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#3900 by jmossman on 16 Jul, 2016 00:09
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It's got to be the ADC. From the datasheet: "Provides 19.5 mV resolution" This is what makes it look 8-bit at 0.1V!
And for its $250 big brother: 10mV maximum resolution
http://www.dataq.com/resources/pdfs/datasheets/di-245ds.pdf
And its $500 bigger brother: 1.2mV at +-10V and 122µV at +-1V
http://www.dataq.com/resources/pdfs/datasheets/710ds.pdf
I'm a little surprised that the LDS "span" and "offset" controls can't help eliminate some/most of the observed flatness. Perhaps a different inline resistor value is needed?
Alternatively a small opamp circuit on a breadboard with a few variable resistors (powered by two 9V batteries) would also allow dialing in the appropriate gain (and offset) to help maximize usage of the 10-bit ADC resolution. I suspect even the bigger-brothers would benefit from a small signal amplifier.
(I mention offset since the dataq unit has a built-in opamp that scales the -10/+10V differential input range down to the 0/+3.3V range available on the AVR32 microcontroller's 10-bit ADC; the current usage of a simple inline resistor to convert amps to voltage results in an effective 9-bit ADC resolution due to creating only a 0/+10V range for sampling, which gets scaled to +1.66/+3.3V by the dataq's opamp) -
#3901 by zen-in on 16 Jul, 2016 00:15
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Do you have an audio frequency signal generator and oscilloscope? I would look at the input of the A/D when the pendulum is moving from the calibration weight. What is the peak to peak voltage? Then apply the same level signal from the signal generator; applying a ramp or triangle waveform. Look at the raw data (DN values as some call them) coming out of the A/D. That might require finding another program to read the A/D. If you display the data in a binary format you should see it increasing/decreasing monotonically; a single bit changing at a time. If you see that then maybe the software that is reading the A/D is at fault. It might be using floating point at some stage and doing smoothing or something else to corrupt your data. You should try to find out what is happening at every stage. Anything is possible. People write very buggy code today, especially if it is freeware. We are conditioned to believe anything that comes out of a computer and can be graphed is real. Most of the time it isn't.The same flattened areas are in Dave's data. You just need to zoom in to see it as with mine. It shows up at the scale 0.1V in all the data i've seen. Though it looks like using the 3um (60ms) mode may yield the best data at the level.
One thing I don't think was answered was whether these data is the result of output with a device that is smoothing the data real-time.
And if the answer is yes, whether the real-time smoothing of data can be turned off.
I think there is some real-time smoothing/rounding going on, but I'm not sure if it's the LDS or the ADC at this point. I've spent a large portion of the day trying to completely eliminate the flattened areas. The ADC is the cheapest component by far at $29 vs $1,500 for the LDS.
Here is a picture of the controls on the amp. This is all there is control-wise. -
#3902 by tleach on 16 Jul, 2016 01:56
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My answer is that where the damping factor is greater, a greater amount of momentum can be transferred than where damping factor is lower. If I use the PV Model terminology, where K is the refractive index.
p(K) = p0*sqrt(K)
If the damping is higher, K is higher. If there is asymmetry in K, then momentum transfer will also be asymmetrical. This could provide more thrust than a photon rocket, because it depends on the rate of change in K, i.e., the asymmetry. In the EM drive, damping should be highest at the small end. Right? Where attenuation is highest and the induction is highest.
Todd
So, the frustum/mode combo that produces the highest degree of asymmetry in attenuation and induction between the small and large ends should produce the most thrust? How does the distance between the end plates, the length of the asymmetric region, effect the thrust? Is a more gradual gradient over a longer distance more or less efficient at producing thrust than a more abrupt gradient (with the same level of asymmetry) over a shorter distance? -
#3903 by tleach on 16 Jul, 2016 02:01
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Is a more gradual gradient over a longer distance more or less efficient at producing thrust than a more abrupt gradient (with the same level of asymmetry) over a shorter distance?
Or is it all down to the amount of asymmetry? Perhaps the distance between endplates doesn't matter except for their relevance to the mode shapes that can be achieved (and resulting asymmetry) within the dimensions of any given frustum? -
#3904 by rfmwguy on 16 Jul, 2016 02:29
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new vid w/narration
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#3905 by dustinthewind on 16 Jul, 2016 03:21
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Is a more gradual gradient over a longer distance more or less efficient at producing thrust than a more abrupt gradient (with the same level of asymmetry) over a shorter distance?
