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#1020 by rq3 on 27 Dec, 2016 22:25
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I would also suggest that using melamine laminated fiberboard as an experimental platform may be problematic. It is extremely moisture and temperature sensitive, and will cold flow under its own weight. Since you have apparently spent tens of thousands of dollars so far, may I suggest an Invar, quartz, or Schott glass/ceramic platform (obtainable from a flat surface cooktop) rather than the material you propose?
This project is supposed to be cheap (about $500) because its goal is an easy EmDrive replication platform. Thus in order to keep the price at its lowest level, what alternative type of wood would you recommend?
For a device to measure micronewton forces, I wouldn't recommend wood of any kind. For those in the US, I would recommend going to the local dump, and snagging a glass surface cooktop. The glass ceramic surface has a coefficient of thermal expansion near zero (better than quartz), and is insensitive to moisture. Carbon fiber extrusions, if properly selected, would be another good choice, but not free of cost unless your dump is better than mine.
Doing good science on the cheap is an art. The art involves a grasp of all of the sciences. Some call this magic. Others call it obvious. -
#1021 by PotomacNeuron on 27 Dec, 2016 23:09
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Rather than publishing new drawings each time, I will update this post as we go along:
I will use a comparable setup, except that I will not use a laptop. Ideal would be to use a wireless USB connection (to control the Windfreak signal generator, and maybe to read out some sensors), but there doesn't seem to be much of that stuff around. One was from Cables to Go, still available on ebay: http://www.ebay.co.uk/itm/CABLES-TO-GO-29597-Wireless-USB-Superbooster-Extender-Kit-/190589610686
but it is only usable with XP and Vista. Do any of you know a more recent alternative for this device?
As stated previously, A better way to hang the piano wire is to tie it to the tip of the up-side-down T, as shown here. In this way the wire torque calculation is easy. Calculation is better included in the analysis.
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#1022 by Monomorphic on 27 Dec, 2016 23:13
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I would also suggest that using melamine laminated fiberboard as an experimental platform may be problematic. It is extremely moisture and temperature sensitive, and will cold flow under its own weight. Since you have apparently spent tens of thousands of dollars so far, may I suggest an Invar, quartz, or Schott glass/ceramic platform (obtainable from a flat surface cooktop) rather than the material you propose?
This project is supposed to be cheap (about $500) because its goal is an easy EmDrive replication platform. Thus in order to keep the price at its lowest level, what alternative type of wood would you recommend?
For a device to measure micronewton forces, I wouldn't recommend wood of any kind. For those in the US, I would recommend going to the local dump, and snagging a glass surface cooktop. The glass ceramic surface has a coefficient of thermal expansion near zero (better than quartz), and is insensitive to moisture. Carbon fiber extrusions, if properly selected, would be another good choice, but not free of cost unless your dump is better than mine.
The extruded aluminum T-slot channel used by NASA Eagleworks is fairly cheap.
http://www.faztek.net/t-slottedaluminum.html
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#1023 by xyzzy on 27 Dec, 2016 23:15
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Looking at the description in Dr. Chen / CAST's patents, it seems like they are trying to maintain resonance by measuring the field inside the resonant cavity through a feedback port and an RF level meter (and presumably tune the VCO for maximum measured field strength). This is somewhat similar to the Traveller's proposed method, only that he measures the reflected power and tunes for minimum reflection. Both methods have their advantages. The Traveller's method does not need a sense antenna (or if using waveguide, a sense port), therefore avoids some losses. Dr. Chen's method can (at least in principle) be made mode-selective by properly shaping the sense antenna so that it preferably picks up the field from the desired mode and rejects others, thereby providing information on whether the RF energy is really exciting the correct mode or not and allowing a more mode-specific tuning.
Both methods however may still have a potential problem with respect to frequency stability. They both need a periodic sweeping (or rather "wobbling") of the frequency in order to find out, where the resonance currently stands. This comes from the fact that neither an SWR meter nor a simple level meter connected to a sense antenna can tell whether the current frequency is above or below resonance. One can see that the SWR increases, but one does not see in which direction to adjust the VCO, therefore one has to basically try adjusting it in some direction, and if the SWR increases again, rather than decreases, the direction was wrong and needs to be reversed. Therefore, in a long term steady-state operation, a control algorithm based on these principles will always slightly oscillate around the optimal VCO frequency, rather holding it completely stable. For fully stable operation, one would need not only the SWR / field strength level at any one instant, but also simultaneous information on the direction where to tune the VCO. Even my previously proposed method of using a PLL together with a phase modulator is not completely immune to this problem - although a good PLL would automatically maintain the best possible frequency with no need for intentionally introduced wobbling, the phase information used to drive the phase modulation circuitry would still have to come from trial and error - increase the phase, look at the SWR, and if the SWR went up, that was the wrong direction.
