tape deck output as clock for logic

Discussion in 'The Projects Forum' started by mxabeles, Jun 19, 2010.

  1. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    Hi there
    I would like to replace 555 timer clock with amp output of tape player to step through a 4017 chip. Here is my thinking right now, let me know if this is in the right direction:
    headphone out from tapedeck : 12vdc amplifier 7 watts (amperage would be 1.7A i belive)
    12vdc amplifier split to loudspeaker and 7805 regulator (with series resistor to drop current...not sure how this will be shared between loudspeaker and 7805 tho)
    output of 7805 to logic input......
    Hmmm this is my thinking so far. I'm not really sure of the switching speed of the 7805 and it probably isn't meant for this application. Maybe using an opamp as a switch?
    Thanks,
    M
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
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    Are you trying to play samples from the tape deck?

    Im kind of lost on what effect your trying to achieve.
     
  3. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    hey,,what I would like to do as of now is have the amplitude peaks from the tapedeck clocking a 4017 chip.
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Do you want to look at the real frequencies or the envelope of the signal?

    Bertus
     
  5. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    in the end I would like to be able to take several frequencies out of the sound and use each band on a different 4017 chip but for right now I am only concerned about using the overall amplitude.
    so when the output hits "x" voltage then a transistor or regulator or opamp (i dunno which) will switch from 0 to 5volts telling the 4017 to clock forward.
    Another aside, I would like to add an AND gate at the output of the 4017 w/ other input to amplitude out, so that way the led or speaker or whatever device is being powered by the 4017 will only be on when speaker is emitting sound.
     
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    You can make bandpass filters for the frequencies of interest.
    For the amplitude detection you can use enevelope detectors afther the filters with a comparator if a certain level is crossed to trigger the 4017.

    Bertus
     
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  7. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    Last edited: Jun 19, 2010
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The RC values for the envelope detector is dependend on how fast you want the signal to be followed.
    You could try a RC timing of 10 - 100 mSec.

    Yes,you can make a comparator with a single powered opamp.

    Bertus
     
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  9. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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  10. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The LM339 will work fine as a comparator.
    Keep in mind that the output is open collector.
    It needs a resistor from output to the powersupply.

    For the filters you can not use the 339, but a normal opamp.
    The LM324 or TL084 could do the job.

    I have attached an application note from TI on single powersupply circuits with opamps.
    Fig 17 and 18 will show filter designs.

    Bertus
     
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  11. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    word, thanks berts.
     
  12. SgtWookie

    Expert

    Jul 17, 2007
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    I think you'll find that the LM324 is a bit slow for the higher audio frequencies.

    A TL08x (TL081 single, TL082 dual, TL084 quad) would work OK though - so would LF353 dual opamps
     
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  13. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Seems that if this is the ultimate goal, he might as well start with frequency discrimination...with an LM567.

    Ken
     
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  14. retched

    AAC Fanatic!

    Dec 5, 2009
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    Thats the problem with electronics these days. All the discrimination. ;)

    However true, choosing which frequency you wanted to measure, or as your trigger frequency would be key.

    You can even use frequencies that humans cant hear to encode changes or actions regardless of the music.
    Especially if you wanted a tape controlled light show during the silence leading up to the start of the sound clip.

    Remember film strips in elementary school? When you heard the 'BEEP' you advanced 1 frame?

    Then a few years later they had the tape deck connected to the projector, and it advanced automatically with no audible 'BEEP'. You could do the same. just use the trigger for whatever action you want to perform.

    The LM567C is capable of .01hz to 500khz, so WAY beyond our hearing capacity.

    Here is the info on it:
    http://www.national.com/mpf/LM/LM567C.html#Overview

    It is set up to provide a saturated transistor switch to ground when the frequency it is "listening" for is heard.

    Good find KMoffett.
     
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  15. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    I fail to understand the need to simply count the number of times a frequency or band of frequencies exceeds a trigger point. It's not like he's making a graphic display of dancing led's for the discriminated bands.
     
  16. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    thanks everyone!
     
  17. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    and wow about using "silent" high frequency tones to trigger logic is blowing my mind apart!
    So correct me if I'm wrong but I could "easily" do this:
    have 4 channel audio track
    each channel is linked to a corresponding high frequency replica of the sample on duration (this is because the samples I will be using will be to rich harmonically for the LM576 i am guessing).
    Thus I could have 4 simultaneous tracks of rich audio events sending out logic level signals - "triggered" by 4 seperate "invisible" audio tracks ?
    Wow!
    thanks,
    M
     
  18. retched

    AAC Fanatic!

    Dec 5, 2009
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    Yup, that would work. Just get a signal generator or pulse generator that will create tones outside of human hearing (ultrasonic) and within the specs of the LM576C and you will have a switch to ground at every pulse.
     
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  19. mxabeles

    Thread Starter Active Member

    Apr 25, 2009
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    my mind has been blown to pieces. :cool:
     
  20. retched

    AAC Fanatic!

    Dec 5, 2009
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    Well, make some art to do the same to others. ;)
     
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