Or is it all down to the amount of asymmetry? Perhaps the distance between endplates doesn't matter except for their relevance to the mode shapes that can be achieved (and resulting asymmetry) within the dimensions of any given frustum?
I don't know exactly what he will say. I am just "speculating" here, but my guess is that "if there is an effect of thrust", it would be down to the difference in wavelength between the wide and narrow end. My speculation suggest taking a small wavelength and stretching it out as far as you can, but without using the index of a physical dielectric. The reasoning is somewhat based on this paper in the topic below but think of the dielectric as that of a Polarizable vacuum instead. Sorry wrong link, corrected link: https://forum.nasaspaceflight.com/index.php?topic=39772.msg1548704#msg1548704 -
#3906 by Flyby on 16 Jul, 2016 08:15
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Rfmwguy,
just a wild idea, but would it be possible to solve the problem of the expanding connecting copper wires, by using a slip ring contact?
As long your torsion balance is connected with a continuous wire (looped or not), that expanding wire will cause small momentum forces on your beam because the copper wire expands off-center of the suspension wire.
that is because you have forces that are not perfectly aligned with the suspension axis. Not 100% sure, but a perpendicular slip ring (not axial) might solve that issue?
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#3907 by rfmwguy on 16 Jul, 2016 11:03
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Rfmwguy,
Good idea...once I get the PCM reflow up about 100°F higher, I will focus on the harness again. A central point pivot with a slip ring or perhaps the old galinstan liquid contacts might be in order. Hate to add resistance to the torsion beam but I'm not seeing another way as long as I'm using umbilicals.
just a wild idea, but would it be possible to solve the problem of the expanding connecting copper wires, by using a slip ring contact?
As long your torsion balance is connected with a continuous wire (looped or not), that expanding wire will cause small momentum forces on your beam because the copper wire expands off-center of the suspension wire.
that is because you have forces that are not perfectly aligned with the suspension axis. Not 100% sure, but a perpendicular slip ring (not axial) might solve that issue? -
#3908 by WarpTech on 16 Jul, 2016 12:58
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My answer is that where the damping factor is greater, a greater amount of momentum can be transferred than where damping factor is lower. If I use the PV Model terminology, where K is the refractive index.
p(K) = p0*sqrt(K)
If the damping is higher, K is higher. If there is asymmetry in K, then momentum transfer will also be asymmetrical. This could provide more thrust than a photon rocket, because it depends on the rate of change in K, i.e., the asymmetry. In the EM drive, damping should be highest at the small end. Right? Where attenuation is highest and the induction is highest.
Todd
So, the frustum/mode combo that produces the highest degree of asymmetry in attenuation and induction between the small and large ends should produce the most thrust? How does the distance between the end plates, the length of the asymmetric region, effect the thrust? Is a more gradual gradient over a longer distance more or less efficient at producing thrust than a more abrupt gradient (with the same level of asymmetry) over a shorter distance?
IMO, it would work better if the big end plate were not there. When it reflects off the small end, it again transfers momentum in the forward direction and then let the reflection out the back. Because as soon as it reflects off the big end plate, the majority of momentum gained is given back. If the attenuation and relative refractive index at the small end is larger than vacuum, it will enhance the photon rocket's performance.
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#3909 by Monomorphic on 16 Jul, 2016 13:04
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just a wild idea, but would it be possible to solve the problem of the expanding connecting copper wires, by using a slip ring contact?
Would the carbon brush used to make contact with the rings be able to handle 4kV and 10 amps? A meaty connection is needed in my experience. I instantly vaporized a 5kV HV probe because it wasn't tightly attached. -
#3910 by xyzzy on 16 Jul, 2016 13:40
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It's got to be the ADC. From the datasheet: "Provides 19.5 mV resolution" This is what makes it look 8-bit at 0.1V!
And for its $250 big brother: 10mV maximum resolution
http://www.dataq.com/resources/pdfs/datasheets/di-245ds.pdf
And its $500 bigger brother: 1.2mV at +-10V and 122µV at +-1V
http://www.dataq.com/resources/pdfs/datasheets/710ds.pdf
Given the ADC's rather poor resolution, have you considered using a multi-meter instead?
Some multi-meters (even small handheld ones) have options to allow the connection to a PC for data logging and they can provide considerably higher resolution too.