Again, something entirely different would need to be done in order to get rid of the frequency wobbling and the trial-and-error method of frequency control altogether, and this something would need a direction signal as to where the resonance is. In order to get the measurement capability for this direction signal, I'd like to propose a slightly different frequency synthesis setup.
Rather than using one single signal at the target RF frequency only, it should be possible to also inject two additional sidetones into the RF path. The sidetones need to be located symmetrically very close to the center frequency, one of them below, the other above. They do not need to be very strong in power, probably something like 5% power for each sidetone and 90% power for the main signal should be good enough for all practical purposes. The composite signal would then be injected into the resonating cavity, and a sense antenna (or a sense port if using waveguide rather than coax) would be used to get the feedback signal from inside in a similar way to Dr. Chen's. However rather than looking at the total RF power from the sense signal with a simple RMS type RF power meter, one would separate out both sidetones individually, while suppressing the center frequency, and measure the RF power in each sidetone by itself. Most likely one would also use a logarithmic measure for sidetone powers for practical reasons of RF engineering. If the center frequency is slightly off resonance, one of the sidetones would be closer to resonance than the other (given that they are symmetrically spaced around the center frequency) and therefore its respective signal from the sense antenna would be stronger. The measurement, which of the sidetones, upper or lower, is stronger than the other provides the information whether the center frequency is too low or too high. With a well-centered system being driven exactly on resonance, both sidetones would be the same distance from SRF in opposite directions, and therefore essentially equal in magnitude.
Now having a sidetone level difference signal that is mathematically a signed (rather than unsigned) quantity, it should be possible to use traditional and well understood methods of PID control in order to control the VCO frequency. This should make the control algorithms more amenable to known analytical approaches from control theory, and in the longer term more robust. Less heuristics on the part of the control algorithms should be needed, and also the frequency could possibly be maintained to a higher degree of stability, without the need for periodic sweeping or wobbling.
Attached is a block diagram of the proposed system. The sidetones can be created via amplitude modulation of the carrier, and the detection would probably need something like a single-sideband radio receiver, only that it would receive both sidebands simultaneously and provide each of them on a separate output (USB for upper sideband and LSB for lower sideband on the block diagram). Because the level measurement is fully ratiometric (linear-in-dB level difference between USB and LSB sidetones), the absolute signal level is not critically important. For a more accurate and reliable operation of the receivers and level meters, it can therefore be normalized to a fixed and known level by an AGC circuit in the common input path.
While this approach will likely be seen as somewhat too complex for many DIY EMdrive builders, I hope that it can still at least provide some new ideas towards a more stable frequency synthesis.
P.S. Since this was designed to be a potential improvement of Dr. Chen's frequency stabilization method, maybe oyzw or someone with the contact info should forward this post to Dr. Chen too...
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#1024 by PotomacNeuron on 27 Dec, 2016 23:31
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I would also suggest that using melamine laminated fiberboard as an experimental platform may be problematic. It is extremely moisture and temperature sensitive, and will cold flow under its own weight. Since you have apparently spent tens of thousands of dollars so far, may I suggest an Invar, quartz, or Schott glass/ceramic platform (obtainable from a flat surface cooktop) rather than the material you propose?
This project is supposed to be cheap (about $500) because its goal is an easy EmDrive replication platform. Thus in order to keep the price at its lowest level, what alternative type of wood would you recommend?
For a device to measure micronewton forces, I wouldn't recommend wood of any kind. For those in the US, I would recommend going to the local dump, and snagging a glass surface cooktop. The glass ceramic surface has a coefficient of thermal expansion near zero (better than quartz), and is insensitive to moisture. Carbon fiber extrusions, if properly selected, would be another good choice, but not free of cost unless your dump is better than mine.
The extruded aluminum T-slot channel used by NASA Eagleworks is fairly cheap.
http://www.faztek.net/t-slottedaluminum.html
The original choice of wood is to avoid any chance of overlooked ground loop. Re-introducing aluminium may lead to the same problem as EW's 2014 paper had : DC ground loop. Wood is not a bad choice. -
#1025 by rq3 on 27 Dec, 2016 23:35
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Looking at the description in Dr. Chen / CAST's patents, it seems like they are trying to maintain resonance by measuring the field inside the resonant cavity through a feedback port and an RF level meter (and presumably tune the VCO for maximum measured field strength). This is somewhat similar to the Traveller's proposed method, only that he measures the reflected power and tunes for minimum reflection. Both methods have their advantages. The Traveller's method does not need a sense antenna (or if using waveguide, a sense port), therefore avoids some losses. Dr. Chen's method can (at least in principle) be made mode-selective by properly shaping the sense antenna so that it preferably picks up the field from the desired mode and rejects others, thereby providing information on whether the RF energy is really exciting the correct mode or not and allowing a more mode-specific tuning.
