if a meter like a Fluke 87 will read the correct DC value when measuring a complex waveform with a fairly large AC component? Say 9V DC and 2V AC? I had never needed to take such a reading and expected the TRMS Fluke 87 to give me AC+DC but it didn't and your video explained it very clearly.
In DC mode it will show you the correct DC value (the math average). In AC mode, the Fluke 87 is "AC Coupled", meaning that it filters out the DC offset and gives you the TRMS of just the remaining AC signal.
Very clear explanation Sir thankyou. Appreciate it... I'm in the market for a TRMS or better yet AC+DC TRMS multi meter but with multitude of other functions like Lux, temperature, humidity, sound etc like the Centech P98674 or Mastech MS8229 (both being the same are non TRMS). Can you recommend any? Thankyou.
Thanks for the excellent video.Please explain the effect of measuring square wave , pulse width modulation(PWM) signal and smps / dc-dc converter switching mosfet signal with multi-meter dc mode and true RMS mode.Are these type of signals can be called AC signals?
On the rectified signal. While without a capacitor the ripple is excessive. It is still dc though right ? Its all above ground (so to speak). Why does it measure an AC ? Its more of a pulsed dc. Its all in the same direction. ?
That is an excellent question. You are correct rectified sine is a DC signal because the polarity of the waveform never changes (in this case is always positive).
The true RMS reading at 5:31 of 5.288 is interesting. How did it arrive at this? To get an AC reading out of a pure DC signal it must assume that the waveform is symmetrical about the zero volt axis. I.e., I assumed that it must subtract off one half the peak voltage from the rectified sine wave, square that, integrate it over half a period and take the resulting square root. That would give a voltage of V(t) = Vp*sin(wt) - Vp/2. Using this (and assuming Vp = 17 V which is what he is using) I get an RMS voltage of 5.72 volts. So not sure how it's calculating this.
Hmmm... Very nice demonstration....When you add in the rectifier, the output is always positive and the current does not change direction so it is not AC but DC with a large ripple which can be reduced with a capacitor?????
Would the fluke 117 be an ac+dc? I've had several different readings in its auto low impedance mode that have thrown me for a loop. Great video! i always appreciate your knowledge.
No, the 117 is not AC+DC. The low impedance could have been affecting your readings, as you are basically putting a 3K ohm resister in your circuit, when you use Lo Z.
Lo Z is used in cases where you want to eliminate what's called ghost voltage (parasitic voltage) in Ac measurements by introducing a 3K load in parallel with the measurement. The high-end handheld Fluke 289 and 287 can do AC+DC. Thanks.
zummerzet woodsman All the time. As shown in the video, it is very common to have AC signals with a DC offset. Or, having DC power supplies with a large amount of AC ripple on them.
@@MultiMeterChannel ok .so as a bigginer could point me to a video that would explain ac/DC on the same line. I bought a second hand fluke 189 meter on the rotary display it mentions ac/dc .I have tried to Googled it to no avail
zummerzet woodsman Your Fluke 189 is capable of displaying AC+DC. When you go to that dial setting, you can hit the select button, and it will show BOTH the AC and DC values at the same time. One will be bigger in the screen, and one smaller. Hitting the select again, will reverse the AC and DC readings (switch which is larger or smaller). Hitting again, will display the AC+DC together as one number. Just go to the Fluke website, and download the 189 user manual. No need to google it, your answer is in there........
sir , im an electricity engineer and im really say the things i learn from your videos than never told us in university . thanks
Excellente video. Recently I need to measure DC + AC RMS, when I found this video.
i had the biggest "O!" moment watching your video. Great explonation and i love the visual tools used.
Excellent video! It boggles my mind that the view count is so low, but then again, maybe not... I admit I don't know where the ability to measure an AC/DC reading would come in handy in electrical work. Can you talk about the practical application at some point? Thanks!
Excellent video, I was wondering if a meter like a Fluke 87 will read the correct DC value when measuring a complex waveform with a fairly large AC component? Say 9V DC and 2V AC? I had never needed to take such a reading and expected the TRMS Fluke 87 to give me AC+DC but it didn't and your video explained it very clearly.
