Identify mysterious IC

Discussion in 'General Electronics Chat' started by clack, Jan 29, 2013.

  1. clack

    Thread Starter New Member

    Jan 29, 2013
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    Hello,

    I am currently reversing a simmons claptrap schematic as it is really interesting but it has no information on what the IC's are. I have guessed most of them (a 555, 3080 etc ) bar one which is mysterious. I think it is some kind of logic as it has minimal resistors and it has 1M feedback resistors (linearisation? ) it also seems to be inverting as when the switch is on it turns of a part of the circuit and turns off LED's . I have looked through all the 4000 series and some 74 series but no luck. It seems to have the same output as most dual gates (13 & 1 ) but would you drilve an LED off an input of say a 4002 2 input NOR? doesn't seem right.

    this is my drawing, numbers with question marks are illegible but guessed.

    https://www.dropbox.com/s/ozr9ekankpi6hmv/2013-01-29 08.11.23.jpg

    am I barking up the wrong tree? its a circuit from the early 80's maybe late 70's so I cant imagine it is something particularly exotic.
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Could you post a picture of the top and bottom of the PCB?
    You can upload the pictures to this forum, instead of posting them on dropbox.
    Here are the instructions from the FAQ:
    Attachments and Images

    Bertus
     
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  3. clack

    Thread Starter New Member

    Jan 29, 2013
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    thanks for your reply, ok no problem uploaded it as an attachment.

    I do not have the PCB, I am trying to recreate an old schematic (simmoms analog claptrap ) . I guess its a non standard part but to me it really looks like a standard logic chip.

    I was just trying to see if anyone recognised the configuration, I guessed a 3080, 555 and a lm301 using the same trick.

    back to trawling though datasheets!
     
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  4. bertus

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  5. clack

    Thread Starter New Member

    Jan 29, 2013
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    yep thats the schematic I am working from (its scandalous they charge that much for work that is not their own without a proper parts list ) I am hoping to publish a clean re-drawn proven version.

    as for that thread you actually list my site in your reply! my site is a sort of archive of the designs of synth drums. This section I am currently doing is on Clap designs ( Roland, EHX, simmons, Tama ) they are all quite similar, but the simmons has a really interesting 'humanizer' section

    I attached the small section I am trying to guess, just for interest. See that this IC switches off the LFO (yellow) and the 'humanizer' effect (green). I was just wondering if anyone had a clue, but its cool I will just keep looking around at datasheets.
     
  6. bertus

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    Apr 5, 2008
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  7. Meixner

    Member

    Sep 26, 2011
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    Looking at your drawing my guess is possibly it's a CD4013
     
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  8. clack

    Thread Starter New Member

    Jan 29, 2013
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    meixner! I think you are right, the feedback resistor is to flip and flop the flip flop! I think I had 3 and 5 mixed up because of the clarity of the scan. it could also be an SN7474 as I can see other simmons circuits used TTL.

    Bertus: Thanks for the IC listings I was looking for something like that!
     
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