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'[EE] A replacement for the LM3909?'
2005\08\03@185255 by Matthew Miller

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face
Hi,

I'm wondering if anyone is aware of a replacement for the LM3909 chip. This
is a very handy LED flashing chip that will run off a 1.5V battery and is
sadly no longer available. Does a good substitute exist?

Matthew

--
Quoth the Penguin, "pipe grep more!"

2005\08\03@185936 by PicDude

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face
PIC12F or PIC10F ?

Cheers,
-Neil.


On Wednesday 03 August 2005 05:52 pm, Matthew Miller scribbled:
> Hi,
>
> I'm wondering if anyone is aware of a replacement for the LM3909 chip. This
> is a very handy LED flashing chip that will run off a 1.5V battery and is
> sadly no longer available. Does a good substitute exist?
>
> Matthew


2005\08\03@191226 by Robert Rolf

picon face
Since this is a PIC list, why not a 10F2xx series
part? Sot23-6, 25mA drive, ICSP.
You could blink out morse code or BCD time if you
wanted.

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2061&param=en505736

Robert

Matthew Miller wrote:

> Hi,
>
> I'm wondering if anyone is aware of a replacement for the LM3909 chip. This
> is a very handy LED flashing chip that will run off a 1.5V battery and is
> sadly no longer available. Does a good substitute exist?
>
> Matthew
>

2005\08\03@191923 by Jinx

face picon face

> PIC12F or PIC10F ?

Vcc = 1.5V ?

2005\08\03@192607 by Jinx

face picon face
Re my "Vcc = 1.5V ?"

Just wondering - it would be possible to make a 10F generate
its own in-spec Vcc from a 1.5V cell ? If you powered up with
1.5V and switched a cap (transistor - FET ?) to get Vcc over
2V so the 10F would boot, then have the 10F s/w oscillate a
pin to drive a voltage doubler to feed Vcc


2005\08\03@194500 by Robert Rolf

picon face
Depending on the temperature, the chip would probably run
at 1.5V. I have an 16LF876 that ran at 1.2V (1.8Mhz) even though
the spec says 2V.


Jinx wrote:

> Re my "Vcc = 1.5V ?"
>
> Just wondering - it would be possible to make a 10F generate
> its own in-spec Vcc from a 1.5V cell ? If you powered up with
> 1.5V and switched a cap (transistor - FET ?) to get Vcc over
> 2V so the 10F would boot, then have the 10F s/w oscillate a
> pin to drive a voltage doubler to feed Vcc
>
>

2005\08\03@194900 by Matthew Miller

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Hi Robert,

On Wed, Aug 03, 2005 at 05:12:03PM -0600, Robert Rolf wrote:
> Since this is a PIC list, why not a 10F2xx series
> part? Sot23-6, 25mA drive, ICSP.
> You could blink out morse code or BCD time if you
> wanted.
>
> http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2061&param=en505736

Now [EE] was put in the subject for a reason... ;) You must not be aware of
the paragon of efficiency that is the LM3909. I have LED flashers that run
for years on one 1.5V D battery! I have no more LM3909 chips though. I'm
looking for a replacement, one that doesn't cost $10 a chip.

Matthew

-- "Man könnte froh sein, wenn die Luft so rein wäre wie das Bier"
"One could be happy if the air were as pure as the beer

2005\08\03@202320 by Jinx

face picon face
> Now [EE] was put in the subject for a reason... ;) You must
> not be aware of the paragon of efficiency that is the LM3909

550uA operating current isn't *that* efficient these days. A sleeping
12F will beat that by a factor of 500,000 !!! A sleeping 10F by a
factor of 5,000. Both have wake-up WDT, you can work out the
average LED-driving consumption

BTW, a discrete clone

http://home.cogeco.ca/~rpaisley4/LM3909.html

2005\08\03@202357 by Philip Pemberton

face picon face
In message <spam_OUT20050803234856.GB9729TakeThisOuTspamnaxs.net>
         Matthew Miller <.....namiller2KILLspamspam@spam@naxs.net> wrote:

> Now [EE] was put in the subject for a reason... ;) You must not be aware of
> the paragon of efficiency that is the LM3909. I have LED flashers that run
> for years on one 1.5V D battery! I have no more LM3909 chips though. I'm
> looking for a replacement, one that doesn't cost $10 a chip.

