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What are the alternatives of LED Flasher/Oscillator LM3909?

Discussion in 'General Electronics Chat' started by alanzhao, Jan 23, 2004.

  1. alanzhao

    alanzhao New Member

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    What are the alternatives of LED Flasher/Oscillator LM3909?

    Thanks!
     
  2. Johnson777717

    Johnson777717 New Member

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    The best alternative that I know of would be a 555 timer. It's basically the same thing, and in my opionion, more versatile. These IC's are very cheap, and available at Radio Shack, as well as any electronic supplier. If they don't have 555 timers, then there's something wrong. Check the pin outs for the 555 timer versus the 3909.

    Check here for a pretty brief 555 timer tutorial:
    http://www.meridianelectronics.ca/gadgets/555/555.html

    Pretty much every major non-specialized semiconductor manufacturer has a 555 timer that they make. National Semiconductor = LM555. NTE = NTE955M etc.
     
  3. k7elp60

    k7elp60 Active Member

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    LM3909 replacement

    The easiest replacement for the LM3909 is a standard flashing LED, although you cannot set the flash rate.
     
  4. dave

    Dave New Member

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  5. Roff

    Roff Well-Known Member

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    Do a Google search for "1.5 volt LED flasher".
     
  6. captainkirksdog

    captainkirksdog Member

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  7. Rescyou

    Rescyou New Member

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    3909

    You can still buy LM3909's at www.futurlec.com if you are looking for some.

    Resc.
     
  8. alanzhao

    alanzhao New Member

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    resyou, LM3909 is expensive at www.futurlec.com, do you know anywhere has cheaper LM3909? :lol:
     
  9. bogdanfirst

    bogdanfirst New Member

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    LM3909 is not intereting...
    for a 1.5V flasher use a COMOS 555 like ZSCT1555(works down to 0.9V).
    also try LMC555, TLC555 ICM7555
     
  10. alanzhao

    alanzhao New Member

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    Does anyone have LED flasher circuit diagram using 1.5-3v battery and 555 timer?

    thanks!
     
  11. laroche73

    laroche73 New Member

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  12. duffman

    duffman Member

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    I found a 555 oscillator replacement for the lm 3909 in the Trackign transmitter but it uses a 6 volt power supply.

    The components are a 10 uf electric cap
    a .01 uf ceramic cap
    a 22 resister
    a 10k resiter
    and a 330 resister.

    HOw do I convert these to 1.5 volts?
     
  13. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You don't!. Most electronics won't work off such a low voltage, the LM3909 was specially designed to do so.
     
  14. duffman

    duffman Member

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    fascinating!! so a 555 timer circuit at 6 volts, uses the same components at 3 volt?! thats awesome. But doesnt the rate of flashing and all that rely partially on voltage?
     
  15. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    It's fairly independent of supply voltage, basically because it charges a capacitor to a percentage of the supply, not to a specific voltage.
     
  16. Roff

    Roff Well-Known Member

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    The problem is overcoming the LED forward voltage drop while using a 1.5v (or less) supply.
     
  17. k7elp60

    k7elp60 Active Member

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    Here is a circuit that uses a 74AC14. I downloaded it sometime ago
    from the internet.

    Please ignore my post, I could not get the schematic to upload.
     
  18. duffman

    duffman Member

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    Ok. Well, this is all related to building the tracking transmitter I'm assuming. THis is what started it all anyways.

    It seems to me that all the 3909 did was provide an oscillating signal, that would be put through the coil. Wouldn't a blinking LED do the same thing? Granted it would need 3 volts, which would bring me to our next question. What would running the transmitter circuit at 3 volts do. Wouild it change the frequency? WOuld it make the signal stronger? Also I have a question about inducting signals with coils. This seems like a very crude way to do it. Using wire and all. However, does the wire affect the signal produced. I am using braided wire instead of solid wire and I was wondering if that was affecting anything.

    Also, in different posts, people have talked about how they tried to breadboard RF circuits and came up with unsatisfactory results because of built in capacitance from the breadboard. would this also apply to the tracking transmitter circuit?
     
  19. Proton

    Proton New Member

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  20. Hero999

    Hero999 Banned

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    No problem, the 555 can act as a voltage doubler.
     

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  21. mneary

    mneary New Member

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    I found this in a quick search.... four transistors and a few resistors.

    [edit] I just noticed that the OP hasn't posted anything since Feb. 2004. :eek: [/edit]
     
    Last edited: May 10, 2007

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