Mohammad_Pirzadi
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it means you have no practical idea???As commercial devices to do this already exist, your best bet is to research those.
As they probably represent a fair bit of experimental research and development, its unlikely that you are going to achieve or discover some better solution.
The research may have been done "in house" in which case you probably may not be able to discover much.
If you are really lucky it may have been part of someone’s thesis and its all there ready to scoop up if you can find it.
Well no.it means you have no practical idea???
oh thanks. I also have fair information about underground locating. my professional field is in photonic and electro-optic logic devices and I published 2 articles in IEEE and some in Iranian conferences. the latest was published in IEEE photonics technology letter.you can find them at ieeexplore.Well no.
I am almost seventy years old and have completed more than a few really interesting R&D projects over the years.
But so far I have never found the need to design a transmitter for a pipeline pig.
I believe many Edaboard members have practical ideas, me too. The basic problem seems to me that you are starting the project without much clue about magnetic and electromagnetic fields.do you have any functional idea??? I'm so tired by this project but I must complete it till February 2017
I believe many Edaboard members have practical ideas, me too. The basic problem seems to me that you are starting the project without much clue about magnetic and electromagnetic fields.
The linked manufacturer article gives a basic idea of achieved range of commercial pipeline pigging systems, it also shows the field orientation used by the devices (in case it was not obvious for you before). There are also catalog data from many other vendors with battery life, transmitter size and free air range information available on the internet.
Based on the available information you should be able to define the parameters of your planned transmitter, make calculations of expected field strength in- and outside a steel tube, specify the required sensitivity of the receiver circuit. I assume that your project is somehow related to oil and gas industry and that someone has already electromagnetic pigging systems. If so, consider measurements of transmitter field strength and receiver sensitivity of the "competitor" systems.
I mentioned that the project seems feasible. But it requires profound knowledge in analog circuit and electromagnetic design to achieve the specifications.
You are harping on about inductive wireless power transfer systems. There are some similarities, particularly that transmitter and receiver are using coils in a resonant circuit. But there's isn't much power transfer possible, just a very small remainder of the field inside the tube "leaking" to the outside. In so far the reference to WPT systems doesn't get you anywhere.
thanks. you are the best.The physics behind magnetic pig localization is probably simple compared to photonic devices. A rotational symmetric, pure AC magnetic problem, can be solved by 2.5-D FEM tools like Quickfield. There might be even research articles or project reports that calculate the basic parameters, unfortunately I didn't find any.
I hope there's someone at your institute who can help you with the magnetic calculations.
As has been explained a few times already, the wireless power transmission is a poor example to build on. You don't want a rectifier on the secondary, that would kill your sensitivity. Instead the receiver should have resonant filter > low noise amplifier > antialiasing filter > ADC. The transmit circuit could be built similar to a wireless power transmitter, but simpler (just an Hbridge driving a series LC).
Please don't keep opening new threads on the same topic.
1. The coils and capacitors have to make the coils resonant at 22Hz. Use the formula: 22 = 1/(2*Pi * Sqrt(L*C)) The coil and capacitor types make very little difference to the range you will achieve.
2. The limitiation is how much power you can get from 4 AA-cells, it is quite small. If you assume 200mA max current, the power will be less than (4 * 1.5V) * 0.2A = 1.2W. Given typical power amplifier efficiency, a figure of about 0.75W is more likely.
3. Not really, if you built it exactly as in the diagram with the coils lined up with each other and nothing between them, you would be lucky to get 10% of the transmitted power transferred to the receiving circuit. However, where you diagram has the letter 'B' you would have a metal screen and 4m of high loss soil, almost all the signal would be lost. Maybe 0.000001% (my guess) of the signal might be received on the surface so you would need a very sensitive and selective receiver circuit to pick it up.
The example of PIGs you have shown elsewhere are designed to fit in small diameter pipes (~40mm) which would have thin walls and the sensors clamp directly to the outside of the pipe wall. The situation of thicker walls and much greater distance to the sensor make the problem much harder and other location methods more feasible.
Brian.
thanks Brian.Please don't keep opening new threads on the same topic.