Both methods however may still have a potential problem with respect to frequency stability. They both need a periodic sweeping (or rather "wobbling") of the frequency in order to find out, where the resonance currently stands. This comes from the fact that neither an SWR meter nor a simple level meter connected to a sense antenna can tell whether the current frequency is above or below resonance. One can see that the SWR increases, but one does not see in which direction to adjust the VCO, therefore one has to basically try adjusting it in some direction, and if the SWR increases again, rather than decreases, the direction was wrong and needs to be reversed. Therefore, in a long term steady-state operation, a control algorithm based on these principles will always slightly oscillate around the optimal VCO frequency, rather holding it completely stable. For fully stable operation, one would need not only the SWR / field strength level at any one instant, but also simultaneous information on the direction where to tune the VCO. Even my previously proposed method of using a PLL together with a phase modulator is not completely immune to this problem - although a good PLL would automatically maintain the best possible frequency with no need for intentionally introduced wobbling, the phase information used to drive the phase modulation circuitry would still have to come from trial and error - increase the phase, look at the SWR, and if the SWR went up, that was the wrong direction.
Again, something entirely different would need to be done in order to get rid of the frequency wobbling and the trial-and-error method of frequency control altogether, and this something would need a direction signal as to where the resonance is. In order to get the measurement capability for this direction signal, I'd like to propose a slightly different frequency synthesis setup.
Rather than using one single signal at the target RF frequency only, it should be possible to also inject two additional sidetones into the RF path. The sidetones need to be located symmetrically very close to the center frequency, one of them below, the other above. They do not need to be very strong in power, probably something like 5% power for each sidetone and 90% power for the main signal should be good enough for all practical purposes. The composite signal would then be injected into the resonating cavity, and a sense antenna (or a sense port if using waveguide rather than coax) would be used to get the feedback signal from inside in a similar way to Dr. Chen's. However rather than looking at the total RF power from the sense signal with a simple RMS type RF power meter, one would separate out both sidetones individually, while suppressing the center frequency, and measure the RF power in each sidetone by itself. Most likely one would also use a logarithmic measure for sidetone powers for practical reasons of RF engineering. If the center frequency is slightly off resonance, one of the sidetones would be closer to resonance than the other (given that they are symmetrically spaced around the center frequency) and therefore its respective signal from the sense antenna would be stronger. The measurement, which of the sidetones, upper or lower, is stronger than the other provides the information whether the center frequency is too low or too high. With a well-centered system being driven exactly on resonance, both sidetones would be the same distance from SRF in opposite directions, and therefore essentially equal in magnitude.
Now having a sidetone level difference signal that is mathematically a signed (rather than unsigned) quantity, it should be possible to use traditional and well understood methods of PID control in order to control the VCO frequency. This should make the control algorithms more amenable to known analytical approaches from control theory, and in the longer term more robust. Less heuristics on the part of the control algorithms should be needed, and also the frequency could possibly be maintained to a higher degree of stability, without the need for periodic sweeping or wobbling.
Attached is a block diagram of the proposed system. The sidetones can be created via amplitude modulation of the carrier, and the detection would probably need something like a single-sideband radio receiver, only that it would receive both sidebands simultaneously and provide each of them on a separate output (USB for upper sideband and LSB for lower sideband on the block diagram). Because the level measurement is fully ratiometric (linear-in-dB level difference between USB and LSB sidetones), the absolute signal level is not critically important. For a more accurate and reliable operation of the receivers and level meters, it can therefore be normalized to a fixed and known level by an AGC circuit in the common input path.
While this approach will likely be seen as somewhat too complex for many DIY EMdrive builders, I hope that it can still at least provide some new ideas towards a more stable frequency synthesis.
P.S. Since this was designed to be a potential improvement of Dr. Chen's frequency stabilization method, maybe oyzw or someone with the contact info should forward this post to Dr. Chen too...
You describe a microwave carrier with low level amplitude modulation. A good spectrum analyzer will see this already as an artifact of the line powered supply, unless the microwave source is strictly battery powered. -
#1026 by PotomacNeuron on 27 Dec, 2016 23:38
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Looking at the description in Dr. Chen / CAST's patents, it seems like they are trying to maintain resonance by measuring the field inside the resonant cavity through a feedback port and an RF level meter (and presumably tune the VCO for maximum measured field strength). This is somewhat similar to the Traveller's proposed method, only that he measures the reflected power and tunes for minimum reflection. Both methods have their advantages. The Traveller's method does not need a sense antenna (or if using waveguide, a sense port), therefore avoids some losses. Dr. Chen's method can (at least in principle) be made mode-selective by properly shaping the sense antenna so that it preferably picks up the field from the desired mode and rejects others, thereby providing information on whether the RF energy is really exciting the correct mode or not and allowing a more mode-specific tuning.