For example, a Sanwa PC7000 (http://overseas.sanwa-meter.co.jp/items/detail.php?id=13) can be set to 5 1/2 digits (500000 counts) resolution mode in the DC voltage ranges and can provide an isolated connection (via an infrared transceiver accessory) to a PC for data logging. It has a 500 mV range with single digit microvolt resolution. Also it can directly measure a 4-20 mA sensor current loop, automatically translating the measured value to a 0 - 100 % sensor reading (useful with industrial standard 4 - 20 mA sensors such as your LDS).
Admittedly it's not very fast (samples 5 times per second in 4 1/2 digit mode, 1.25 times per second in 5 1/2 digit DCV mode), but the beam is not moving very fast either It also obviously has only one input channel (being a handheld multi-meter after all), but it might be useful to add a slow high-resolution channel to the fast but low-resolution ones that you already have with the existing DATAQ.
P.S. Unfortunately a PC7000 is also in a similar price range as the more expensive DATAQ solutions. -
#3911 by WarpTech on 16 Jul, 2016 14:24
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It's got to be the ADC. From the datasheet: "Provides 19.5 mV resolution" This is what makes it look 8-bit at 0.1V!
And for its $250 big brother: 10mV maximum resolution
http://www.dataq.com/resources/pdfs/datasheets/di-245ds.pdf
And its $500 bigger brother: 1.2mV at +-10V and 122µV at +-1V
http://www.dataq.com/resources/pdfs/datasheets/710ds.pdf
Given the ADC's rather poor resolution, have you considered using a multi-meter instead?
Some multi-meters (even small handheld ones) have options to allow the connection to a PC for data logging and they can provide considerably higher resolution too.
For example, a Sanwa PC7000 (http://overseas.sanwa-meter.co.jp/items/detail.php?id=13) can be set to 5 1/2 digits (500000 counts) resolution mode in the DC voltage ranges and can provide an isolated connection (via an infrared transceiver accessory) to a PC for data logging. It has a 500 mV range with single digit microvolt resolution. Also it can directly measure a 4-20 mA sensor current loop, automatically translating the measured value to a 0 - 100 % sensor reading (useful with industrial standard 4 - 20 mA sensors such as your LDS).
Admittedly it's not very fast (samples 5 times per second in 4 1/2 digit mode, 1.25 times per second in 5 1/2 digit DCV mode), but the beam is not moving very fast either It also obviously has only one input channel (being a handheld multi-meter after all), but it might be useful to add a slow high-resolution channel to the fast but low-resolution ones that you already have with the existing DATAQ.
P.S. Unfortunately a PC7000 is also in a similar price range as the more expensive DATAQ solutions.
Great idea! Here's something not too pricey that would be much better than a DATAQ IMO. More useful too.
http://www.testequipmentdepot.com/owon/oscilloscopes/digital/virtual/25-mhz-pc-oscilloscope-usb-isolation-vds1022i.htm
They also have some relatively low cost portable o'scopes from around $350, with 2+ channels. Personally, I have an old HP 54512B 300MHz scope, rated 1 GSa/sec, with FFT in my garage that I use maybe once a year to fix a guitar pedal or something.
I picked it up on eBay for $500 in 2004. I used one at work for years, it's nice to have around.
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#3912 by rfmwguy on 16 Jul, 2016 14:39
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Valuable input Todd. I struggled with this last summer and was afraid the o'scope route with low sample rate wouldn't work. As it turns out, my momentum arm being as long as they are have my ADC sample rate at about 5...same as the scope. However, Jamie's beam is far more responsive and a faster rate would help him, closer to 20 samples/sec.It's got to be the ADC. From the datasheet: "Provides 19.5 mV resolution" This is what makes it look 8-bit at 0.1V!
And for its $250 big brother: 10mV maximum resolution
http://www.dataq.com/resources/pdfs/datasheets/di-245ds.pdf
And its $500 bigger brother: 1.2mV at +-10V and 122µV at +-1V
http://www.dataq.com/resources/pdfs/datasheets/710ds.pdf
Given the ADC's rather poor resolution, have you considered using a multi-meter instead?
Some multi-meters (even small handheld ones) have options to allow the connection to a PC for data logging and they can provide considerably higher resolution too.
