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$7 Frequency Counter Kit 50MHz — Parallax Forums

$7 Frequency Counter Kit 50MHz

ercoerco Posts: 20,256
edited 2015-09-01 03:39 in General Discussion
Just do it. A companion to the $20 digital oscilloscope kit we all got.

http://www.ebay.com/itm/Digital-LED-DIY-Sets-1Hz-50MHz-Crystal-Oscillator-Frequency-Counter-Meter-Kits-/231668525889

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Comments

  • localrogerlocalroger Posts: 3,451
    Done!
  • ercoerco Posts: 20,256
    Once again, LR is the first guy in the pool! Dare I mention that Electronic Goldmine has their $5 "Mystery Box of ICs" for sale again? :)
  • Heater.Heater. Posts: 21,230
    Cool. Not enough digits but cool anyway.
  • User NameUser Name Posts: 1,451
    The 14¢ shipping is a budget buster. >:\
  • Heater.Heater. Posts: 21,230
    So can't we make this with a Prop and some digits. Good for 100Mhz with a suitable XTAL.
  • PublisonPublison Posts: 12,366
    edited 2015-09-01 15:47
    Heater. wrote: »
    So can't we make this with a Prop and some digits. Good for 100Mhz with a suitable XTAL.

    Prop $6.99
    XTAL $1.10
    (From Parallax QTY 1)
    Puts it over erco's budget. :)

    I have a couple of Hanno's products, Viewport and the PropScope. Shows what the Prop can do.

    Of course erco only wants to talk BS1 or BS2. :)


  • PublisonPublison Posts: 12,366
    The PropScope ships with a 6.25 XTAL (100Mhz)
  • RDL2004RDL2004 Posts: 2,554
    edited 2015-09-01 16:49
    50 MHz isn't all that great. If I was going to be limited, I think I'd drop to 10 MHz and buy a UT136B. For less than 2x the cost, you get a lot more functionality. It's actually a pretty decent DMM for the price and is fairly well regarded by the people on the EEVblog forum. Remember, you really need at least two multimeters.

    $16.80 shipped from the US, available from several others, and you can even get them from China if you want.

    www.ebay.com/itm/UNI-T-UT136B-Auto-Range-Digital-Multimeter-AC-DC-Frequency-Resistance-Tester-/381277496822

  • localrogerlocalroger Posts: 3,451
    That DMM is also only 4 digits. The kit looks like an good choice for a panel frequency display, which seems to be by intent since it can be set up to subtract several common IF frequencies.
  • jmgjmg Posts: 15,173
    Heater. wrote: »
    So can't we make this with a Prop and some digits. Good for 100Mhz with a suitable XTAL.

    Well, < 50MHz in Freq, and 10ns in dT

    Didn't someone mention a Badge with an OLED ?
    That could make a good FreqCtr engine ?
  • jmgjmg Posts: 15,173
    RDL2004 wrote: »
    50 MHz isn't all that great. If I was going to be limited, I think I'd drop to 10 MHz and buy a UT136B. For less than 2x the cost, you get a lot more functionality. It's actually a pretty decent DMM for the price and is fairly well regarded by the people on the EEVblog forum.

    Nice, but it says
    Frequency 10Hz/100Hz/1kHz/10kHz/100kHz/1MHz/10MHz ±(0.5%+3)
    I guess that 0.5% is some RC Osc cal, or maybe a cheap Ceramic Resonator.
    Limits the use somewhat ? - ok for ball-park stuff.
  • RDL2004RDL2004 Posts: 2,554
    Ah yes, ballpark, but look what else you get with it. Here's a review:

    https://youtube.com/watch?v=URKSs02qz5c

    So the 5 digit counter has special RF uses? Anyway, if more digits = better...

    ebay.com/sch/i.html?_nkw=frequency+counter+2.4+GHz+cymometer

  • jmgjmg Posts: 15,173
    RDL2004 wrote: »
    Anyway, if more digits = better...

    ebay.com/sch/i.html?_nkw=frequency+counter+2.4+GHz+cymometer

    Yup, more digits is better :)
    That's a pretty cool unit, as it also says:

    Using temperature-compensated voltage controlled crystal oscillator (2.5 ppm VC-TCXO).

    only minus, is they did not do a reciprocal counting engine...

    Based on Performance/price, that one could even trump the kit in #1.
  • RDL2004RDL2004 Posts: 2,554
    There's a little discussion about it here:

    eevblog.com/forum/projects/ten-dollar-pic-100khz-2-4ghz-frequency-counter/

    Looks to be pretty decent, lacking in documentation though. Appears hard to go wrong for the price, but by time you get everything else you need for a finished project, may be just as well to buy one of those <$100 Victor branded units.
  • jmgjmg Posts: 15,173
    edited 2015-09-01 23:05
    On the topic of More digits is better, I also came across this!!

    http://www.dx.com/p/jy-mcu-16x-digital-tube-yellow-led-module-104311#.VeYt1Pmqqko

    No freq ctr, but you could connect this to a Prop.
    Now, what to use all those digits for... :)

    Freq and Voltage ? Duty Cycle and period ? Dual Counter ?
    Baud value and Character counter ? Cycles and Frequency ?

    Oh, Module looks to be no longer available ? A digit too far ?
    The TM1640 LED driver seems still available ?
  • Heater.Heater. Posts: 21,230
    Wow, RDL2004, love that little frequency counter. Also in blue, great.