Both methods however may still have a potential problem with respect to frequency stability. They both need a periodic sweeping (or rather "wobbling") of the frequency in order to find out, where the resonance currently stands. This comes from the fact that neither an SWR meter nor a simple level meter connected to a sense antenna can tell whether the current frequency is above or below resonance. One can see that the SWR increases, but one does not see in which direction to adjust the VCO, therefore one has to basically try adjusting it in some direction, and if the SWR increases again, rather than decreases, the direction was wrong and needs to be reversed. Therefore, in a long term steady-state operation, a control algorithm based on these principles will always slightly oscillate around the optimal VCO frequency, rather holding it completely stable. For fully stable operation, one would need not only the SWR / field strength level at any one instant, but also simultaneous information on the direction where to tune the VCO. Even my previously proposed method of using a PLL together with a phase modulator is not completely immune to this problem - although a good PLL would automatically maintain the best possible frequency with no need for intentionally introduced wobbling, the phase information used to drive the phase modulation circuitry would still have to come from trial and error - increase the phase, look at the SWR, and if the SWR went up, that was the wrong direction.
Again, something entirely different would need to be done in order to get rid of the frequency wobbling and the trial-and-error method of frequency control altogether, and this something would need a direction signal as to where the resonance is. In order to get the measurement capability for this direction signal, I'd like to propose a slightly different frequency synthesis setup.
Rather than using one single signal at the target RF frequency only, it should be possible to also inject two additional sidetones into the RF path. The sidetones need to be located symmetrically very close to the center frequency, one of them below, the other above. They do not need to be very strong in power, probably something like 5% power for each sidetone and 90% power for the main signal should be good enough for all practical purposes. The composite signal would then be injected into the resonating cavity, and a sense antenna (or a sense port if using waveguide rather than coax) would be used to get the feedback signal from inside in a similar way to Dr. Chen's. However rather than looking at the total RF power from the sense signal with a simple RMS type RF power meter, one would separate out both sidetones individually, while suppressing the center frequency, and measure the RF power in each sidetone by itself. Most likely one would also use a logarithmic measure for sidetone powers for practical reasons of RF engineering. If the center frequency is slightly off resonance, one of the sidetones would be closer to resonance than the other (given that they are symmetrically spaced around the center frequency) and therefore its respective signal from the sense antenna would be stronger. The measurement, which of the sidetones, upper or lower, is stronger than the other provides the information whether the center frequency is too low or too high. With a well-centered system being driven exactly on resonance, both sidetones would be the same distance from SRF in opposite directions, and therefore essentially equal in magnitude.
Now having a sidetone level difference signal that is mathematically a signed (rather than unsigned) quantity, it should be possible to use traditional and well understood methods of PID control in order to control the VCO frequency. This should make the control algorithms more amenable to known analytical approaches from control theory, and in the longer term more robust. Less heuristics on the part of the control algorithms should be needed, and also the frequency could possibly be maintained to a higher degree of stability, without the need for periodic sweeping or wobbling.
Attached is a block diagram of the proposed system. The sidetones can be created via amplitude modulation of the carrier, and the detection would probably need something like a single-sideband radio receiver, only that it would receive both sidebands simultaneously and provide each of them on a separate output (USB for upper sideband and LSB for lower sideband on the block diagram). Because the level measurement is fully ratiometric (linear-in-dB level difference between USB and LSB sidetones), the absolute signal level is not critically important. For a more accurate and reliable operation of the receivers and level meters, it can therefore be normalized to a fixed and known level by an AGC circuit in the common input path.
While this approach will likely be seen as somewhat too complex for many DIY EMdrive builders, I hope that it can still at least provide some new ideas towards a more stable frequency synthesis.
P.S. Since this was designed to be a potential improvement of Dr. Chen's frequency stabilization method, maybe oyzw or someone with the contact info should forward this post to Dr. Chen too...
I think the PLL system EW used in their 2016 looks good -- though Mr. March said he needed to tune it constantly. Maybe some improvement over their system can be made. -
#1027 by rq3 on 27 Dec, 2016 23:43
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I would also suggest that using melamine laminated fiberboard as an experimental platform may be problematic. It is extremely moisture and temperature sensitive, and will cold flow under its own weight. Since you have apparently spent tens of thousands of dollars so far, may I suggest an Invar, quartz, or Schott glass/ceramic platform (obtainable from a flat surface cooktop) rather than the material you propose?
This project is supposed to be cheap (about $500) because its goal is an easy EmDrive replication platform. Thus in order to keep the price at its lowest level, what alternative type of wood would you recommend?
