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  1. _maxim_

    Alternatives to creeping contacts for high frequencies

    Thank you Tom, I need some time to read the documentation and to start with some trials.
  2. _maxim_

    Alternatives to creeping contacts for high frequencies

    Dear Baluncore The diagram in post #26 is a very basic thank circuit. If the coil L does not move in the magnetic field (with its sample inside), only one thank RF circuit is required. If the coil L moves from one position to another experiencing a different magnetic field, as in my case, a...
  3. _maxim_

    Alternatives to creeping contacts for high frequencies

    I want to thank you for giving me the opportunity to clarify some aspects: Never talked about horizontal movements. I talked ONLY about movement along the magnet axis, which is VERTICAL. ??? The coil (or resonator) is a part of the probe, it is inside the probe. By probe we mean the device in...
  4. _maxim_

    Alternatives to creeping contacts for high frequencies

    I did not refuse the idea of using sliding contacts, simply I have no idea on how to implement that on my project... Can you share with me some papers about sliding contacts? Think that the coil/resonator will move by at least 50-80 cm from one side to the opposite side in the magnetic field...
  5. _maxim_

    Alternatives to creeping contacts for high frequencies

    Every frequency at which the RLC circuit resonate (coil/resonator + selected tank filter Ct+Cm) is interesting to detect. Obviously it is unthinkable to read them all, I would just read only 4 or 5, from the highest (700-800 MHz) to the lowest (1-30 MHz), stepped.
  6. _maxim_

    Alternatives to creeping contacts for high frequencies

    Thank you for your comments but for the purposes of defining the problem it makes no sense to describe all the devices involved in the project. To make this discussion productive, it is sufficient to focus on the type of problem posed: how to make an efficient electrical connection given the...
  7. _maxim_

    Alternatives to creeping contacts for high frequencies

    18 MHz is an intermediate frequency which is used for subsequent elaboration of signal. The response picked up by the coil is the same of the frequency transmitter (that's why resonance). I see Thank you again, Tom!
  8. _maxim_

    Alternatives to creeping contacts for high frequencies

    Thank you Tom. About the Analog Switches, I think the main problem arises from the frequency: can 850 MHz @ tens of watts be handled ? Frequencies and powers delivered are in the range of radio/antenna applications... T/R switches are interesting... I will have a look around. Do you mean can I...
  9. _maxim_

    Alternatives to creeping contacts for high frequencies

    I just need a way to connect the coil to several RLC circuits which resonate at different residencies.
  10. _maxim_

    Alternatives to creeping contacts for high frequencies

    No no.. As I wrote, the schematic and the receiving stage is something like what I have, it is a very simplified version of my instrument. But the principle is the same.
  11. _maxim_

    Alternatives to creeping contacts for high frequencies

    The receiver is something like the following: http://www.conspiracyoflight.com/NMR/NMR.html
  12. _maxim_

    Alternatives to creeping contacts for high frequencies

    It looks like I can only use capacitors, as in the following general circuit Either the Matching Capacitor and the Tuning Capacitor are elements which I must select depending on the Frequency range. The L is the coil which moves in the magnetic field which must be connected with different Cm/Ct...
  13. _maxim_

    Alternatives to creeping contacts for high frequencies

    No, it can not be realized in such way: coils as in transformers generate magnetic fields which interact with the static field to be measured. The coil must be connected electrically with the RF circuits.
  14. _maxim_

    Alternatives to creeping contacts for high frequencies

    Ah ah sorry you're right.... Just corrected, my keyboard has been faster than my mind. Hope nobody considered offensive the mistyped
  15. _maxim_

    Alternatives to creeping contacts for high frequencies

    I anticipate immediately that I am not sure if this is the right place to ask my question, in case I had made a mistake I would migrate willingly into the relevant area. I have an RF circuit on small PCB board (about 3x2 cm) that moves along a vertical axis in a measuring probe (it serves...
  16. _maxim_

    Making a system with mobile electrical contacts

    Thank you for your suggestion, but unfortunately the signal captured by the coil is really sensitive to any RF noise and the resonant frequency is in the range of 600 MHz to 10 MHz (depending from the position), so I guess the only hope to get it out from the probe is by a solid RF connection.
  17. _maxim_

