10 sec. countdown timer with LED display

Discussion in 'The Projects Forum' started by bobank, Sep 12, 2007.

  1. bobank

    bobank Thread Starter Member

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    Is any simple circuit available for countdown timer to start from no more than 10 sec ( can start as low as 3 second and go down.) On 0:00 sec relay activates, It should be able to use 7 segments display. What I want to make is something like clap board for movie clips for sinhronizing cameras. ON flip of a switch, red display start from, let's say 3:00 SECONDS, When it comes to 0:00 secs, relay should be activated, on relay I could connect LED light so something will get both cameras visible signal for first frame. It can work without LED light and relay, but it is easier to notice light than read numbers. Thanks
    Boban Klasnikov
  2. cumesoftware

    cumesoftware Senior Member

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    Is it for a bomb?:D Just kidding.

    You can resort to a variety of TTL or CMOS chips, depending on what you wan't, or a PIC microcontroller instead. So, what tecnology do you have in mind?

    Please give more details about this project. What are the requirements?
  3. bobank

    bobank Thread Starter Member

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    No reqirements, just something to work. My skills in elecronics are the best when:
    1. I come into the store and buy product, and/or,
    2. get schematic and do soldering ( pretty good in that)
    Plus, my free time is unlimited. I bought myself about 10,000.00 dollars electronic laboratory and all I do was to turn on air solder station when is cold in the winter. So, you can guess I live in US. All time spent working so I can afford to buy things that I will never use because I have to work.. That was long answer. The sort is: something that have red numbers and they go down till 0.
    Thanks, boban
  4. Gadget

    Gadget Distinguished Member

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    Bet that comment lit up the board at FBI headquarters... ;)
  5. mozikluv

    mozikluv AAC Fanatic!

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    a cd4510 which is a cmos presettable bcd up/down counter, a cd4511 which is a cmos bcd 7 segment latch decoder and a 555 timer will do for you.:) plus a couple of transistors to drive your relay

    moz
  6. Gadget

    Gadget Distinguished Member

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    I'm guessing if it's for a Clapper Board, your gonna want 100th of a second divisions..... i.e. 10.00 down to 00.00 seconds.
    That will require cascaded counters, and probably a slightly more accurate timebase than a 555.
    A Micro based solution may be tidier, and more compact.
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