Equivalent IC

bertus

Joined Apr 5, 2008
20,653
Hello,

I could not find an equivalent IC.
I found a little circuit to let more leds flash using 1 flashled.
D7 is a flashled, the current it draws will trigger the transistor to let the other leds (D1-D6) flash too.
The circiut comes from a dutch cirtcuit site.
I think it would be safer to put a resistor in series with the leds D1-D6 to limit the current.
The number of leds is dependent on the color you want to use (red and green are ca. 1.7-2 Volts, bleu and white are ca. 3.5-4 Volts).

Greetings,
Bertus
 

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SgtWookie

Joined Jul 17, 2007
22,210
Take a look at Bill Bowden's 1.5v dual LED flasher. It's not exactly like the LM3909, but it does something quite similar using parts that you can still get; flashes a pair of LEDs for a year with just one D cell:
http://ourworld.compuserve.com/homepages/Bill_Bowden/page5.htm

Now, it IS possible to build an LM3909 from discrete components. Rob Paisley shows how on his site:
http://home.cogeco.ca/~rpaisley4/LM3909.html

Of course, a "home made" LM3909 will take up more PCB real estate than the IC, but if you really want to emulate the original, there ya go.
 
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