LM 3909 near equivalent circuit...

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Externet
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LM 3909 near equivalent circuit...

Post by Externet » Mon Sep 05, 2005 8:37 pm

Hi.
Many of you that would like such flasher ic cannot find it.<p>=========================================
Well, hookup a 74HCT04 this way:
Better draw a rectangle, on top, leave a line for pin 14 (+); at the bottom one line for pin 7(gnd), on one side, leave 4 lines; these will be from top to bottom:
pin 4, pin 1, pin 3, pin 2
Pin 4 goes to a 33µF Tn and to a 0.33µF
Pin 1 goes to the 0.33µF above and to a 2.2MΩ
Pin 3 goes to the 2.2MΩ above and to a 0.34µF
Pin 2 goes to the 0.34µF above and to a 34µF Tn
The other side of 33µF goes to a 11KΩ resistor
and to LED
The other side of the 11KΩ resistor goes to pin 14 which is also +2V supply.
The other side of 34µF goes to LED and to a 11.1KΩ resistor.
The other side of the 11.1KΩ goes to pin 7 which is also gnd.
Use a highly efficient LED. Other pins not used. The odd values are just to identify them while drawing, use nearest values.
================================================
Parts list
1x 74HCT04
2x 33µF
2x 0.33µF
1x 2.2MΩ
2x 11KΩ
1x red LED
================================================<p>Pin 14 = +2V (usually works with less) I use a green LED as zener. To power from 12V:<p>+12V------1KΩ------P------|>|------Gnd<p>(P is 2V power node to feed the 74HCT04 circuit ; the diode is a green led.)
It's been working in my car dash for a year.
Sorry, could draw the schematic with software but am an idiot with no skills to attach it. :)<p>[ September 05, 2005: Message edited by: Externet ]</p>
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Chris Smith
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Re: LM 3909 near equivalent circuit...

Post by Chris Smith » Mon Sep 05, 2005 9:13 pm

You can actually find the equivalent circuit inside the part referred to as a “Flashing Led” and you can even use this whole led to run other strings of LEDS using a transistor, or direct wiring it to another Led, as long as you don’t overload the original “flashing led”.

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Re: LM 3909 near equivalent circuit...

Post by Externet » Mon Sep 05, 2005 9:22 pm

And what is the minimum voltage those self-flashing leds work with ? Is it 1.2V? 2V? and its duty cycle and power consumption?
Miguel
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Re: LM 3909 near equivalent circuit...

Post by VIRAND » Mon Sep 05, 2005 10:10 pm

This link has a replacement schematic for the LM3909.<p>http://home.cogeco.ca/~rpaisley4/LM3909.html<p>I put the LED flashers in trees as a child for weird reasons and many of them are still flashing today!<p>The chip had a lot of incredibly obscure uses also, which had nothing to do with LED's and a lot to do with sound.

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Re: LM 3909 near equivalent circuit...

Post by sofaspud » Mon Sep 05, 2005 11:40 pm

Yeah, the LM3909 makes a great little 1kHz audio oscillator. Very handy for repair work and will run forever on a couple of AAA cells.
That link doesn't specify the zener diode but according to a datasheet I have it's 6.5V.

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Re: LM 3909 near equivalent circuit...

Post by L. Daniel Rosa » Tue Sep 06, 2005 12:29 pm

Now that chip could probably be raplaced by a microcontroller. I've tested a few at 1.2 volts and all will start with a 32kHz crystal. I should try a few with internal oscillators.

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Re: LM 3909 near equivalent circuit...

Post by Chris Smith » Tue Sep 06, 2005 1:10 pm

I have a jumbo 12 volt one, and their duty cycle is set by the flasher inside unless you have a microscope and cutter, then you can change its values? They make low power ones that run in the 6 volt and lower range.<p>50% duty cycle is the norm, one second interval "blinks".