For a device to measure micronewton forces, I wouldn't recommend wood of any kind. For those in the US, I would recommend going to the local dump, and snagging a glass surface cooktop. The glass ceramic surface has a coefficient of thermal expansion near zero (better than quartz), and is insensitive to moisture. Carbon fiber extrusions, if properly selected, would be another good choice, but not free of cost unless your dump is better than mine.
The extruded aluminum T-slot channel used by NASA Eagleworks is fairly cheap.
http://www.faztek.net/t-slottedaluminum.html
The original choice of wood is to avoid any chance of overlooked ground loop. Re-introducing aluminium may lead to the same problem as EW's 2014 paper had : DC ground loop. Wood is not a bad choice.
Wood is a terrible choice. It has a phenomenal ability to respond to atmospheric humidity. It is not thermally stable. For replication purposes, each individual piece of wood, of whatever species, is not replicable. The moisture level of wood is industrially tested with an electical resistance meter. So...you propose building a micronewton torsion balance using a material that responds wildly and unpredicatably to moisture, temperature, atmospheric pressure (the wood cells expand and contract), and also has an electical conductivity that varies with relative humidity.
Frankly, if you get any results, I'd laugh at them based on your choice of an uncontrollable material. -
#1028 by rq3 on 27 Dec, 2016 23:49
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Looking at the description in Dr. Chen / CAST's patents, it seems like they are trying to maintain resonance by measuring the field inside the resonant cavity through a feedback port and an RF level meter (and presumably tune the VCO for maximum measured field strength). This is somewhat similar to the Traveller's proposed method, only that he measures the reflected power and tunes for minimum reflection. Both methods have their advantages. The Traveller's method does not need a sense antenna (or if using waveguide, a sense port), therefore avoids some losses. Dr. Chen's method can (at least in principle) be made mode-selective by properly shaping the sense antenna so that it preferably picks up the field from the desired mode and rejects others, thereby providing information on whether the RF energy is really exciting the correct mode or not and allowing a more mode-specific tuning.
Both methods however may still have a potential problem with respect to frequency stability. They both need a periodic sweeping (or rather "wobbling") of the frequency in order to find out, where the resonance currently stands. This comes from the fact that neither an SWR meter nor a simple level meter connected to a sense antenna can tell whether the current frequency is above or below resonance. One can see that the SWR increases, but one does not see in which direction to adjust the VCO, therefore one has to basically try adjusting it in some direction, and if the SWR increases again, rather than decreases, the direction was wrong and needs to be reversed. Therefore, in a long term steady-state operation, a control algorithm based on these principles will always slightly oscillate around the optimal VCO frequency, rather holding it completely stable. For fully stable operation, one would need not only the SWR / field strength level at any one instant, but also simultaneous information on the direction where to tune the VCO. Even my previously proposed method of using a PLL together with a phase modulator is not completely immune to this problem - although a good PLL would automatically maintain the best possible frequency with no need for intentionally introduced wobbling, the phase information used to drive the phase modulation circuitry would still have to come from trial and error - increase the phase, look at the SWR, and if the SWR went up, that was the wrong direction.
Again, something entirely different would need to be done in order to get rid of the frequency wobbling and the trial-and-error method of frequency control altogether, and this something would need a direction signal as to where the resonance is. In order to get the measurement capability for this direction signal, I'd like to propose a slightly different frequency synthesis setup.
Rather than using one single signal at the target RF frequency only, it should be possible to also inject two additional sidetones into the RF path. The sidetones need to be located symmetrically very close to the center frequency, one of them below, the other above. They do not need to be very strong in power, probably something like 5% power for each sidetone and 90% power for the main signal should be good enough for all practical purposes. The composite signal would then be injected into the resonating cavity, and a sense antenna (or a sense port if using waveguide rather than coax) would be used to get the feedback signal from inside in a similar way to Dr. Chen's. However rather than looking at the total RF power from the sense signal with a simple RMS type RF power meter, one would separate out both sidetones individually, while suppressing the center frequency, and measure the RF power in each sidetone by itself. Most likely one would also use a logarithmic measure for sidetone powers for practical reasons of RF engineering. If the center frequency is slightly off resonance, one of the sidetones would be closer to resonance than the other (given that they are symmetrically spaced around the center frequency) and therefore its respective signal from the sense antenna would be stronger. The measurement, which of the sidetones, upper or lower, is stronger than the other provides the information whether the center frequency is too low or too high. With a well-centered system being driven exactly on resonance, both sidetones would be the same distance from SRF in opposite directions, and therefore essentially equal in magnitude.