Build one out of SMD transistors and other bits?

Is there a block diagram or schematic in the datasheet?

Later.
--
Phil.                              | Acorn RiscPC600 SA220 64MB+6GB 100baseT
philpemspamKILLspamphilpem.me.uk              | Athlon64 3200+ A8VDeluxe R2 512MB+100GB
http://www.philpem.me.uk/          | Sony MZ-N710 NetMD Minidisc
... Get 'em by the balls and their hearts and minds will follow.

2005\08\03@211138 by Russell McMahon

face
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part 1 1379 bytes content-type:text/plain; (decoded 7bit)

> I'm wondering if anyone is aware of a replacement for the LM3909
> chip. This
> is a very handy LED flashing chip that will run off a 1.5V battery
> and is
> sadly no longer available. Does a good substitute exist?

The attached circuit, which I "invented" based on a vvv old flasher
cct, may be useful depending on how you want to use it. All I did was
add the L - I assume many others have dome the same. It works but can
be finnicky. There's more to getting it right than meets the eye. As
shown it has minimum component count but an extra R or two can help.

I posted this about 2.5 years ago so there will be discussion in the
archives back then.

LED2 load position adds Vbattery to Vflyback but may not fully
visually extinguish the LED during off times depending on LEd
characteristics.

LED1 position uses only flyback energy. You may need to invert your
brain to understand how it lights with the polarity shown :-). (People
who already have inverted brains will have no problem).

Play with components. Add extra components as desired. eg a resistor
in series with cap will alter discharge time.
R2 must be high enough that base current x Bet1 x Beta2 will not hold
load on at end of flash cycle.
Q1b-Q2c needs a resistor if Vbat > 1 cell and may benefit even with 1
cell.




       RM


part 2 1637 bytes content-type:image/gif; (decode)


part 3 35 bytes content-type:text/plain; charset="us-ascii"
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2005\08\04@001954 by William Chops Westfield

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On Aug 3, 2005, at 4:48 PM, Matthew Miller wrote:

> Now [EE] was put in the subject for a reason... ;) You must not be  
> aware of
> the paragon of efficiency that is the LM3909. I have LED flashers that  
> run
> for years on one 1.5V D battery!

Efficiency, hah!  More like stinginess.  I was always a bit disappointed
in the results of 3909 circuits.  Since the typical 'flash' was derived
by discharging a 300uF cap through the LED (in series with the battery
to get enough voltage), it was both rather dim and rather short in
duration...

The 3909 came at a time before modern CMOS logic, and before boost
mode switching regulators.  IMHO, there are better ways to accomplish
the same thing now (still, I've been a bit surprised that no one has
put a "low current consumption "flash"" capability in the various white
LED driver chips that are around.  Seems like it would be a trivial
addition, and worth it just to eliminate interest in the 3909...)

Someone has already posted the discreet replacement:

   http://home.cogeco.ca/~rpaisley4/LM3909.html

There are some other 1.5V LED flashers here:

   
http://ourworld.compuserve.com/homepages/Bill_Bowden/
page10.htm#15flash.gif

(some dependent on HC logic families seeming to operate down to 1.5V,
which I'm not sure is fair...)

The idea to use a PIC isn't as silly as it sounds, especially for  
something
that will operate continuously.  I can envision a PIC driving a voltage
converter that drives both an LED AND itself.  It might need a button
push to bootstrap itself, but after that it should be pretty easy for  
the
PIC to generate enough 4V or so to power an LED for a tenth of a second
PLUS itself for the second or two till the next flash is supposed to  
occur.
Might be a good entry for one of those contests coming up...  (Mine!)

BillW

2005\08\04@041404 by Tony Smith

picon face
> Hi,
>
> I'm wondering if anyone is aware of a replacement for the LM3909 chip.
> This
> is a very handy LED flashing chip that will run off a 1.5V battery and is
> sadly no longer available. Does a good substitute exist?
>
> Matthew


You can still get them, but you might not like the price.  Futurlec @
$US2.45 - http://www.futurlec.com/Linear/LM3909Npr.shtml

Anyone know what chip bicycle flashers use?  They're 1.5v, blink AND have
on/off.  Must be billions of the buggers made, but buying one in a DIP or
SMT (as opposed to 1,000,000 for chip-on-board) is a bit hard.