1. The coils and capacitors have to make the coils resonant at 22Hz. Use the formula: 22 = 1/(2*Pi * Sqrt(L*C)) The coil and capacitor types make very little difference to the range you will achieve.
2. The limitiation is how much power you can get from 4 AA-cells, it is quite small. If you assume 200mA max current, the power will be less than (4 * 1.5V) * 0.2A = 1.2W. Given typical power amplifier efficiency, a figure of about 0.75W is more likely.
3. Not really, if you built it exactly as in the diagram with the coils lined up with each other and nothing between them, you would be lucky to get 10% of the transmitted power transferred to the receiving circuit. However, where you diagram has the letter 'B' you would have a metal screen and 4m of high loss soil, almost all the signal would be lost. Maybe 0.000001% (my guess) of the signal might be received on the surface so you would need a very sensitive and selective receiver circuit to pick it up.
The example of PIGs you have shown elsewhere are designed to fit in small diameter pipes (~40mm) which would have thin walls and the sensors clamp directly to the outside of the pipe wall. The situation of thicker walls and much greater distance to the sensor make the problem much harder and other location methods more feasible.
Brian.
I would suggest an experiment to see if it is feasible.
You can get enough power out of a single NE555 timer IC. Wire it as an astable oscillator with a 3.3uF timing capacitor, top resistor of 3.3K and bottom resistor of 8.2K, this will make it oscillate at about 22.2Hz while using standard component values. That is near enough for the experiment. Wire a 1,000uF capacitor across it's supply pins to keep the impedance low.
From its output pin, wire a 33 Ohm resistor to limit the output current then wire the transmitting coil and capacitor to the 6V supply. If you use a 10uF non-polarized capacitor and 5.25H coil in parallel it should resonate. If you wind the coil with an air core, 50mm tube diameter and space it to be 50mm length, you need 12,437 turns, that's lots of wire! You can decrease the number of turns by using a higher permeability core but you would have to find one the right shape and use the 'u' given by it's manufacturer.
That will give you a fairly compact transmitter producing EM waves at 22Hz. Next you need the receiver.
In a real tracer you would have to make the receiver coil highly directional but for the experiment you can make an identical one to the transmitter and use the same capacitor value across it. If you wire it as in your diagram and use a voltmeter as the load, you should be able to pick up a small voltage when the coils are close to each other. Now the fun starts! place the transmitter inside a metal box and see if you can still pick up a voltage on the receiving coil outside it. I suspect it will drop to almost zero with maybe a tiny residual reading. You have to amplify the received signal by maybe 100,000 times (100dB gain) to bring it back to a usable level. To do that you will have to use several stages of amplification and to eliminate other sources of signal you will have to filter the signal with a narrow passband 22Hz filter.
If it works so far, the next step would be to see if it can also penetrate 4m of ground. Unless you have a mechanical digger and space for a crater, that would be difficult! You can get an approximation of signal strength by working horizontally, bury the transmitter in the metal box to a depth of say 0.5m then see if the receiver can pick it up from another 0.5m hole spaced 4m away. you will have to back-fill the holes to eliminate other signal paths that might be present in the horizontal test but not if it was used deep into the ground.
Brian.
Hi,
spacecrafts:
ISS is only 0.0004 million km away. (400km, you can go the distance by bike within a few days)
The Moon is 0.4 milion km away, and it is a long time ago..
The Mars is about 250 million km away. I doubt they use omnidirectional transmitting antenna. I rather think they use a narrow beam. And the receiving antennas are huge, no handheld types.
Klaus
There is a free running, Zero Volts switching, simple oscillator called Royer Oscillator. You only need a DC voltage.
Here is the circuit. I simulated it with a coupling coefficient of 0.0001 which is a wild guess ... I believe at 5 m distance and through a steel wall it will be much less.
When tuned at the same frequency the secondary side, higher voltage is achieved and distance is increased.
Here is the voltage accros the secondary side with and without tunning capacitor.
WITHOUT
WITH
I have picked values without thinking on the practical implementation, only to get 22 Hz. Maybe those high inductor/capacitor values are not practical for your approach.
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