Best Comparators To Simulate LM3914?

Discussion in 'The Projects Forum' started by CDRIVE, Apr 30, 2011.

  1. CDRIVE

    Thread Starter Senior Member

    Jul 1, 2008
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    There's an active post in which the OP is using a Dot/Bar Voltmeter kit. The heart of the kit employs two cascaded LM3914's, of which, I can't find a Spice model for. This is a popular chip, so I really would like to model it. I can do this by building a subcircuit macro using discrete comparator chips but need some opinions first.

    Since I'd prefer to not spend most of my time researching data sheets for the most likely comparator candidate..... Anyone have any opinions - preferences?
     
  2. shortbus

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  3. CDRIVE

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    Thanks, I haven't checked the LT Spice forum. I figured that if there was a relevant LM3914 Spice post it would have popped up while Googling it.

    BTW, while I have LT Spice on this PC, I usually use Tina.
     
  4. Ron H

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    It gets pretty complicated if you really want to get into the guts of it, because of the programmable current sinks on the outputs, among others. If you want to simulate dot mode, it gets even tougher.
    For a simple comparator, use one of the generic op amp models in the LTspice library. They will probably sim faster that something like an LM393/339 or LM311.
     
  5. CDRIVE

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    Ron, thanks for the info. Yes, the current sinks and the dot mode issues will have to be worked out. I'll probably use voltage controlled switches on the outputs of each comparator to switch from bar to dot mode.
     
  6. Audioguru

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    Why simulate an LM3914? Simply build the circuit instead.
     
  7. CDRIVE

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    Why I want to simulate it rather than build it is irrelevant. I'm old enough,.. like you, to know what I want and what I don't. If you want a long dissertation of why I want it I can provide that but I thought I explained that in my first post.
     
  8. Ron H

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    Cascading also brings complications.
    I think I have a half-finished 3914 model that I was working on. I'll look it up when I get a chance.
     
  9. CDRIVE

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    Ron, with any luck you have a better track record for finishing projects than I do. When I was young I finished everything I started. Not so much these days. ;) Btw, is that a pspice model or subcircuit macro?

    Chris
     
  10. Ron H

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    It's in LTspice, and the intention was to develop a behavioral model which could be used as a subcircuit. I've been playing with it just now, and it has a long way to go to include all the functions. Even what I have now runs pretty slowly. I have some ideas to speed it up, but I'm not exactly a guru when it comes to developing behavioral models.
    I'm an old geezer. I'm famous for not finishing my hobby projects, as I am reminded of frequently by my wife.
     
  11. retched

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    WOW!, I am famous for leaving women who complain about my hobby projects! ;)
     
  12. shortbus

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    :) I'm just the opposite, I have unfinished projects because of women:)
     
  13. CDRIVE

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    That is a wife's lot in life! :D
     
  14. CDRIVE

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    That's because you guys have not yet reached the age where what you're ultimately talking about is considered "hard work". ... No pun intended. :D
     
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