| Pages:
1
..
101
102
103 |
mr_bovinejony
Hazard to Others
Posts: 121
Registered: 20-4-2018
Member Is Offline
Mood: ASS
|
|
Nope but I do love that book lol. Theres another shortter one called the recent advances in phosgene chemistry, these are the only two books I have on
phosgene
|
|
|
mr_bovinejony
Hazard to Others
Posts: 121
Registered: 20-4-2018
Member Is Offline
Mood: ASS
|
|
Nope but I do love that book lol. Theres another shortter one called the recent advances in phosgene chemistry, these are the only two books I have on
phosgene
|
|
|
bnull
Hazard to Others
Posts: 138
Registered: 15-1-2024
Location: Between the Atlantic and the Pacific Ocean
Member Is Online
Mood: Feeling like a pinky-bending bluesman.
|
|
What about "A mild and efficient method for the preparation of acyl azides from carboxylic acids using triphosgene" (Tetrahedron Letters 43 (2002)
1345–1346)? Edit: No, it isn't.
Do you remember what was the reaction?
[Edited on 19-3-2024 by bnull]
Quod scripsi, scripsi.
B. N. Ull
|
|
|
yobbo II
National Hazard
Posts: 709
Registered: 28-3-2016
Member Is Offline
Mood: No Mood
|
|
Could someone tell me what is meant by the feature on these true RMS meters?
AC + DC Measurement
The meters are at this link>
https://www.aliexpress.com/item/1005003126913969.html?src=go...
It is circled on the picture
TIA,
Yob
[Edited on 27-3-2024 by yobbo II]
|
|
|
B(a)P
International Hazard
Posts: 1114
Registered: 29-9-2019
Member Is Offline
Mood: Festive
|
|
eevblog is a great resource for electronics questions. Check out this thread.
|
|
|
bnull
Hazard to Others
Posts: 138
Registered: 15-1-2024
Location: Between the Atlantic and the Pacific Ocean
Member Is Online
Mood: Feeling like a pinky-bending bluesman.
|
|
When the voltage has a component AC and a component DC (DC offset), ordinary meters measure either the AC component or the DC component but not both
at the same time. The AC+DC meter measures both and outputs this:
$$V_{RMS_{(AC+DC)}}=\sqrt{V_{DC}^2+V_{RMS_{AC}}^2}.$$
It's for those times when you want to know the power dissipation in a resistor, for example.
Edit: Victim of ninja attack because of a typo in LaTeX. You won't get me next time, B(a)P, mark my words. 
[Edited on 27-3-2024 by bnull]
Quod scripsi, scripsi.
B. N. Ull
|
|
|
yobbo II
National Hazard
Posts: 709
Registered: 28-3-2016
Member Is Offline
Mood: No Mood
|
|
Thanks you folks.
Yob
|
|
|
wg48temp9
National Hazard
Posts: 761
Registered: 30-12-2018
Location: not so United Kingdom
Member Is Offline
|
|
Quote: Originally posted by bnull  |
When the voltage has a component AC and a component DC (DC offset), ordinary meters measure either the AC component or the DC component but not both
at the same time. The AC+DC meter measures both and outputs this:
$$V_{RMS_{(AC+DC)}}=\sqrt{V_{DC}^2+V_{RMS_{AC}}^2}.$$
|
If you mean it performs that sum then that is incorrect. A true rms meter simple calculates the rms of the signal be it AC, DC or a combination of
both.
Notice the first multimeter (UT8802) is not a true rms meter and has modes for DC and modes for AC. In AC mode it measures the mean rectified signal
then increases it by 0.11 assuming its a sine wave. The ratio of the rms to the mean of rectified sine wave is 1.11. If you measured the rms of a +
and - square wave it would give reading 0.11 too large.
The true rms multimeters (UT8803, I don't know about UT8804) do not have different ranges for AC and DC, its not needed because they calculate the
true rms.
Modern true reading multimeters sample the signal and calculate the rms from the samples. The expensive UT8805 even provides different functions it
can perform on the samples.
[Edited on 4/5/2024 by wg48temp9]
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
|
|
|
bnull
Hazard to Others
Posts: 138
Registered: 15-1-2024
Location: Between the Atlantic and the Pacific Ocean
Member Is Online
Mood: Feeling like a pinky-bending bluesman.
|
|
| Quote: Originally posted by wg48temp9 | | If you mean it performs that sum then that is incorrect. A true rms meter simple calculates the rms of the signal be it AC, DC or a combination of
both. |
"AC+DC measurement: Measure signals with AC and DC components (including various waveforms)
Ordinary multimeters can only measure pure AC/DC signals. If the measured AC signal is mixed with the DC signal, the AC signal reading is meaningless.