    Making a system with mobile electrical contacts

    Thank you for your questions, I will try to be as more detailed as possible. More details on microcoil here https://en.m.wikipedia.org/wiki/Microcoil The application is for a long-term use, it is a device for reading RF signals from a chemical liquid sample moved into a magnetic field at fixed...
  18. _maxim_

    Making a system with mobile electrical contacts

    This is a view of the chip supporting the coil, dimensions about 30 x 20 mm. This is the rear view of the CHIP where a Hall sensor is also visible The rectalgular boxes in both sides are for making the solenoid coil in contact with differernt RF circuit filters. Is it enough for explaning the...
  19. _maxim_

    Moving a solenoid coil in a strong magnetic field

    There is also a good piezo motor from Noliac that I am studying now. The question is a mechanical requisite: I do not know the way to avoid loading the piezo motor three too much, since the PAD 7433 is designed for low force systems. I will address this to mechanical engineer area. Thanks for...
  20. _maxim_

    Making a system with mobile electrical contacts

    Yes, sure : this i a thread of mine too :-) There I have found a lot of interesting ideas to move mechanically the PCB, now I am point the attention particularly to the electric contact aspect when it moves along the axis. Maxim
  21. _maxim_

    Making a system with mobile electrical contacts

    You're perfectly right and I am sorry for not having provided more details to my request. Please, let me find a way to sit down in front of my PC and I will try to draw a picture describing the needs.
  22. _maxim_

    Making a system with mobile electrical contacts

    Hi all, want to realize a system for a PCB which holds a solenoid coil moving in a vertical axis long about 600 mm. The coil must get electric contact only in some predefined positions so that, for a given quote, the coil connects to a different LC circuit for having different resonant frequency...
  23. _maxim_

    Moving a solenoid coil in a strong magnetic field

    I am in contact with a local supplier for a piezoelectric linear positioner U-523 form PI Physic Instruments. The main issue I see is the reduced distance covered - few centimeters - while 30-50 cm are needed. I have no idea how to increase that distance.....
  24. _maxim_

    Moving a solenoid coil in a strong magnetic field

    Interesting ... but we have to consider that everything should fit in few centimeters of space, about 50 mm to be more specific. The maximum vertical distance between the extreme points is in the range ofrom 30-50 cm or so.
  25. _maxim_

    Moving a solenoid coil in a strong magnetic field

    Thank you for having shared your experience. In NMR, currents in solenoids are in the range of uA o hundreds of uA so the resulting force against the main magnetic field is negligible. Also, the coil will be moved in steps, not continuously, and for any position a different RLC should be...
  26. _maxim_

    Moving a solenoid coil in a strong magnetic field

    Hi guys, a solenoid coil 10x4 mm needs to be moved along the vertical axis of a strong magnetic field (up to 14 Tesla) generated by a superconducting magnet. The coil must be contained into a classical probe for NMR spectroscopy, and moved vertically inside that probe. The main issue I am facing...
  27. _maxim_

    A Best coil design for homogeneus NMR RF pulse on liquid discs

    I see you point. Thank you anyway for devoting time to this discussion. Max
  28. _maxim_

    A Best coil design for homogeneus NMR RF pulse on liquid discs

    Ideally, I would like to acquire a T2 spectra in rather different fields respect to the main; for example, in the case of a magnet operating at 14.1 T (600 MHz 1H Larmor Frequency), 500-400-300-200-100-50-25 MHz might be interesting values. More generally, each value is acceptable to perform a...
  29. _maxim_

    A Best coil design for homogeneus NMR RF pulse on liquid discs

    I came up with an idea: I could create a single chip containing the sample and the coil. The liquid sample is collected in a suitable container (eg glass or other non-protonated material), closed, cylindrical and completely filled with the sample; the coil is a simple solenoid wrapped around...
  30. _maxim_

    A Best coil design for homogeneus NMR RF pulse on liquid discs

    Ok: let say that the sample shape could be changed in order to obtain the best homogeneity reachable in a non-homogeneous field. Has it to be spherical? Cylindrical? I can try to manage this requirement. From this assumption, it arises the coil geometry. The point is that we must measure T2's...
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