Building a frequency meter, Any advice?

Discussion in 'Homework Help' started by RTC, Feb 9, 2015.

  1. RTC

    Thread Starter New Member

    Feb 9, 2015
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    Hi

    Currently at university at the moment in first year and been told as a project I must design a and build a frequency meter.

    "you are required to design and build a circuit to display the frequency of a TTL compatible square wave wave. Frequency meters consist of a counter, a display and a gate that is opened and closed under the control of an accurate oscoscillator, plus some control. Your circuit should consist of three seven segment displays and indicate frequency in the range of 0-999hz. Your circuit should freeze the display when the gate closes so that it can be read, and reset it to zero before the gate opens again. It will therefore be necessary to design some gate and reset control circuitry, and possibly latch"

    Above is the exact brief given.

    I'm unsure where to start at the moment my lecturer has only taught us about gates so far.

    So any help being that of youtube videos or websites to read to help me understand to design and build this would be great.

    Many thanks
    Rhys
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Welcome to AAC!
    Then your next step is to google for tutorials on counters and displays.
     
  3. RTC

    Thread Starter New Member

    Feb 9, 2015
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    Cheers

    Started doing that, but at the moment I'm struggling to understand how they all work togethe, to make a frequency meter.

    Will that all become clear once I know enough about them?
     
  4. IcedFruits

    Member

    Jan 15, 2014
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    try to understand something like a zero crossing detector ?
     
  5. #12

    Expert

    Nov 30, 2010
    16,261
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    TTL doesn't cross zero. You're going to be using digital chips to count highs and lows.

    Start with a "block diagram". This is the input, it must have at least this much impedance and that much speed. This is the gate. It must open and close...how fast and how accurate? etc.
     
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  6. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    You will need some time control system to open and close the gate (e.g. Exactly one second).

    Here is the concept. The real work come in the 3-digit display! Not done here!

    image.jpg
     
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  7. Reloadron

    Active Member

    Jan 15, 2015
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    Gopher laid out a good start. Just begin by looking at the blocks and what the building blocks each do. That drawing is a good illustration, really good.

    Ron
     
  8. RTC

    Thread Starter New Member

    Feb 9, 2015
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    Cheers for all your help so far,

    Looks like I have a lot of theory to learn first before I can start trying to tackle designing this.
     
  9. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    RTC likes this.
  10. ScottWang

    Moderator

    Aug 23, 2012
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    You have to find the theory of frequency meter and how many functions it needed, and then solve them one by one, and put them together, the last is to test the function and debug.
     
  11. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Not so much. Look at the list of chip available in the 7400 series and then look into what they do. The datasheets are widely available and straightforward to read. If not, make another post on this thread.

    http://en.wikipedia.org/wiki/List_of_7400_series_integrated_circuits
     
  12. k7elp60

    Senior Member

    Nov 4, 2008
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    I also think the block diagram is great.
     
  13. wmodavis

    Well-Known Member

    Oct 23, 2010
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    I say gophers are much smarter than groundhogs. The GHs can't even predict the weather yet this gopher can simplify a frequency counter right down to the simple basics.
     
  14. IcedFruits

    Member

    Jan 15, 2014
    84
    2
    thanks, missed the ttl part.
     
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