Tony

2005\08\04@043231 by William Chops Westfield

face picon face
On Aug 4, 2005, at 1:14 AM, Tony Smith wrote:

> Anyone know what chip bicycle flashers use?  They're 1.5v, blink AND
> have
> on/off.  Must be billions of the buggers made...

I don't think I've ever seen one that ran off 1.5V; most use several
cells.  In fact, I might add "improved batteries" to the list of thing
leading to the demise of the 3909 - even the smallest, cheapest (thing
trade show giveaway) blinky things throw in extra batteries.
When you can go to a web site and buy a couple lithium batteries,
several LEDs, a COB IC to drive them, and some magnets to hold them
somewhere, all for less than $2 in ones; why would anyone use a 3909?

BillW

2005\08\04@045755 by Tony Smith

picon face
>> Anyone know what chip bicycle flashers use?  They're 1.5v, blink AND
>> have
>> on/off.  Must be billions of the buggers made...
>
> I don't think I've ever seen one that ran off 1.5V; most use several
> cells.  In fact, I might add "improved batteries" to the list of thing
> leading to the demise of the 3909 - even the smallest, cheapest (thing
> trade show giveaway) blinky things throw in extra batteries.
> When you can go to a web site and buy a couple lithium batteries,
> several LEDs, a COB IC to drive them, and some magnets to hold them
> somewhere, all for less than $2 in ones; why would anyone use a 3909?
>
> BillW


The light I'm talking about usually have a single AA or AAA battery, and
drive 2 or 3 red LEDs.  Along with the chip, there's usually a transistor
& a capacitor.

The badges etc probably use the same chip.  Similiar to the 3909, but has
on/off via a pushbutton.  COB is a bit beyond me, I'm afraid.  There
doesn't appear to be one with this functionality in 'regular person'
packaging.

If it's cheap, simple & available, why not use it?

Tony

2005\08\04@051323 by Jinx

face picon face
> Anyone know what chip bicycle flashers use?

I've a couple of Vistalite VL-300. These have 3 LEDs
in parallel and run off 2 x AA alkalines. The circuit looks
to be a simple 2-transistor multivibrator. 6 x R, 2 x C,
2 x TR + (1 x TR / 1 x R / pushbutton) for mode (flash,
steady, off)

2005\08\04@082803 by Spehro Pefhany

picon face
At 01:32 AM 8/4/2005 -0700, you wrote:
>On Aug 4, 2005, at 1:14 AM, Tony Smith wrote:
>
>>Anyone know what chip bicycle flashers use?  They're 1.5v, blink AND have
>>on/off.  Must be billions of the buggers made...
>
>I don't think I've ever seen one that ran off 1.5V; most use several
>cells.  In fact, I might add "improved batteries" to the list of thing
>leading to the demise of the 3909 - even the smallest, cheapest (thing
>trade show giveaway) blinky things throw in extra batteries.
>When you can go to a web site and buy a couple lithium batteries,
>several LEDs, a COB IC to drive them, and some magnets to hold them
>somewhere, all for less than $2 in ones; why would anyone use a 3909?
>
>BillW

Yes, the one I just bought uses 2 AAA cells. They probably use a cheap CMOS
COB chip designed for the task (not even a low-end COB micro). I have not
yet taken it apart.

Another issue is that LED forward voltages have been climbing and the
LM3909 won't handle white, blue or some green LEDs. It's obsolete for good
reason.

The blinking Logitech mouse packages used two AA alkaline Duracells powering
a COB CMOS circuit that has two resistors (one to set the flash frequency
and one to set the super-bright LED current). The RC oscillator uses an
on-chip capacitor in the 20pF range and an external 1M resistor. Flash
duration to period ratio is fixed. This device creates an eye-catchingly
bright flash to attract shoppers to the product.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
.....speffKILLspamspam.....interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


2005\08\04@085720 by onard Gabrielson

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why dont you buy one and open it up?

