On-off timer help, please

Discussion in 'General Electronics Chat' started by Rich B, Jul 26, 2007.

  1. Rich B

    Thread Starter New Member

    Jul 26, 2007
    3
    0
    Good morning,

    Please can you help; excuse my ignorance, but I know very little of electronics?

    I would like to obtain a battery operated (AAA type or similar) module that turns the power on for roughly 3 seconds then off for a further 3 seconds and repeats this indefinitely. From browsing the internet it seems that I may need something called an astable 555 timer?!?!

    Additionally, the complete module must be as small and simple as is possible, ideally not more than 10mm in width and height (length is not so critical, i.e. ideal shape is long and thin). Also, I guess only 2 batteries would fit in my application, so 3v would have to suffice.

    Is it possible that this can be made? If any one can do so I'll gladly pay them to provide a couple! Otherwise, can anyone tell me what components I would need to try myself.

    Many thanks in advance for your time and any help you can provide, Richard
     
  2. lightingman

    Senior Member

    Apr 19, 2007
    374
    22
    Hi,I will help you here.....I need to know what sort of load that you wish to switch......Daniel.
     
  3. Rich B

    Thread Starter New Member

    Jul 26, 2007
    3
    0
    Thanks for your help!

    Now load, umm, right then, what exactly is this? Is it the ampage?

    Well, to explain, I am taking an battery run motor out of a small childrens toy to use for my little invention. Haven't got the toy to hand presently; however, ampage of an AAA is about 1mA isn't it?

    Am I making any sense?

    Rich
     
  4. Rich B

    Thread Starter New Member

    Jul 26, 2007
    3
    0
  5. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    Yes. You want the LMC555 timer from National Semiconductor. The LMC555 operates
    with a Vcc from 1.5V-5V. To drive your fan you need to buffer the output with a
    transistor.

    10mm may be a little tight to do with through-hole components but you may
    be able to squeeze it in. SMD devices would *easily* fit your packaging.

    If you need additional help you can contact be offline (my email address is on
    my website).

    (* jcl *)
     
  6. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    Learned one today. I didn't knew that a LMC555 existed. But is is indeed the CMOS version of the LM555. I think there was also an LM7555, if I'm not mistaken.
     
  7. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    By the way, just corrected a page about the 555 timer on wikipedia. Those guys had National LM1455, LM555C and LMC555 marked as CMOS. The only CMOS version there is the LMC555.

    LOL: http://en.wikipedia.org/wiki/555_timer_IC
     
  8. nanovate

    Distinguished Member

    May 7, 2007
    665
    1
    TI's TLC555 is LinCMOS (tm) device which I believe is just a fancy word for CMOS.

    They also have SA555 and SE555 timers. Anyway there are some many variants and alternate mfgs it is hard to keep track! That 555 really got around.

    John
     
  9. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    Here's another one for you --- Zetex ZSCT1555

    The Zetex part operates down to 0.9V.

    (* jcl *)
     
  10. nanovate

    Distinguished Member

    May 7, 2007
    665
    1
    Actually we should ask "Who doesn't make a 555?" :)
     
  11. lightingman

    Senior Member

    Apr 19, 2007
    374
    22
    Well,

    Seems this one may already be sorted.....

    Daniel.
     
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