In DC mode it will show you the correct DC value (the math average).
In AC mode, the Fluke 87 is "AC Coupled", meaning that it filters out the DC offset and gives you the TRMS of just the remaining AC signal.
I'm happy With that information, thanks, I'm appreciate
Very clear explanation Sir thankyou. Appreciate it... I'm in the market for a TRMS or better yet AC+DC TRMS multi meter but with multitude of other functions like Lux, temperature, humidity, sound etc like the Centech P98674 or Mastech MS8229 (both being the same are non TRMS). Can you recommend any? Thankyou.
Thanks for demystifying :)
Thank you so much for this information!
Very good explanation
..... Mate, if it was up to me, I would commission a bronze statue of you in the town square.
(holding a true RMS DMM) Well done.
👍👍
Very nice!
Thanks.
Nice Video Bro.
Thanks for the excellent video.Please explain the effect of measuring square wave , pulse width modulation(PWM) signal and smps / dc-dc converter switching mosfet signal with multi-meter dc mode and true RMS mode.Are these type of signals can be called AC signals?
Thank you!
On the rectified signal. While without a capacitor the ripple is excessive. It is still dc though right ? Its all above ground (so to speak). Why does it measure an AC ? Its more of a pulsed dc. Its all in the same direction. ?
That is an excellent question. You are correct rectified sine is a DC signal because the polarity of the waveform never changes (in this case is always positive).
The true RMS reading at 5:31 of 5.288 is interesting. How did it arrive at this? To get an AC reading out of a pure DC signal it must assume that the waveform is symmetrical about the zero volt axis. I.e., I assumed that it must subtract off one half the peak voltage from the rectified sine wave, square that, integrate it over half a period and take the resulting square root. That would give a voltage of
V(t) = Vp*sin(wt) - Vp/2. Using this (and assuming Vp = 17 V which is what he is using) I get an RMS voltage of 5.72 volts. So not sure how it's calculating this.
Hi, is there some things one can do with an analog meter that you can't do with a digital multimeter?
I am curious how the uni-t waveform generator has worked for you? Is it a good device for professional work? Thank you very much.
Hmmm... Very nice demonstration....When you add in the rectifier, the output is always positive and the current does not change direction so it is not AC but DC with a large ripple which can be reduced with a capacitor?????
vs68s
Correct.
🖤
Would the fluke 117 be an ac+dc? I've had several different readings in its auto low impedance mode that have thrown me for a loop. Great video! i always appreciate your knowledge.
No, the 117 is not AC+DC. The low impedance could have been affecting your readings, as you are basically putting a 3K ohm resister in your circuit, when you use Lo Z.
Lo Z is used in cases where you want to eliminate what's called ghost voltage (parasitic voltage) in Ac measurements by introducing a 3K load in parallel with the measurement.
The high-end handheld Fluke 289 and 287 can do AC+DC.
Thanks.
My frent, if get a lamp on this 3 methods you can see the same results. So the true rms meter is the fluke and the other 2 is only for festivals
rms clamp meter affect the DC amp reading please tell
zeeshan ch
RMS is only for AC, not DC.
When would you have ac/DC running together
zummerzet woodsman
All the time. As shown in the video, it is very common to have AC signals with a DC offset. Or, having DC power supplies with a large amount of AC ripple on them.
@@MultiMeterChannel ok .so as a bigginer could point me to a video that would explain ac/DC on the same line. I bought a second hand fluke 189 meter on the rotary display it mentions ac/dc .I have tried to Googled it to no avail
zummerzet woodsman
Your Fluke 189 is capable of displaying AC+DC. When you go to that dial setting, you can hit the select button, and it will show BOTH the AC and DC values at the same time. One will be bigger in the screen, and one smaller. Hitting the select again, will reverse the AC and DC readings (switch which is larger or smaller). Hitting again, will display the AC+DC together as one number.
Just go to the Fluke website, and download the 189 user manual. No need to google it, your answer is in there........
First to say First