Varying the load and voltage slightly with out burning it out, changes the cycle rate slightly. <p>This can be set to trigger the base of a Transistor, to set off as many LEDS as you like.<p>I also found a site that has in stock 888 lm3909s.<p>http://www.digitroncorp.com/part/LM3909<p>Also.... Here is a three volt multi led operation. <p>http://www.elecdesign.com/Articles/Arti ... /8935.html<p>The ubiquitous LED continues to expand frontiers and applications with a plethora of sizes, colors, and output lumens. Flashing LEDs that incorporate internal electronics for oscillation offer embedded applications the advantage of size. However, designs that require multiple flashing LEDs are impeded by the reality that individual flashing LEDs are automatons and will blink asynchronously. In addition, these flashers can be an order of magnitude more expensive than their nonflashing brethren. <p>Here's a way to economically synchronize an array of standard LEDs using only two additional components (see the figure). A flashing LED is required to "set the pace" of the standard "slave" LEDs. When the flashing LED turns on, its corresponding current is sensed by the transistor via the 47-(omega) resistor. The transistor's collector current then drives the standard LEDs. <p>[ September 06, 2005: Message edited by: Chris Smith ]</p>

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Re: LM 3909 near equivalent circuit...

Post by Edd » Tue Sep 06, 2005 6:48 pm

Aaay Miguel …¿.Kay Towel ?<p>Well, I thought that I would plot out a schema for your described low voltage repeat...LOW VOLTAGE operating CMOS ckt...in keeping with the main capability of the original LM3909 IC circuit...by using your info supplied.
Logically, the 12 VDC supply went to a 1k curr lim resistor and on to a green LED with that juncture feeding to pin 14 of the 7404 for Vcc ....with its pin 7 to gnd...thereby getting the power interfacing to the IC.
Then I was successful in sequentially making the component interconnects within the suggested block layout.
Parts were falling into place, up to the point where pin 2 had its "34µF Tn'' cap hanging off to be terminated... (along with the earlier open end of ''33µF Tn '' floating off from pin 4 in a likewise manner)
After that, the described further interconnection sequencing order to the LED and the "11k" resistors became somewhat vague and questionable.
At that point I switched to recreating the drawing utilizing logic inverter symbols in a schematic layout, instead of the previous block layout, then possibly expecting to see a switched capacitor voltage pump up circuit be materializing from the interconnects, along with a low freq osc/pulse gen to slow pump the LED, but it never showed itself using the way I had interpreted the described interconnects.
I initially thought that the novel "designation'' of the variants of the 3 sets of duplicate parts might work out OK, but after trying to interconnect to the two "floating 'lytics and the two 10k resistors and the LED , they seemed to be only creating some degree of questionability .<p>Soooooo...might I possibly suggest that you recreate the "verbal semantics" schematic with clarification by using:<p>33ufd(A) 'lytic along with its designated + or - lead
33ufd(B) 'lytic along with its designated + or - lead
0.33ufd(A)'lytic along with its designated + or - lead
0.33ufd(A)'lytic along with its designated + or - lead
[Exclude the above 2 caps if not electrolytics, as otherwise they were unambiguous in their installation, as was the 2.2 meg resistor]
10K(1) res with its leads A & B
10K(2) res with its leads A & B
LED with its designated anode and cathode leads<p>BTW.....what function did the LED unit serve in your automobubble....eye candy.........a car alarm "armed" indicator (either in reality or a "fake" one) and was the green LED ''ersatz zener'' one visable adjunct to it also ?<p>ADDENDA
A last minute forgotten aside for Sir Christopher:
At about the same time frame as your parasitic LED flasher circuit, did you also happen to catch the modicum of simplicity /vs /functionality as being all encompassed within the circuit of:
http://www.elecdesign.com/Files/29/1823/Figure_01.gif <p>
73's de Edd
[email protected] .........(Interstellar~~~~Warp~~~Speed)
[email protected].........(Firewalled-Spam*Cookies*Crumbs)
;) ;) <p>On the side window of my new car there is a sticker that reads" This vehicle is protected by a passive security system". I didn't know what that meant until I touched the door and heard, " Aw c'mon......... go away................ Pleeeeease."<p>[ September 06, 2005: Message edited by: Edd Whatley ]</p>

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Chris Smith
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Re: LM 3909 near equivalent circuit...