    Amazingly it's the first time I ever came across the word "cymometer".

  • RDL2004RDL2004 Posts: 2,554
    Somebody wrote on wikipedia that it was a word used to refer to frequency counters manufactured in China. Kind of like how they say "weld" instead of "solder" and 7 segment LED displays are "? bit digital tube displays", where ? is the number of digits. Whatever, it separates them out on ebay pretty well.

    It's hard to resist ordering one of the VFD versions.
  • Heater.Heater. Posts: 21,230
    edited 2015-09-02 06:34
    Fascinating. See schematic and picture of a real cymometer attached.

    The word "cymometer" does not seem to exist in the Oxford dictionary so it's not English :)

    But it is in Webster on line dictionary defined as "An instrument for exhibiting and measuring wave motion". Seems to date back to 1913.

    However the word was coined by the Englishman who invented the cymometer in 1904:

    J.A. Fleming (University College London), who supervised
    the Cornwall end of the famous transatlantic radio
    communications of Marconi, is reported to have said:
    “… The wavelength of the electric waves sent out from Poldhu
    Marconi station in 1901 was not measured because I did not
    invent my cymometer or wavemeter until October, 1904..” [4].
    Prior to this wavemeters had been developed (e.g. by Dönitz,
    German patent date 4th April 1903) and perhaps even
    marketed commercially in Germany (for example by
    Telefunken – then called Gesellschaft für drahtlose
    Telegraphie m.b.H., System Telefunken, founded 1903 in
    Berlin)


    Fascinating story here:
    http://blogs.mhs.ox.ac.uk/innovatingincombat/files/2013/03/ACDavies_wavemeters_Oxford_conference.pdf

    Lot's of nice pictures of cymometers or "wave meters" as they are normally known.


    cymometer.png
    593 x 369 - 151K
  • Heater.Heater. Posts: 21,230
    Also this paper from 1903:

    "The Application of the Cymometer to the Determination of the Coefficient of Coupling of Oscillation Transformers"
    J A Fleming
    Proceedings of the Physical Society of London, Volume 19, All articles

    http://iopscience.iop.org/article/10.1088/1478-7814/19/1/348/meta

    We have stumbled into some great history here.
  • RDL2004RDL2004 Posts: 2,554
    A very old word then, not used in a long time. It seems to be derived from the Greek word Kymo.

    kymo-, kym-
    (Greek: wave, sprout; swollen)

    Kind of makes you wonder how the Chinese found this word to describe their frequency counters.
  • Heater.Heater. Posts: 21,230
    May be the Chinese read the Proceedings of the Physical Society of London :)

    I might guess that the Chinese name for such a thing is descriptive of something that counts waves. And that a literal translation of that becomes "wave counter" hence they come to "Cymometer"

    Anybody here speak Chinese?

    Now get this: We refer to these things as "Frequency Counters". Which on reflection is totally wrong. They do not count the number of frequencies in a signal!


  • jmgjmg Posts: 15,173
    Heater. wrote: »
    Now get this: We refer to these things as "Frequency Counters". Which on reflection is totally wrong. They do not count the number of frequencies in a signal!

    No, but they do count cycles and give the answer in frequency.
    Many of course, can do both Frequency and Counts, so Frequency Counter is entirely correct for those.

  • RDL2004RDL2004 Posts: 2,554
    Maybe it's a combination/contraction of frequency meter and wave counter. I tend to agree though, frequencies are not being counted.
  • ercoerco Posts: 20,256
    edited 2015-09-02 17:08
    Great discussion all, I love all the insight. I may need that blue LED unit too. I would have killed for any type of frequency counter back in my ham radio Novice days circa 1974. My Heathkits' slide rule dials were only so readable. "Parallax error" and all. :)

    CQ CQ de WN4CIK K...

    Edit: Blue red or green all $11.88 from same seller. Collect them all! http://www.ebay.com/itm/Blue-0-1-60MHz-20MHz-2-4GHz-RF-Signal-Frequency-Counter-Cymometer-Tester-/181666154685
  • Heater.Heater. Posts: 21,230
    edited 2015-09-02 17:19
    Edit: Deleted as being badly conceived.
  • Heater.Heater. Posts: 21,230
    erco,

    73 OM

  • kwinnkwinn Posts: 8,697
    Heater. wrote: »
    ............

    Amazingly it's the first time I ever came across the word "cymometer".

    Me too. Had to google it. Wave cycle meter. Guess that makes it the mother of all frequency meters.

  • ercoerco Posts: 20,256
    edited 2015-09-02 21:34
    If you really want to kick it old school, pony up $27 for this new old stock frequency meter. Only 4 left!

    http://www.ebay.com/itm/JBT-Instruments-30-FHXX-Reed-Type-Frequency-Meter-New-Surplus-in-Original-Box-/371418683852?hash=item567a4759cc
  • localrogerlocalroger Posts: 3,451
    OK I also ordered one of the ones RDL2004 linked. Probably a better price for performance than the original kit but you don't get the satisfaction of putting it together and wondering why it doesn't work right :-)
  • ercoerco Posts: 20,256
    Me too. FYI, this seller takes best offers and accepted my bid of $11.13. :)

    http://www.ebay.com/itm/181666154685
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