For example, a Sanwa PC7000 (http://overseas.sanwa-meter.co.jp/items/detail.php?id=13) can be set to 5 1/2 digits (500000 counts) resolution mode in the DC voltage ranges and can provide an isolated connection (via an infrared transceiver accessory) to a PC for data logging. It has a 500 mV range with single digit microvolt resolution. Also it can directly measure a 4-20 mA sensor current loop, automatically translating the measured value to a 0 - 100 % sensor reading (useful with industrial standard 4 - 20 mA sensors such as your LDS).
Admittedly it's not very fast (samples 5 times per second in 4 1/2 digit mode, 1.25 times per second in 5 1/2 digit DCV mode), but the beam is not moving very fast either It also obviously has only one input channel (being a handheld multi-meter after all), but it might be useful to add a slow high-resolution channel to the fast but low-resolution ones that you already have with the existing DATAQ.
P.S. Unfortunately a PC7000 is also in a similar price range as the more expensive DATAQ solutions.
Great idea! Here's something not too pricey that would be much better than a DATAQ IMO. More useful too.
http://www.testequipmentdepot.com/owon/oscilloscopes/digital/virtual/25-mhz-pc-oscilloscope-usb-isolation-vds1022i.htm
They also have some relatively low cost portable o'scopes from around $350, with 2+ channels. Personally, I have an old HP 54512B 300MHz scope, rated 1 GSa/sec, with FFT in my garage that I use maybe once a year to fix a guitar pedal or something. I picked it up on eBay for $500 in 2004. I used one at work for years, it's nice to have around. -
#3913 by xyzzy on 16 Jul, 2016 19:15
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Great idea! Here's something not too pricey that would be much better than a DATAQ IMO. More useful too.
Valuable input Todd. I struggled with this last summer and was afraid the o'scope route with low sample rate wouldn't work. As it turns out, my momentum arm being as long as they are have my ADC sample rate at about 5...same as the scope. However, Jamie's beam is far more responsive and a faster rate would help him, closer to 20 samples/sec.
http://www.testequipmentdepot.com/owon/oscilloscopes/digital/virtual/25-mhz-pc-oscilloscope-usb-isolation-vds1022i.htm
They also have some relatively low cost portable o'scopes from around $350, with 2+ channels. Personally, I have an old HP 54512B 300MHz scope, rated 1 GSa/sec, with FFT in my garage that I use maybe once a year to fix a guitar pedal or something. I picked it up on eBay for $500 in 2004. I used one at work for years, it's nice to have around.
Please note that while scopes certainly have many useful features, DC resolution and stability are none of them. In fact, a typical scope only has 8 bits of resolution and so does the one in the link above. Even the cheapest DATAQ claims a higher resolution than that.
Oscilloscopes are optimized for acquisition speed, and the speed optimization leads to low resolutions and poor DC performance.
Here's a rough comparison of resolution abilities of various devices that are capable of measuring DC and very low frequency signals. It's not very scientific and was just put together ad-hoc, extrapolating from various published resolution specs and some "gut feeling", so please take the values with a grain of salt:
- ca. 4 bits equivalent: simple analog pointer movement ("VU meter") out of an old stereo
- ca. 5 noise-free bits out of 8 total: really cheap oscilloscope
- ca. 6 bits equivalent: typical analog pointer movement, reading by eye
- ca. 6 noise-free bits out of 8 total: typical cheap oscilloscope (less than $2000)
- ca. 7 bits equivalent: high quality analog pointer movement, taut band and mirror scale (1% class)
- ca. 7 noise-free bits out of 10 total: really cheap digital multimeter ($10)
- ca. 8 noise-free bits out of 10 total: cheap digital multimeter ($25)
- ca. 8 noise-free bits out of 10 total: mid-range oscilloscope (over $2000)
- ca. 10 noise-free bits out of 12 total: reasonable quality digital multimeter ($50)
- ca. 10 noise-free bits out of 12 total: upper mid-range oscilloscope (over $6000)
- ca. 10 to 11 noise-free bits out of 12 total: simple DATAQ
- ca. 12 noise-free bits: more expensive DATAQ
- ca. 12 noise-free bits out of 14 total: high-end oscilloscope (upscale Rohde&Schwarz model)
- ca. 13 noise-free bits out of total 15: 4 1/2 digit multimeter (Fluke 87 V, Yokogawa TY720)
- ca. 14 noise-free bits out of total 16: very high-end oscilloscope (some 5-digit price range)
- ca. 15 noise-free bits out of total 19: 5 1/2 digit multimeter (Sanwa PC7000 in extended DCV mode)
- ca. 16 noise-free bits out of total 19: 5 1/2 digit basic benchtop multimeter - Fluke, Agilent, Keithley
- ca. 18 noise-free bits out of total 21: 6 1/2 digit benchtop multimeter - Fluke, Agilent, Keithley
- ca. 25 noise-free bits out of total 29: calibration standard for metrology use (Agilent 3458A)
Please note that the listing above is very approximate. It's only intended for a very basic, approximate overview of how well various things can measure a DC voltage. Values for oscilloscope are based on single samples, not including the oversampling and averaging modes that many scopes have.
