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Frequency meter for prop — Parallax Forums

Frequency meter for prop

CenlasoftCenlasoft Posts: 265
edited 2009-11-30 08:43 in Propeller 1
I have been playing with coils and LC circuits with the prop. I need a simple (discrete parts ?555 timer) frequency meter to measure frequencies between 30hz and 1 khz. I have looked on the web, but have not found anything. I would appreciate any samples or suggestions. I am working with low frequencies on metal objects. My instrument is based on the Prop. I just need a meter to sense low frequencies using an LC circuit to monitor AC. I was thinking of using a tunable parallel LC circuit and 555 timer, but I am stuck.
Thanks,
Curtis

Comments

  • LeonLeon Posts: 7,620
    edited 2009-11-30 02:46
    Use the sound card? There should be some FFT software for it that you could use.

    Leon

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Amateur radio callsign: G1HSM
  • Bob Lawrence (VE1RLL)Bob Lawrence (VE1RLL) Posts: 1,720
    edited 2009-11-30 03:21
    @Cenlasoft

    Do you have access to a multimeter? many of them have a freq option.

    Or:

    The counter makes use of 5 cascaded CD40110 which combine a decade counter, a display latch and a 7 segment LED driver in a single chip. (The decimal points are driven by IC8x.) The counter allows up and down counting (although only up counting is used in the frequency counter) and counts on the rising edge. An over- and underflow indicator is provided via CD4044 which is fed back to the logic board to allow automatic adaption of the divider or gate time if the counter has an overflow.

    www.triplespark.net/elec/analysis/FreqCnt/counter.html

    Post Edited (Bob Lawrence (VE1RLL)) : 11/30/2009 3:33:26 AM GMT
  • kwinnkwinn Posts: 8,697
    edited 2009-11-30 03:47
    Take a look at these chips. Add 1 second gate, digit driver, and leds for a 4 digit frequency counter.

    Scratch that. Obsolete

    Post Edited (kwinn) : 11/30/2009 3:57:55 AM GMT
  • kwinnkwinn Posts: 8,697
    edited 2009-11-30 04:15
    You could always use the prop counters on your instrument, or another prop. Counter, timebase, display drivers all in one chip.

    If you want a discrete solution try the mc14553 3 digit BCD counter. Needs a few extra parts to work.
  • DroneDrone Posts: 433
    edited 2009-11-30 08:43
    Just use a separate cog as a frequency counter. There's a counter object in ObEx here:

    obex.parallax.com/objects/479/

    Use the Propeller Serial Terminal or a serial LCD to read-out the frequency.

    Rgds, David
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