Now having a sidetone level difference signal that is mathematically a signed (rather than unsigned) quantity, it should be possible to use traditional and well understood methods of PID control in order to control the VCO frequency. This should make the control algorithms more amenable to known analytical approaches from control theory, and in the longer term more robust. Less heuristics on the part of the control algorithms should be needed, and also the frequency could possibly be maintained to a higher degree of stability, without the need for periodic sweeping or wobbling.
Attached is a block diagram of the proposed system. The sidetones can be created via amplitude modulation of the carrier, and the detection would probably need something like a single-sideband radio receiver, only that it would receive both sidebands simultaneously and provide each of them on a separate output (USB for upper sideband and LSB for lower sideband on the block diagram). Because the level measurement is fully ratiometric (linear-in-dB level difference between USB and LSB sidetones), the absolute signal level is not critically important. For a more accurate and reliable operation of the receivers and level meters, it can therefore be normalized to a fixed and known level by an AGC circuit in the common input path.
While this approach will likely be seen as somewhat too complex for many DIY EMdrive builders, I hope that it can still at least provide some new ideas towards a more stable frequency synthesis.
P.S. Since this was designed to be a potential improvement of Dr. Chen's frequency stabilization method, maybe oyzw or someone with the contact info should forward this post to Dr. Chen too...
I think the PLL system EW used in their 2016 looks good -- though Mr. March said he needed to tune it constantly. Maybe some improvement over their system can be made.
The effect you all are looking for is NOT minimum VSWR for a particular microwave input, its maximum FORCE for a particular microwave input. As I've said ad nauseum, why does no one tune for that? Once the phase locked loop is in place, making it a force locked loop is trivial. Can no-one think outside the box? -
#1029 by PotomacNeuron on 27 Dec, 2016 23:51
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I would also suggest that using melamine laminated fiberboard as an experimental platform may be problematic. It is extremely moisture and temperature sensitive, and will cold flow under its own weight. Since you have apparently spent tens of thousands of dollars so far, may I suggest an Invar, quartz, or Schott glass/ceramic platform (obtainable from a flat surface cooktop) rather than the material you propose?
This project is supposed to be cheap (about $500) because its goal is an easy EmDrive replication platform. Thus in order to keep the price at its lowest level, what alternative type of wood would you recommend?
For a device to measure micronewton forces, I wouldn't recommend wood of any kind. For those in the US, I would recommend going to the local dump, and snagging a glass surface cooktop. The glass ceramic surface has a coefficient of thermal expansion near zero (better than quartz), and is insensitive to moisture. Carbon fiber extrusions, if properly selected, would be another good choice, but not free of cost unless your dump is better than mine.
The extruded aluminum T-slot channel used by NASA Eagleworks is fairly cheap.
http://www.faztek.net/t-slottedaluminum.html
The original choice of wood is to avoid any chance of overlooked ground loop. Re-introducing aluminium may lead to the same problem as EW's 2014 paper had : DC ground loop. Wood is not a bad choice.
Wood is a terrible choice. It has a phenomenal ability to respond to atmospheric humidity. It is not thermally stable. For replication purposes, each individual piece of wood, of whatever species, is not replicable. The moisture level of wood is industrially tested with an electical resistance meter. So...you propose building a micronewton torsion balance using a material that responds wildly and unpredicatably to moisture, temperature, atmospheric pressure (the wood cells expand and contract), and also has an electical conductivity that varies with relative humidity.
Frankly, if you get any results, I'd laugh at them based on your choice of an uncontrollable material.
I predict there is no thrust. Also any of the phenomenons you described can't happen in mili-second, or even second scale. No, it will not affect the results. But It does not hurt to choose other types of non-conductive material, eg, fiber glass rod. Aluminum should not be used, unless the purpose is not scientific. -
#1030 by PotomacNeuron on 27 Dec, 2016 23:52
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The effect you all are looking for is NOT minimum VSWR for a particular microwave input, its maximum FORCE for a particular microwave input. As I've said ad nauseum, why does no one tune for that? Once the phase locked loop is in place, making it a force locked loop is trivial. Can no-one think outside the box?
You did not count the one possible result ---- that there is no force. -
#1031 by rq3 on 27 Dec, 2016 23:59
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The effect you all are looking for is NOT minimum VSWR for a particular microwave input, its maximum FORCE for a particular microwave input. As I've said ad nauseum, why does no one tune for that? Once the phase locked loop is in place, making it a force locked loop is trivial. Can no-one think outside the box?
You did not count the one possible result ---- that there is no force.
Of course I did. Anyone who has closed loop experience knows that if the loop cannot lock, it will hunt and fail to lock. If there is no force, the control signal will either go to infinity, or it will go to zero (or an offset zero) with no measurable thrust, depending on the loop gain. -
#1032 by Monomorphic on 28 Dec, 2016 00:01
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The original choice of wood is to avoid any chance of overlooked ground loop. Re-introducing aluminium may lead to the same problem as EW's 2014 paper had : DC ground loop. Wood is not a bad choice.
