Time delay circuit (up to 1ms)

Discussion in 'The Projects Forum' started by M.qrius, Jul 14, 2008.

  1. M.qrius

    Thread Starter New Member

    Jul 14, 2008
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    Hi

    I need a circuit which delays my signal by a value between 0 and 1 ms (or 1 and 2, if that's impossible). Preferably with an easily adjustable time delay, cheap, and not deforming the signal too much (in that order).

    Does such a thing actually exist?
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    What kind of signal, what is it's use?
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    Like Bill's asking, you need to give a LOT more specifics on the signal.

    If it's low voltage and low frequency, it might not be too hard or expensive.

    A shot of an oscilloscope trace with all the relevant settings would be good.
     
  4. M.qrius

    Thread Starter New Member

    Jul 14, 2008
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    Oh sorry, it's a sound signal, as in, from a microphone. Speech range would be nice which is 200 Hz to 8 KHz. The point being that because it's multiple frequencies, a basic phase shift circuit wouldn't work, as far as I can tell.
    It's still a concept at this point so I can't give an oscilloscope shot.
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    Wookie, they still make bucket brigade chips? I seem to remember those doing something like this duty.
     
  6. M.qrius

    Thread Starter New Member

    Jul 14, 2008
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    Sounds like roughly what I'd want.. Too bad they're out of production though. This post is from 2001 however, so maybe something new came onto the market since then?

    I'm not quite sure I understand how the capacitor ladder is supposed to work... any ideas?

    Edit:
    hundreds or thousands... that's a little much to make myself.
     
    Last edited: Jul 15, 2008
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Yeah, Reticon used to make the SAD512 and SAD1024. You can still find datasheets for them, but the IC's themselves are rather hard to find. Years ago, they were popular for use in flangers/chorus effects units. If I remember correctly, AudioGuru had some disparaging comments about the sound quality of the devices that used them. But then again, he's a purist - and you have to respect that.

    Old reverb units actually used just a simple coil spring in tension between a couple of phono or RCA jacks. The diameter, wire gauge, length, and tension on the spring would each affect the sound. These units were fully enclosed metal boxes to limit the effect that external sounds would have on them, and were used on the line-level side, if I recall correctly (I'm going on a 35 year old memory here, so caveat emptor.)

    I believe the modern effects units use an ADC to convert line-level incoming signals to digital. From that point, you'd just queue the bitstream to a FIFO buffer area, and use a DAC on the other end to convert back to analog. This is quite simplified, of course - just the concept.

    I don't see why this couldn't be accomplished using a powerful uC - except the resolution of ADC's in most of them isn't that great. You'd need a fast ADC that could sample at a 44kHz rate, with plenty of bits resolution to avoid losing too much sound quality. On the other end, you'd need a DAC with the same resolution. In between, you'd need to run the signals through optoisolators, and keep the digital side isolated from the analog side.
     
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