For Uni-Trend’s multimeters with AC+DC function, the AC and DC components are measured together." (https://meters.uni-trend.com/faqs/acdc-measurement/)
"AC and DC are components of a complex signal.
AC Voltage means RMS Voltage for AC component (effective Voltage of alternating current).
DC Voltage means Voltage for DC component (constant Voltage offset).
Both components produce power dissipation on the applied load.
So, you're needs to sum them together in order to get effective Voltage for a total dissipated power.
AC+DC Voltage = sqrt([AC RMS Voltage]^2 + [DC Voltage]^2)" (https://www.eevblog.com/forum/beginners/can-someone-explain-...)
"If you are expecting to include the DC component, but the meter is AC coupled, the results can be dramatically wrong. As a side note, if you need to
measure a small AC signal riding on a large DC offset but your meter doesn’t provide AC + DC directly, you can measure the AC component using AC
coupling and measure the DC component separately. Then add the two using rms addition:
AC + DC =sqrt((ACrms)2+DC2)" (Make Better AC RMS Measurements with your Digital Multimeter. Application note, Keysight Technologies, 2018. There's a bloody typo in the
formula that they never bothered to fix.)
True-RMS Measurement Pt.1: AC vs. AC+DC. "Roger demonstrates the difference between so called "True-RMS" (only AC) and "True-RMS AC+DC"
multimeters and a simple AC-averaging multimeter." (https://www.youtube.com/watch?v=LZEie3nAo1E) 
That's the one in question:
[Edited on 5-4-2024 by bnull]
Quod scripsi, scripsi.
B. N. Ull
|
|
|
wg48temp9
National Hazard
Posts: 761
Registered: 30-12-2018
Location: not so United Kingdom
Member Is Offline
|
|
I have now had time to view the details of UT8804.
Below is a snip of the selection switch for the UT8804:
I think the symbol next to all the current ranges is intended to indicate mixed AC and DC signals which are measured true rms ie calculating the rms
from a set of samples of the signal DC coupled. I think some people are calling this "AC + DC" mode.
On the voltage range there or two different symbols one usually indicates AC and the other DC. I would expect the AC range to be AC coupled and
measures the RMS of the AC component. Does the DC position indicate average or rms ?
The UT8803 only uses the mixed symbol that the current ranges of the UT8804 uses. Meaning it only measures true rms DC coupled
I suspect the tick in AC+DC column for the 04 refers to the two voltage ranges, AC range and DC range that the 03 does not have.
I am very interested in these meters as they both have a usb interface. I expect to purchase the 03. If I want to measure the AC component of a mixed
AC and DC voltage l I will add a series capacitor to one of the test leads.
[Edited on 4/7/2024 by wg48temp9]
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
|
|
|
bnull
Hazard to Others
Posts: 138
Registered: 15-1-2024
Location: Between the Atlantic and the Pacific Ocean
Member Is Online
Mood: Feeling like a pinky-bending bluesman.
|
|
| Quote: Originally posted by wg48temp9 | I think the symbol next to all the current ranges is intended to indicate mixed AC and DC signals which are measured true rms ie calculating the rms
from a set of samples of the signal DC coupled. I think some people are calling this "AC + DC" mode.
On the voltage range there or two different symbols one usually indicates AC and the other DC. I would expect the AC range to be AC coupled and
measures the RMS of the AC component. Does the DC position indicate average or rms ?
The UT8803 only uses the mixed symbol that the current ranges of the UT8804 uses. Meaning it only measures true rms DC coupled
I suspect the tick in AC+DC column for the 04 refers to the two voltage ranges, AC range and DC range that the 03 does not have.
I am very interested in these meters as they both have a usb interface. I expect to purchase the 03. If I want to measure the AC component of a mixed
AC and DC voltage l I will add a series capacitor to one of the test leads.
[Edited on 4/7/2024 by wg48temp9] |
Read the UT8804E manual (http://unitrend.oss-cn-hongkong.aliyuncs.com/upload/file/202...), starting on page 9.
Quod scripsi, scripsi.
B. N. Ull
|
|
|
| Pages:
1
..
101
102
103 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