Post by Chris Smith » Tue Sep 06, 2005 7:10 pm

Miguel. <p>Batteries come in 1.2v, 1.5 volts, and three volts for two. <p>Who needs/ uses 2 volts, and where can you get 2 volts other than 2.4 dropped?<p>Three volts and the flashing Led works quite well.

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Re: LM 3909 near equivalent circuit...

Post by VIRAND » Tue Sep 06, 2005 10:58 pm

Lead acid cells are 2 volts and it is sufficient to light an LED by wrapping two strips of clean Lead (Pb) in insoluble cloth soaked with citrus, charging it up, and then for safety, maybe, potting it in epoxy. Beware:Chemistry is practically always toxic. Commercial lead+acid cells may be expensive, but the DIY works better than other battery experiments I've tried, it actually makes 2V and lights up LED's!<p>I have not upgraded to 1 volt cmos IC's, and LED's don't run on one volt, but I do think that an oscillator based on old germanium transistors and a voltage doubler based on "crystal" diodes and capacitors may light an LED. <p>I think one germanium transistor and one center tapped audio transistor can flash an LED "like" a LM3909 on half a volt for a long time, the same can be rewired to blink a NE-2. If I remember right...
Collector to primary winding
Base to primary winding through parallel R and C.
Emitter to voltage source (+ for PNP)
Center tap to voltage source.
Secondary to LED or NE-2
...and this may work at 0.3 volts or 9 volts.
R and C may be unnecessary for 0.3 volts.
47K and 0.47uF seem roughly good.<p>Here you have a few parts for trial and error until it works, depending very much on what you have to work with. If you have only silicon,
you just can't get it to work below Half a volt.
One volt? Sure! No problem.<p>Footnote for blinking the neon bulb with this:
"103 simple transistor projects"-Kneitel
ISBN 0-8104-0313-7 Hayden Publishing 1978 pg.17
R=330K C=10uF B=6V
T="universal output transformer"
Q1=2N241
The schematic has an apparently useless 1K pot on the base, what's less than 1K doing next to 330K?

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Chris Smith
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Re: LM 3909 near equivalent circuit...

Post by Chris Smith » Tue Sep 06, 2005 11:22 pm

Practically speaking, we all use standard batteries. <p>2 volts I have, in a six pack. <p>I even have a few cells on their own, but for practical purposes we all chose a standard battery pack and go from there?<p> Low voltage situations are RARE, and for the most part unnecessary.<p> My 4.5 volt 2 amp NIMH pack is smaller than my 2 volt single cell of half the power and voltage. <p>And then, the three volt circuit that I posted can do it all. 2 AAA batteries, or smaller.

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Re: LM 3909 near equivalent circuit...

Post by Edd » Mon Sep 19, 2005 1:51 pm

Seeeñor Miguel.....et al...
A later reviewing of the text of your "verbal-matic" schematic resulted in the logical plotting of a block diagram of your circuit. Then a move was made to its transition into a schematic where a logical assessment of the select few polarity sensitive components could be ascertained. I submit the attached block diagram below and the companion schematic(s).<p>;) ;) <p>Now…some fascinating medical news:
Doctors are now starting to use maggots to heal wounds. This just doesn't make any sense to me.
Now I ask you....when is the last time you saw an animal on the side of the road, covered with maggots, that looked like it was getting any better ?

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Re: LM 3909 near equivalent circuit...

Post by Newz2000 » Mon Sep 19, 2005 2:09 pm

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Edd Whatley:
Seeeñor Miguel.....et al...
A later reviewing of the text of your "verbal-matic" schematic resulted in the logical plotting of a block diagram of your circuit. Then a move was made to its transition into a schematic... <<img>>
<hr></blockquote>
Wow!<p> <blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>The unit reliably kicked right off...<hr></blockquote>
Wow!<p> <blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>However, the second thing noticed was a strong / wideband RFI presence...<hr></blockquote>
Wow!<p> <blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Now…some fascinating medical news:
Doctors are now starting to use maggots to heal wounds...
<hr></blockquote>
Wow!<p>[ September 19, 2005: Message edited by: Matt Nuzum ]</p>

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