If wood is preferred, I would go with a reinforced structure instead of a thin plank. The reinforced strucutre will not bend down at the ends due to gravity.
Personally, I would go with an extruded aluminum rectangular bar - which is what I used in my build. A piece long enough will run you $50 at your local metal supplier.
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#1033 by rq3 on 28 Dec, 2016 00:06
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The original choice of wood is to avoid any chance of overlooked ground loop. Re-introducing aluminium may lead to the same problem as EW's 2014 paper had : DC ground loop. Wood is not a bad choice.
If wood is preferred, I would go with a reinforced structure instead of a thin plank. It will bend down on the ends due to gravity.
Personally, I would go with an extruded aluminum rectangular bar - which is what I used in my build. A piece long enough will run you $50 at your local metal supplier.
Anyone contemplating building a torsion pendulum might consider going to their local music store, buying the thinnest guitar string available (0.008 inches diameter), nailing one end to a floor rafter in the basement, and hanging a heavy weight from the end. Just to get a feel for the system dynamics involved. A $1 experiment. -
#1034 by Donosauro on 28 Dec, 2016 00:20
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The original choice of wood is to avoid any chance of overlooked ground loop. Re-introducing aluminium may lead to the same problem as EW's 2014 paper had : DC ground loop. Wood is not a bad choice.
If wood is preferred, I would go with a reinforced structure instead of a thin plank. It will bend down on the ends due to gravity.
Personally, I would go with an extruded aluminum rectangular bar - which is what I used in my build. A piece long enough will run you $50 at your local metal supplier.
Anyone contemplating building a torsion pendulum might consider going to their local music store, buying the thinnest guitar string available (0.008 inches diameter), nailing one end to a floor rafter in the basement, and hanging a heavy weight from the end. Just to get a feel for the system dynamics involved. A $1 experiment.
And, in case you are not near a music store but are near a hobby shop, try there for the music wire. -
#1035 by Monomorphic on 28 Dec, 2016 00:22
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Anyone contemplating building a torsion pendulum might consider going to their local music store, buying the thinnest guitar string available (0.008 inches diameter), nailing one end to a floor rafter in the basement, and hanging a heavy weight from the end. Just to get a feel for the system dynamics involved. A $1 experiment.
The dynamics are very complex. Especially when one begins changing the orientation of the frustum. I eventually had to develop a weighted system for quick balancing between different orientations.
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#1036 by BitBanger on 28 Dec, 2016 00:33
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I would also suggest that using melamine laminated fiberboard as an experimental platform may be problematic. It is extremely moisture and temperature sensitive, and will cold flow under its own weight. Since you have apparently spent tens of thousands of dollars so far, may I suggest an Invar, quartz, or Schott glass/ceramic platform (obtainable from a flat surface cooktop) rather than the material you propose?
This project is supposed to be cheap (about $500) because its goal is an easy EmDrive replication platform. Thus in order to keep the price at its lowest level, what alternative type of wood would you recommend?
For a device to measure micronewton forces, I wouldn't recommend wood of any kind. For those in the US, I would recommend going to the local dump, and snagging a glass surface cooktop. The glass ceramic surface has a coefficient of thermal expansion near zero (better than quartz), and is insensitive to moisture. Carbon fiber extrusions, if properly selected, would be another good choice, but not free of cost unless your dump is better than mine.
The extruded aluminum T-slot channel used by NASA Eagleworks is fairly cheap.
http://www.faztek.net/t-slottedaluminum.html
The original choice of wood is to avoid any chance of overlooked ground loop. Re-introducing aluminium may lead to the same problem as EW's 2014 paper had : DC ground loop. Wood is not a bad choice.
Wood is a terrible choice. It has a phenomenal ability to respond to atmospheric humidity. It is not thermally stable. For replication purposes, each individual piece of wood, of whatever species, is not replicable. The moisture level of wood is industrially tested with an electical resistance meter. So...you propose building a micronewton torsion balance using a material that responds wildly and unpredicatably to moisture, temperature, atmospheric pressure (the wood cells expand and contract), and also has an electical conductivity that varies with relative humidity.
Frankly, if you get any results, I'd laugh at them based on your choice of an uncontrollable material.
Look for a local supply of a product called AZEK. It is extruded PVC that comes in a variety of sizes and shapes. It is quite stiff but cuts easily.
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#1037 by rfmwguy on 28 Dec, 2016 00:36
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That would be a total waste of mass to suggest a ceramic plate as a torsion beam.I would also suggest that using melamine laminated fiberboard as an experimental platform may be problematic. It is extremely moisture and temperature sensitive, and will cold flow under its own weight. Since you have apparently spent tens of thousands of dollars so far, may I suggest an Invar, quartz, or Schott glass/ceramic platform (obtainable from a flat surface cooktop) rather than the material you propose?
