LM331 : Frequency to Voltage Converter

Discussion in 'The Projects Forum' started by Saxbel, Dec 15, 2011.

  1. Saxbel

    Thread Starter New Member

    Nov 29, 2011
    Hello everybody,

    I'm a belgian student in engineering and I need your help for an electronic project. I've built a circuit with Shift lights and tachometer for a 4-cylinder engine. Everything is all right but how the LM331 works as a frequency to voltage converter ? Can you explain me that (if possible in french) ?

    Here is a scheme of the LM311 :

    Here is my circuit :
    Thanks for your answer ;)
    Last edited by a moderator: Dec 17, 2011
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    Have you read the text on page 9 in the datasheet, referring to Fig.6?

    BTW, the part number is LM331. LM311 is a comparator.

    Have you looked at LM2907/LM2917?
    Last edited: Dec 15, 2011
  3. Saxbel

    Thread Starter New Member

    Nov 29, 2011
    Oh sorry : yes it's LM331 sorry :(

    Yes but I would like to know how this components works really ? What's the different systems in it and how it works separatly ?

    I've seen the datsheet from LM2907 and 2917 but I don't know if it's the same and I don't understand all about it.

    If you can help me, it's very friendly :)
  4. Saxbel

    Thread Starter New Member

    Nov 29, 2011
    Up please ;)
  5. wayneh


    Sep 9, 2010
    I think you need to ask more specific questions. We cannot guess what aspects of the circuit you don't understand. You don't need to ask all questions at once - just try to explain how it works in your own words and let folks know where your "gaps" are.
  6. Adjuster

    Well-Known Member

    Dec 26, 2010
    The text of this article, http://schema-electronique.blogspot.com/2011/04/un-frequencemetre-analogique-ou-comment.html which may be the source of your block schematic, gives some information. At least the elements within the circuit block are identified.

    Perhaps this reference may help. It seems quite detailed. http://books.google.co.uk/books?id=0LHzObXRK7sC&pg=PA347&lpg=PA347&dq=LM331+donnees+convertisseur&source=bl&ots=eXfuA6XlDF&sig=_J0jB0x2UkdCY_wiIEBj4RHTFKE&hl=en&sa=X&ei=h3vsTruxFILb8QPRwqDzCQ&ved=0CEoQ6AEwBTgK#v=onepage&q=LM331%20donnees%20convertisseur&f=false

    Having said that, one must be careful in using such material in marked assignments. Perhaps it is best to try to understand the material as fully as possible, then express it in your own words. Alternatively, quotations e.g. from a datasheet must be acknowledged. Whatever you do, do not simply cite things without giving any references.
    Last edited: Dec 17, 2011