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Discussion in 'Electronic Design' started by M. Hamed, Jul 16, 2013.

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  1. Fred Abse

    Fred Abse Guest

    What frequency. What multimeter? You're lucky if you have a meter that
    covers more than a few kHz.

    My (expensive) Fluke 87V only goes to 20kHz on *some* ranges. On others
    it's 5kHz.

    My even more expensive HP bench multimeters likewise.
     
  2. M. Hamed

    M. Hamed Guest

    Yes. It was a dumb thing to expect :) What was I thinking?!!
     
  3. Fred Abse

    Fred Abse Guest

    Americans, Brits, and (I believe) Australians, Germans, and Frenchmen
    honor designers by naming their designs after them. Even your idols, the
    Soviets did.

    I'm sure I could name some Nederlanders, too, given time.
     
  4. M. Hamed

    M. Hamed Guest

    Ok, now it's starting to sink in! Thanks.
     
  5. Fred Abse

    Fred Abse Guest

    Yes, I see them. Tell me more.
     
  6. John S

    John S Guest

    It is frequently convenient to refer to standard circuits by name to
    assist communication between discussers ;-)
     
  7. John S

    John S Guest

    The Hartley can be constructed using two inductors rather than one that
    is tapped. In my opinion, that makes it sort of a Colpitts anyway. I
    don't like tapped inductors because it is harder to change for
    experiments. YMMV.

    While I'm thinking about it, I had some problems getting a Colpitts to
    start and run properly. I learned that my ceramic caps had high (for
    ceramic) dissipation factors (low Q). Replacing them with NP0 cured the
    problem. You may not run in to this problem, but it might be worthwhile
    to remember.

    You're doing great. Keep up the good work.

    Cheers,
    JohnS
     
  8. John S

    John S Guest

    Yow! I just looked at your LTSpice thing. Your simulation is actually
    using 4 inductors, not 2. The reason is that you do not provide coupling
    between the tapped parts.

    Just FYI.

    JohnS
     
  9. Glenn

    Glenn Guest

    ....

    Jan - then you do not know the Vacker oscillator either ;-)

    E.g. Why do engines have names V8, Stirling Engine, Jet Engine and so on.

    -

    My presumption is that all variable LC oscillators ought to be using
    Vacker design to correctly maintain oscillation combined with low
    feedback and amplitude - over a small - or especially wide frequency
    variation.

    With all the electronic made in the last 30 years, why has no one found
    this design (again)? Why has no one been educated about this oscillator?


    The Vackar VFO oscillator:
    http://www.qsl.net/va3diw/vackar.html
    Quote: "...
    Jiri Vackar [Jiří Vackář] invented his VFO oscillator during late 40s.
    It is probably the most stable VFO oscillator known. Thanks George!
    ....
    The frequency tuning range is above 2.5, not observable in any other
    type of oscillator. The Coupling ratio is fixed; typical range is 1:4 up
    to 1:9.
    []
    The tuning is provided independently of coupling. Transistor's
    parametric variables are isolated from the resonator. The transistor
    input is not overloaded as Clapp or other circuits.
    ....
    The stability is close to XO.
    ....
    Ordinary oscillator has poor tuning range, the output voltage swing is
    unstable, and the frequency stability is poor as well. The industry
    tries hard to make its sale pitch, to replace single oscillator with 50
    ICs, digital dividers, approximation registers, thermostats, and other
    junk. Now what?
    ....
    The best regulator of all times is maybe the LM723. [really :)]
    ....
    The VFO is better solution than the AD9850,AD9891 DDS - direct digital
    synthesizer chip.
    ....
    Do you want to spend time calling around and dealing with ten weeks lead
    time? An old cap from an old TV tuner can help to solve your problem.
    The treasures are around you.
    ...."

    Scanning of original paper:
    http://web.archive.org/web/20120219062848/n1ekv.org/Oscillators/Vackar_wholepaper.pdf
    http://n1ekv.org/Oscillators/Vackar_wholepaper.pdf

    http://n1ekv.org/Oscillators/2003 MUD resources.htm

    -

    A regenerative receiver ought to be easier to tune with Vacker design.
    Why has anyone not thought of that - assuming no one did - please
    correct me if I am wrong.

    Glenn
     
  10. Glenn

    Glenn Guest

    On 20/07/13 22.10, Jan Panteltje wrote:
    ....
    White Hockey puck oscillators...
     
  11. Guest

    Named after their inventor Dr White-Hockey? ;)
     
  12. Glenn

    Glenn Guest

    http://en.wikipedia.org/wiki/Vackář_oscillator
    Quote: "...
    Specifically, Vackář found that forward transconductance varied as ω3
    for the Clapp oscillator, as 1/ω for the Seiler oscillator, and as ω/Q
    for his design, where the Q factor of the coil (L1) increases with ω.
    ...."

    /Glenn
     
  13. Glenn

    Glenn Guest

    These YIG-stones is also smart - great oscillator and filter balls - but
    not named after any human? They are also EM coupled:
    http://en.wikipedia.org/wiki/Yttrium_iron_garnet
    http://en.wikipedia.org/wiki/YIG_sphere

    Used in elder quality spectrum analyzers.
     
  14. josephkk

    josephkk Guest

    Wouldn't surprise me. Most of the High K ceramic dielectrics are
    piezoelectric in nature. They also make physically resonant filters with
    the same materials.

    ?-)
     
  15. Glenn

    Glenn Guest

    On 21/07/13 10.39, Jan Panteltje wrote:
    ....
    The reason is high ESR. Even ce-capacitors are divided in "normal"-ESR
    and low-ESR.

    http://en.wikipedia.org/wiki/Equivalent_series_resistance

    In window "Applications" you can choose SMPS filtering:
    http://www.digikey.com/product-search/en/capacitors/ceramic-capacitors/131083

    Capacitor Values:
    Don’t Believe the Label:
    http://powerelectronics.com/site-fi...ackaging_interconnects/packaging/705PET21.pdf

    Therefore some ceramic types can be used for measuring voltage or
    temperature, because the capacitance vary.
     
  16. Fred Abse

    Fred Abse Guest

    Shouldn't that be "Vackar"?
     
  17. M. Hamed

    M. Hamed Guest

    Yes. That was done on purpose. I remembered reading somewhere that coupling is not needed (I think it was in Hayward's Introduction to RF Design).
    It was something I wanted to try and it saves me an extra toroid. Wounding both inductors on the same toroid would have been essentially the same.
    Thanks John. I appreciate the encouragement.
     
  18. M. Hamed

    M. Hamed Guest

    From my readings, capacitor low Q is usually not an issue up to high frequencies. Before that the inductor Q is more important. I am compelled to ask at which frequencies was this a problem to you?
     
  19. M. Hamed

    M. Hamed Guest

    The discussion about capacitors reminded me of a good article I read a few weeks back on EDN:

    http://bit.ly/12cukvF

    It has mention of piezoelectric effects and also variations with voltage which are often not specified.
     
  20. Glenn

    Glenn Guest

    Some pesky ceramics are superconductors:
    https://en.wikipedia.org/wiki/YBCO
     
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