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COMPLEX SOUND CHIP 76477

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by MrDEB, Feb 20, 2016.

?

Any interest in boards

  1. Sdip adapter board to adapt from 1.77 pitch to 2.54 pitch

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  2. A 3 "x 4" aprox PC board for a complex sound circuit using a 76477 chip and a 555 chip

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Multiple votes are allowed.
  1. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Is that the same theory that says when you need a little more money you can extend past your overdraft? lol:p
     
  2. MrDEB

    MrDEB Active Member

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    after reading post 96 I found several other issues concerning the 555 connections. Made changes and will recheck the ground.
    Made all the traces .020
     
  3. MrDEB

    MrDEB Active Member

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    Sorry but the traces you pointed out are the 5+ . No problem with ground as there are 3 ground connections to panel stuff on the board.
    Thanks for looking as it has helped locate other issues (555 connections)
     
  4. dave

    Dave New Member

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  5. JonSea

    JonSea Well-Known Member

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    The area I circled is part of the ground plane. Because of where you have located components and pads, and the isolation (clearance distance) to other traces, this "island" of ground plane has only one connection to ground, by the trace from pin 2 on the IC to the ground connection pad at the top of the board. It's desirable for the ground plane to be as continuous as possible, with no large marginally connected peninsulas.
     
  6. JonSea

    JonSea Well-Known Member

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    I am all-to-familiar with breaks in the ground plane. On the original TAP-28 board, last minute changes to the header connectors meant there wasn't clearance for the ground plane to flow between the header pins. The left the top central area separated from the bottom central area in the drawing below. A jumper had to be soldered across the break for the ground plane sections to be connected and for the broad to work, as shown by the magenta jumper on the right side of the board.

    Since I have experienced this problem, it's one I'm extremely careful about. I'm trying to pass some of my experience on for what it's worth [comment redacted].

    The two ground plane areas on your board are not completely disconnected, but they are connected only by a 12 mil trace. Not good form and may well lead to problems particularly with an audio circuit.

    I've tried to help. I'm done.

    TAP-28 Gnd Plane Break.jpg
     
  7. MrDEB

    MrDEB Active Member

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    I appreciate your input, in fact I look forward to it. I wouldn't have seen the issue with the 555 connections.
    Will see what I cam move to correct the ground plane issue.
     
  8. MrDEB

    MrDEB Active Member

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  9. JonSea

    JonSea Well-Known Member

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    That was fun...for 15 seconds.
     
    • Agree Agree x 1
  10. MrDEB

    MrDEB Active Member

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    you lasted 15 seconds??
    I figured LGM might enjoy reading what other people have done with the 76477 and an Adrino.
    It sounds like a neat idea to mix a 76477 complex sound chip with a micro controller but I would think there would need to have a lot of additional parts like digital pots. Maybe a digital capacitor?? if there is such a beast.
     
  11. JonSea

    JonSea Well-Known Member

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    I lasted almost to the end of the video...hoping for something spetacular! Spoiler alert - after 15 seconds, you've heard everything you're going to hear!

    I think the chip may be capable of more, but that guy wasn't doing it.
     
  12. MrDEB

    MrDEB Active Member

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    I often wondered about combining the thermin with this chip.
    using the metal strips and touching with a finger to change the capacitance and resistance??
    Whole other project.
    I need to order some boards to do some actual experimenting and building the unit for grandsons as per schematic in data sheet.
     
  13. atferrari

    atferrari Well-Known Member

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    The French magazine Radio Plans Loisirs, did run, more than 25 years ago several articles with valid examples of sounds (not always simple ones), that anyone could implement. For this kind of things I suspect that besides knowing how it works, you need some creativity. Or it is ability to think out of the box?.

    /Edit
    It was reading the datasheet that I heard for the first time about the concept of ADSR.
    Edit/
     
    Last edited: Mar 21, 2016
  14. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    I am still waiting for my chip!! was ment to be from the UK but I have a feeling one hung low is telling lie and chip come from china. I will try and find one with 24-48 hour delivery, I love all the second guessing of what I have in mind! Most is way off. You dont have to over complicate it to make it great ;), digital resistors ect are not needed, simple switches in a dip package are fine as would be a R2R DAC ;)
     
  15. JonSea

    JonSea Well-Known Member

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    That's what's great about electronics - there all always many different ways to approach a solution, and usually no single best way.

    Looking at the schematic, i see that all the resistors and capacitors are connected to ground. Would it work to ground these through an open-collector buffer?
     
  16. Mikebits

    Mikebits Well-Known Member

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    Indeed, I would say that is what much of engineering is, compromise. Capacitors are prime example, dielectric constant κ, for example. Low κ values give a more linear response over temp where high κ is very non-linear (which sometimes can be used to our advantage), so somewhere in between is usually chosen to give best performance for the specification of importance.
     
  17. JonSea

    JonSea Well-Known Member

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    Not even at that level. You could use this chip in the circuit shown in the data sheet. Or you might use digipots and analog switches Or whatever ingenious method LGM is soon to show us.
     
  18. MrDEB

    MrDEB Active Member

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  19. MrDEB

    MrDEB Active Member

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    I have not forgotten this project, just waiting for circuit boards. Contacted the company and appearently the boards got stuck over at customs. The boards were mailed out 5 weeks ago.
    either order more boards or ??
    It's not the board house fault.
     
  20. JonSea

    JonSea Well-Known Member

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    I get consistent 1 week delivery from Elecrow using DHL Shenzeng shipping. I order boards Sunday night and they are here the following Monday without fail.

    Shipping from Hong Kong often results in delays and saving a few bucks on shipping isn't worth the savings on anything that matters.
     
  21. MrDEB

    MrDEB Active Member

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    I ordered from one of your recommendations but have yet to receive. Reordering from Elcrow today.
    Still held up or lost in customs.
     

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