Any model names are examples only, hopefully representative for the instruments of a their respective class, the exact performance of a particular device is not implied.
But still, if the value that you want to measure is DC or very slow, the fastest acquisition speed devices will give the worst results, so one should use a meter appropriate to the signal speed in question. -
#3914 by WarpTech on 16 Jul, 2016 19:45
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...
But still, if the value that you want to measure is DC or very slow, the fastest acquisition speed devices will give the worst results, so one should use a meter appropriate to the signal speed in question.
You're correct. However, I think it has a front-end amplifier because it says it can measure 5mV/div, where the LDS is max 20mA output into 270 Ohms, limits his setup to;
20 mA * 270 Ohm = 5.4V FS where he needs 20V, and the DATAQ is limited to 19.5mV resolution at this scale, without a front-end amplifier.
The virtual scope has 4X higher resolution AND the ability to scale the input.
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#3915 by masonke on 16 Jul, 2016 21:01
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1. The EM DRIVE is just another example of why SCIENTIST and SKEPTICS have to look and test EVERY claim! Because you NEVER KNOW when the most weird claim, will be the **(NEW DISCOVERY)**!!!
2. Like the world is not flat, but round! It may not obey the CURRENT LAWS, but that is why it is called a (NEW DISCOVERY), and scientist have to investigate (ALL) claims...no matter how CRAZY they sound!
3. So many other claims and theories have NOT been investigated because they are too WEIRD, or don't fit the CURRENT laws of known science, or scientist are afraid they will be associated or called a QUACK! And I am sure, MANY NEW discoveries have been MISSED because of this backward thinking!
4. 1ST law of Science, have an *(OPEN MIND)*! And don't don't tear something down just because it is weird...as a scientist, you have to investigate EVERY THING, and find out if it is real or not...because you NEVER KNOW if this is the NEW DISCOVERY that will change EVERYTHING!! -
#3916 by Monomorphic on 17 Jul, 2016 01:47
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Build Update: New wedge-geometry emdrive completed. It is the culmination of countless hours of work and dozens of simulations. This emdrive resonates at TE203 (what looks like TE013 in the cone-frustum geometry) at 2.45Ghz. It also incorporates a small microwave waveguide.
Tomorrow I will mount the new emdrive to the torsional pendulum and begin the balancing/calibration process.
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#3917 by SteveD on 17 Jul, 2016 02:36
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Build Update: New wedge-geometry emdrive completed. It is the culmination of countless hours of work and dozens of simulations. This emdrive resonates at TE310 (what looks like TE013 in the frustum geometry) at 2.45Ghz. It also incorporates a small microwave waveguide.
Tomorrow I will mount the new emdrive to the torsional pendulum and begin the balancing/calibration process.
Does this include a dielectric insert? -
#3918 by SteveD on 17 Jul, 2016 02:47
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A thought about the idea of constant acceleration for constant power, what if we're looking at the entire idea wrong? What if we're seeing constant acceleration with a constant Q. As acceleration increases the photons undergo a greater redshift with each bounce. The power requirements to create momentum (amount of redshift the photons undergo) increases with acceleration. At the velocities involved in current EMDrive tests, the photons go to heat well before the point that the redshift becomes a concern (maybe, I still think redshift might place a practical limit on Q). This gives the illusion of constant acceleration for constant power.
Heat = Energy In - Redshift.
In effect, the efficiency of the drive increases on a bell curve as it accelerates. We are yet unclear where the peak of that curve is.
Of course, the entire thing could still just be expanding wires. -
#3919 by Monomorphic on 17 Jul, 2016 02:48
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Does this include a dielectric insert?
No. But I can tune it by using "spacer gaskets" on the small end.
I picked it up on eBay for $500 in 2004. I used one at work for years, it's nice to have around.