This project is supposed to be cheap (about $500) because its goal is an easy EmDrive replication platform. Thus in order to keep the price at its lowest level, what alternative type of wood would you recommend?
For a device to measure micronewton forces, I wouldn't recommend wood of any kind. For those in the US, I would recommend going to the local dump, and snagging a glass surface cooktop. The glass ceramic surface has a coefficient of thermal expansion near zero (better than quartz), and is insensitive to moisture. Carbon fiber extrusions, if properly selected, would be another good choice, but not free of cost unless your dump is better than mine.
Doing good science on the cheap is an art. The art involves a grasp of all of the sciences. Some call this magic. Others call it obvious.
Seal the hardwood beam, isolate it from direct heating and use an ir sensor to monitor beam temp during power on.
Get some positive results? Then move to improving a test stand. Keep mass as low as possible, a thinner torsion wire is always better. Heavier assembly? Thicker wire.
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#1038 by rq3 on 28 Dec, 2016 00:45
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That would be a total waste of mass to suggest a ceramic plate as a torsion beam.I would also suggest that using melamine laminated fiberboard as an experimental platform may be problematic. It is extremely moisture and temperature sensitive, and will cold flow under its own weight. Since you have apparently spent tens of thousands of dollars so far, may I suggest an Invar, quartz, or Schott glass/ceramic platform (obtainable from a flat surface cooktop) rather than the material you propose?
This project is supposed to be cheap (about $500) because its goal is an easy EmDrive replication platform. Thus in order to keep the price at its lowest level, what alternative type of wood would you recommend?
For a device to measure micronewton forces, I wouldn't recommend wood of any kind. For those in the US, I would recommend going to the local dump, and snagging a glass surface cooktop. The glass ceramic surface has a coefficient of thermal expansion near zero (better than quartz), and is insensitive to moisture. Carbon fiber extrusions, if properly selected, would be another good choice, but not free of cost unless your dump is better than mine.
Doing good science on the cheap is an art. The art involves a grasp of all of the sciences. Some call this magic. Others call it obvious.
Seal the hardwood beam, isolate it from direct heating and use an ir sensor to monitor beam temp during power on.
Get some positive results? Then move to improving a test stand. Keep mass as low as possible, a thinner torsion wire is always better. Heavier assembly? Thicker wire.
What is meant by "waste of mass"? In the case of a torsion pendulum, increased mass can only slow (provide a first order low pass filter response) to the pendulum. This may be good, it may be bad, depending on the required response. Using a material that changes mass under condtions which are uncontrollable for the home experimenter (wood, or any other material) that expands and contracts under variations in atmospheric pressure, temperature, and humidity, is ludicrous. -
#1039 by PotomacNeuron on 28 Dec, 2016 00:48
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That would be a total waste of mass to suggest a ceramic plate as a torsion beam.I would also suggest that using melamine laminated fiberboard as an experimental platform may be problematic. It is extremely moisture and temperature sensitive, and will cold flow under its own weight. Since you have apparently spent tens of thousands of dollars so far, may I suggest an Invar, quartz, or Schott glass/ceramic platform (obtainable from a flat surface cooktop) rather than the material you propose?
This project is supposed to be cheap (about $500) because its goal is an easy EmDrive replication platform. Thus in order to keep the price at its lowest level, what alternative type of wood would you recommend?
For a device to measure micronewton forces, I wouldn't recommend wood of any kind. For those in the US, I would recommend going to the local dump, and snagging a glass surface cooktop. The glass ceramic surface has a coefficient of thermal expansion near zero (better than quartz), and is insensitive to moisture. Carbon fiber extrusions, if properly selected, would be another good choice, but not free of cost unless your dump is better than mine.
Doing good science on the cheap is an art. The art involves a grasp of all of the sciences. Some call this magic. Others call it obvious.
Seal the hardwood beam, isolate it from direct heating and use an ir sensor to monitor beam temp during power on.
Get some positive results? Then move to improving a test stand. Keep mass as low as possible, a thinner torsion wire is always better. Heavier assembly? Thicker wire.
What is meant by "waste of mass"? In the case of a torsion pendulum, increased mass can only slow (provide a first order low pass filter response) to the pendulum. This may be good, it may be bad, depending on the required response. Using a material that changes mass under condtions which are uncontrollable for the home experimenter (wood, or any other material) that expands and contracts under variations in atmospheric pressure, temperature, and humidity, is ludicrous.
Wood has another benefit as being easy to work with. Screw anything to it? just use a screw. You do not even need to drill a hole first.