Challenge: Fastest Oscillator

Discussion in 'General Electronics Chat' started by tom66, Aug 24, 2010.

  1. tom66

    Thread Starter Senior Member

    May 9, 2009
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    OK, since it seems that no-one is submitting anything, I have made a big change to the rules.

    The new goal of this project is to develop the fastest oscillator you can in the most creative and inventive way you can.

    What counts as creative and inventive? One example I came up with was hijacking the PLL in a CPU from a computer (e.g. a Pentium 4) to generate a ~3 GHz clock signal. For this example, just showing the theory and wiring diagram would be enough to win you super geek cred.

    What doesn't count? Using a 20 GHz transistor as... well... a 20 GHz oscillator. Using components for their actual purpose is not creative and inventive. It can work, but it won't win.

    Closing date Sep 30th. I will judge not only on the highest frequency, but the most creative and inventive way to reach that frequency.

    ------ OLD POST BELOW ------

    Here is an idea for a forum project.

    The goal is to make the fastest oscillator using commodity parts.

    The parts you are allowed:

    • Any 74xx/40xx chip without an on-chip an oscillator.
    • All passive components: resistors, capacitors, inductors and so on.
    • Active components: transistors, diodes.
    • 555 timer including CMOS variants.
    You are not allowed: dedicated TTL oscillator cans, dedicated oscillator chips, PLL chips and anything a standard hobbyist wouldn't be able to acquire. Circuits can be built point-to-point if necessary for high frequency stuff.

    Each time we must reach a higher goal.

    The output need not be a square wave. It can be a sine wave or any kind of repeating cycle.

    I'll start with my submission of ~39 MHz from a 74LSxx: http://forum.allaboutcircuits.com/showthread.php?t=42096

    Next person has to submit a circuit which can go faster than 39 MHz. To prove the circuit is working please show a simulation or a scope trace.
     
    Last edited: Aug 29, 2010
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The circuit you made in the other thread is a propagation delay oacillator.
    It is descibed in the attached PDF (there it is with CMOS).
    With faster types of gates like 74FXX or 74SXX the oscillator will be much faster.

    Bertus
     
  3. someonesdad

    Senior Member

    Jul 7, 2009
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    Great idea. I'd suggest also including a statement that it must be at least a 1 volt fundamental as shown by a scope trace and it must be from an actual electrical circuit the submitter constructed and designed to be an oscillator. Otherwise, I'd just go get a 7400 and use my propane torch to heat the copper legs to incandescence and declare my entry was oscillating at 600 THz and all around that neighborhood. :p

    You might also want to rule out microwave/stripline stuff -- otherwise a microwave weenie will submit a multi-GHz oscillator none of us mortals could beat.

    Oh, and no connecting a scope probe to your cell phone's antenna...

    On second thought, I predict that folks will come up with clever ways to get around your rules -- and these may be more entertaining than the original goal. :rolleyes:
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I made a 10 Ghz oscillator using a gunn diode in a waveguide ( more that 30 years ago).
    I made a pair of them to communicate with eachother.
    There was also a recieving diode in each of them.

    Bertus
     
  5. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    How about a simple UV emitting diode, approximately 7.5X10E14 Hz? All you need is a battery and resistor.

    John
     
  6. tom66

    Thread Starter Senior Member

    May 9, 2009
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    I highly doubt a Gunn diode is in a standard hobbyist's toolbox. I would therefore exclude any device with negative resistance characteristics. Also you are excluded from any frequency >10GHz. And no magnetrons for the 2.4GHz band. All of the circuitry to produce the oscillations, except for the power supply, must be contained in the circuit you build, you cannot attach a scope probe to any emitter, or use a function generator.

    I have just got 69-72 MHz(!) out of a 74LS00 quad NAND, by tweaking some wiring. The frequency is somewhat unstable, varying from 69 MHz all the way up to 72 MHz. It's only at around 40mVp-p and it is a bit noisy, but it is a massive 69 MHz!! How the hell does it do that?
     
