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555 timer. Where?

  • 09-11-2010 11:37pm
    #1
    imjustthetruth
    Closed Accounts Posts: 5 ✭


    Hello,
    I am trying to find a 555 ic timer on old circuit boards. So far I have gone through stereo system and tv but have not been able to find one. What electronic devices would have a 555 timer in?

    Thanks in advance


Comments

  • #2
    langdang
    Closed Accounts Posts: 3,864 ✭✭✭langdang


    A first year electronics project?
    You'd have to be going way back to find any consumer item that actually had one - maybe some clock radio from the 70's?


  • #3
    DublinDilbert
    Registered Users Posts: 5,365 ✭✭✭DublinDilbert


    You'd be best off just buying some from radionics, maplin, online... They are still used to this day.

    If you have trouble getting one send me a pm I'm sure I have some around somewhere...


  • #4
    imjustthetruth
    Closed Accounts Posts: 5 ✭imjustthetruth


    Thanks for the quick replies. I will get onto the net now. Didnt think would be so hard to find


  • #5
    FarmerGreen
    Registered Users Posts: 1,134 ✭✭✭FarmerGreen


    More used in industrial control stuff really.
    Cheap as chips 0.25c each, for which you get a 1/3 , 2/3 comparator , latch , and other stuff.
    Very useful little gadget.
    Theres a CMOS version as well, 7555.


  • #6
    Gurgle
    Closed Accounts Posts: 5,064 ✭✭✭Gurgle


    imjustthetruth wrote: »
    I am trying to find a 555 ic timer on old circuit boards.
    Most mass produced products have custom marking on its components, you won't find a chip with '555' printed on it. Build a test circuit on a breadboard and try any 8-pin chips you find.

    (Or just buy from Farnell or similar for < €1)


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  • #7
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,681 Mod ✭✭✭✭Capt'n Midnight


    Radionics
    Franell
    Maplins
    Peats


    I don't like 555's because they don't provide equal mark to space ratios and the bipolar version can produce a lot of electrical noise on the power rail.

    Schmitt triggers make nice oscillators with far fewer components.
    CLK10.gif


  • #8
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,681 Mod ✭✭✭✭Capt'n Midnight


    actually I can't remember seeing 555's in any mass produced circuits -- even though over a billion of them were made

    Quartz crystals meant you got stable times - and you didn't need a 555 for them - just a counter / divider many of which had an oscillator built in


    http://www.donberg.ie - do mail order electronics from Donegal btw.


  • #9
    FarmerGreen
    Registered Users Posts: 1,134 ✭✭✭FarmerGreen


    See the ICM7555 datasheet :-
    http://www.intersil.com/data/fn/fn2867.pdf

    "The circuit can be connected to trigger itself and free run as
    a multivibrator, see Figure 2A. The output swings from rail to
    rail, and is a true 50% duty cycle square wave. "


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