Can this frequency counter measure lower frequencies

Discussion in 'General Electronics Chat' started by circuitfreak2000, Apr 10, 2015.

  1. circuitfreak2000

    Thread Starter Member

    Apr 7, 2015
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    I was thinking about getting this frequency counter
    [​IMG]

    But now that I looked closer and thought about it I see a problem with this one. Apparently it can only measure 50Mhz + and I plan to build some RF circuits using crystals, some below 30 Mhz.

    Can this device pick up the frequency or will it only start working at 50Mhz or above? If it can't, that would be a bummer.
     
  2. DickCappels

    Moderator

    Aug 21, 2008
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    Probably not reliably. There are counters and prescalers that cannot operate below a specified frequency because of their design.
     
  3. circuitfreak2000

    Thread Starter Member

    Apr 7, 2015
    39
    1
    So if the frequency is below 50Mhz, this device will not show anything at all, maybe just "No Signal" ?
     
  4. DickCappels

    Moderator

    Aug 21, 2008
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    Well, not exactly 50 MHz. I have a frequency meter that uses a 1.1 GHz prescaler that is rated for operation between 100 MHz and 1.1 GHz. When I try to drive it at frequencies much below 100 MHz (about 80 Mhz from memory) I get random counts.

    If the frequency meter in your post could reliably work below 50 MHz, wouldn't the maker want to advertise that fact?
     
  5. circuitfreak2000

    Thread Starter Member

    Apr 7, 2015
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    You are right. I just had a glimpse of hope that it would show some results even if not 100% accurate.
     
  6. ScottWang

    Moderator

    Aug 23, 2012
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    If your input signal through a 5 times multiplier then you can measuring down to 10 MHz.
     
  7. circuitfreak2000

    Thread Starter Member

    Apr 7, 2015
    39
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    That's a very interesting idea! How would you go about multiplying the output signal?
     
  8. circuitfreak2000

    Thread Starter Member

    Apr 7, 2015
    39
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    For about twice the price I found this frequency counter that works from 1Mhz +.

    [​IMG]

    Specification :

    Response time : 0.2s
    Auto power off time : 80s
    Frequency range : 1Mhz---2400Mhz
    RF power range : 0.1W---50W
    Current consumption : About 100mA
    Impedance input : 50Ohm accuracy : +/- 10% when the frequency is 140Mhz~170Mhz,400Mhz~470Mhz
    Working tempreture : 0~40°
    Battery : 1.5V(AAA) x 3

    Do you guys think this one can detect the frequency of RF crystal transmitter reliably? It also shows the signal power which is great. I looks a heck more pro than the other one.
     
  9. DickCappels

    Moderator

    Aug 21, 2008
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  10. circuitfreak2000

    Thread Starter Member

    Apr 7, 2015
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    You can compare the RF circuits that I want to create to ones for RC cars and things like that. I believe they generate a pretty strong signal since they work over meters away. Would it be enough for the 1 Mhz + Frequency counter I showed above to pick up?
     
  11. ScottWang

    Moderator

    Aug 23, 2012
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    My original is using some other logic parts, but it seems not going to work, then I thought that i saw the chip from TI about two years ago , you may check this MuxIt™ PLL FREQUENCY MULTIPLIER.
    - Input Clock Frequencies From 5 to 50 MHz.
    - Multiplied Clock Frequencies up to 400 MHz.
     
  12. ian field

    Distinguished Member

    Oct 27, 2012
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    Probably with a PLL and a frequency divider, the PLL contains a VCO which you divide down to similar to the frequency you want to measure. The phase comparator locks and feeds pulses to a LPF, whose output voltage controls the VCO.

    The VCO is of course running at divider times the measurement frequency - so you use the high range counter to measure that.
     
  13. circuitfreak2000

    Thread Starter Member

    Apr 7, 2015
    39
    1
    Thank you for all the comments guys. I think in the end it's just better to dish out the extra $15 bucks and get a decent frequency counter that works from 1 MHz +. :rolleyes: This is the one I chose. Looks like a beaut.

    [​IMG]
     
  14. flat5

    Active Member

    Nov 13, 2008
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    No. I have the Gooit.
     
  15. ScottWang

    Moderator

    Aug 23, 2012
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    The price of GY561 comparing to the GY560 is over triple, Just for that 1M~50Mhz band, the price is so difference and more expensive?
     
  16. DickCappels

    Moderator

    Aug 21, 2008
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    Most likely (IMO) the high frequency version uses inexpensive parts that are mass produced for telecommunications that don't usually go VHF, but the low frequency version use smaller building blocks possibly like the 74HC series, etc. resulting in the need to use more parts.
     
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