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A low voltage replacement of LM3909?

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agis68

New Member
Hallo guys...

I was wondering what is the exact replacement of the LM3909 after the discontinuing of its production. The famous LM3909 had the ability to work and actually to get all of the juices of a single alcalic cell (1,5) and continuing working after the cell droped under the 0,50V for more than 12 months of full working.
Some people saying what we need the old and expensive 3909 when we do the same job with the 555. But there always some deferences:
first of all and correct me if I am wrong the functional range of the 555 starts in 4,5V and gets ideal in 6V and 12V. Instead the old aged 3909 had all its abilities in 1,5V!!!
Also the old chip had a very well regulated and stable time of oscillating.
Have anyone any idea what's the replacement of this? If i had to build a flasher light with the LM3909 i would need just the IC, the led, the resource and the capacitor. That's all!!!
Somebody told me why don't you make an analogue of the IC using the appropriate parts. The answer is obvius: If i had the appropriate space i would do it. But when you have to build an SOS navy flasher in the dimensions of a common flasher then there's no any available space.

Please any recommendation is welcome

PS.....what was the company made that ICs?????
 
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Hero999

Banned

LM3909 Oscillator

I would use 390R rather than the 410R for R4 and R5 as it's a standard value.
 

jbeng

Member
agis68 said:
PS.....what was the company made that ICs?????
National Semiconductor was the manufacturer of the LM3909 ...

Jeff
 

Hero999

Banned
Flashing LED, plus a Joule Thief.

Note that you'll need a zener and capacitor across the LED to protect it from the high voltage when it turns off.
 

mneary

New Member
hmm, that suggests to me that a "flashing Joule Thief" might be simpler than the 3909 alternatives. Good project for 'tomorrow'. (errrr... that is, the other end of tonight.)
 

agis68

New Member
Who decides to cut out some suceded parts?

Dear Friends,

really I love these communities...:)

1. I liked the comment of Whiz115 I believe in ICs too:D
2. Please i need to save space not to waste with all these parts:mad:
3 No flashing Led because u can't adjust the flashing rate and because shelf flashing leds are most not extra bright!!!
 
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audioguru

Well-Known Member
Most Helpful Member
An LM3909 had a minimum supply voltage of 1.15V, not 0.5V. Then its LED was not bright. With a brand new alkaline battery cell (1.6V) then the LED was bright.
 

Hero999

Banned

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Hero999

Banned
You might be able to use it in conjunction with a Joule thief but it's useless on its own because it requires 12V.
 
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