  7. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    As a ham amateur a gunn-diode was easy to get.
    The radio-market had them.
    I made the waveguide (back then) at school.
    The drawings for it came out of the RSGB VHF-UHF manual.

    [​IMG]

    Bertus
     
  8. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Ah, no fair changing the rules. The International Union on Electronic Competitions will certainly hear about this! Now, before I invest oodles of time, what do you consider "the" frequency? Do higher harmonics count? What is the frequency of a really good square wave?

    John
     
  9. tom66

    Thread Starter Senior Member

    May 9, 2009
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    At whatever frequency you can justify. :p If the waveform is oscillating between three levels, say, half on, off, full on, off, half on and so on consider the frequency as the 1/delta between each pulse. As a microcontroller or comparator would interpret it.

    I just realised I could clock my microcontrollers off this oscillator. Maybe the STM32 72MHz ARM processors would work on it. A bit low output though. One cool thing to do would be to make the frequency adjustable, then I can overclock some processors. :D
     
  10. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I'll drop a hint - look into the 74ACT / 74BCT series

    Get ready to get creamed with your puny 39 MHz.
     
  11. massive

    Member

    May 7, 2010
    20
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    Bertus made a what what ?
    Ive never seen or heard of one. Thats old school.
    Ive had a look and only a look , at magnetrons and they look scary.
    Im guessing something something GUNNS add instant sun tan .
    (any plans stashed away ?)
     
  12. marshallf3

    Well-Known Member

    Jul 26, 2010
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    A Gunn diode is commonly used as the local oscillator in a radar detector.
     
  13. retched

    AAC Fanatic!

    Dec 5, 2009
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    It may be interesting to see who can actually hit a mark.

    Say...123mhz. In real life, when you need an osc, it is of a certain frequency.

    SO, if you were on a stranded island, blah blah blah, and your whoo-ja-bob's crystal was broken, how would you get it to work with only the parts stated in the rules.

    That would be interesting.

    HOWEVER, you are the creator of this competition... So however you want to get beat is up to you ;)
     
  14. tom66

    Thread Starter Senior Member

    May 9, 2009
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    I just did this as a bit of fun. So far, nobody has beat my 69 MHz. Come on, guys! I'm able to get 78 MHz now.

    That desert island thing sounds interesting. But I shouldn't change the rules. It's a challenge to go faster. I want to see how fast a hobbyist can get an oscillator working. So no Gunn diodes!
     
  15. SgtWookie

    Expert

    Jul 17, 2007
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    I'll also vote for a minimum 1V P-P output signal. Even that is not valid for TTL logic levels, but having people submit arbitrarily low P-P levels could get ridiculous.

    Additionally, I'd vote for the exclusion of people who had >= 6 months training and/or >= 6 months OJT (on the job training) in electronics.
     
  16. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Leaves me out, of course I don't have the time to mess with it anyway. The 74ACTxx series has propagation delay times in the single nS range, I used them to make a photon counter for the physics department one time.

    I'm starting to get some hints I should spend more time actually in the office than at home so I better start humoring them, besides that several of my projects that are done or in progress belong up there anyway.
     
  17. tom66

    Thread Starter Senior Member

    May 9, 2009
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    1Vp-p... that excludes my entry, it only has a 40mVp-p swing. I just am curious how fast an oscillator can be built using standard parts. Bonus points awarded arbitrarily if you can get a 1Vp-p output.

    I was thinking of building a TTL open-collector inverter, and chaining three in a loop to get high frequencies. If I used a 2N2222, I could probably get up to 100-150 MHz.
     
  18. retched

    AAC Fanatic!

    Dec 5, 2009
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    Is this going to be an endless competition or is there a due date?
     
  19. tom66

    Thread Starter Senior Member

    May 9, 2009
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    No due date. But as soon as possible, I want to see people's ideas! Each oscillator needs to be faster than the previous oscillator.
     
  20. PackratKing

    Well-Known Member

    Jul 13, 2008
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    Is a colpitts-type osc. legal, or is there a limit to what they can produce anyway.?
     
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