----- Original Message -----
From: "Spehro Pefhany" <EraseMEspeffspam_OUTspamTakeThisOuTinterlog.com>
To: "Microcontroller discussion list - Public." <piclistspamspam_OUTmit.edu>
Sent: Thursday, August 04, 2005 5:34 AM
Subject: Re: [EE] A replacement for the LM3909?


> At 01:32 AM 8/4/2005 -0700, you wrote:
> >On Aug 4, 2005, at 1:14 AM, Tony Smith wrote:
> >
> >>Anyone know what chip bicycle flashers use?  They're 1.5v, blink AND
have
{Quote hidden}

CMOS
> COB chip designed for the task (not even a low-end COB micro). I have not
> yet taken it apart.
>
> Another issue is that LED forward voltages have been climbing and the
> LM3909 won't handle white, blue or some green LEDs. It's obsolete for good
> reason.
>
> The blinking Logitech mouse packages used two AA alkaline Duracells
powering
> a COB CMOS circuit that has two resistors (one to set the flash frequency
> and one to set the super-bright LED current). The RC oscillator uses an
> on-chip capacitor in the 20pF range and an external 1M resistor. Flash
> duration to period ratio is fixed. This device creates an eye-catchingly
> bright flash to attract shoppers to the product.
>
> >Best regards,
>
> Spehro Pefhany --"it's the network..."            "The Journey is the
reward"
> @spam@speffKILLspamspaminterlog.com             Info for manufacturers:
http://www.trexon.com
> Embedded software/hardware/analog  Info for designers:
http://www.speff.com
> ->> Inexpensive test equipment & parts
http://search.ebay.com/_W0QQsassZspeff
>
>
> --

2005\08\04@122650 by Matthew Miller

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Hi Russell,

On Thu, Aug 04, 2005 at 12:58:53PM +1200, Russell McMahon wrote:
{Quote hidden}

Thanks for the circuit. It seems perfect for breadboarding and experimenting
with! In my previous message I discounted the idea of using a PIC, a 12F629
for instance, as a replacement but the responses made me think that it might
just work and use less current to boot. Such a circuit would require more
components than a LM3909 circuit would, but still a very interesting idea.

Thanks for all the good replies everyone.

Matthew

--
Zero tolerance equals zero intelligence

2005\08\04@125637 by Dave Lag

picon face
The M34 has been mentioned on another list,
UK only? COB in a real package?

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010&CTL_CAT_CODE=30405&STK_PROD_CODE=M34523

D

Spehro Pefhany wrote:
{Quote hidden}

2005\08\04@131430 by Spehro Pefhany

picon face
At 12:58 PM 8/4/2005 -0400, you wrote:
>The M34 has been mentioned on another list,
>UK only? COB in a real package?
>
>http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010&CTL_CAT_CODE=30405&STK_PROD_CODE=M34523
>
>D

Just guessing, but that maybe looks like the flasher chip that is inside
"flashing" LEDs packaged into a TO-92.

It probably has a 50% duty cycle, and is designed for different
applications (battery life would be miserable if it draws an average
of 12mA).

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
KILLspamspeffKILLspamspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


2005\08\04@184540 by Russell McMahon

face
flavicon
face
> Another issue is that LED forward voltages have been climbing and
> the
> LM3909 won't handle white, blue or some green LEDs. It's obsolete
> for good
> reason.

The 2 transistor circuit that I posted yesterday will handle any
available single LED forward voltage due to it's inductive flyback
action. I note that eg Luxeon are mounting multiple LED's per "LED"
and are in some cases placing them in series. It may handle these too,
although when you get to higher power levels the cost rises and a more
modern 1 cell LED driver is probably a reasonable choice.

Any processor that will run on the desired voltage plus one transistor
and an inductor will meet the requirement.

If manual startup is acceptable such an arrangement can self power the
processor from the flyback voltage and allow eg a 3v processor to
operate on eg 0.8v supply. Total parts count could be as low as LED,
processor, 1 x transistor, 1 x R, 1 x D, 2 x C, Inductor, battery.



           RM

2005\08\04@213220 by Tony Smith

picon face
I have!  I saw a little black blob in the middle.  Even if I scraped that
off I doubt I'd find a part number.  I'm a little surprised there isn't a
successor to the 3909 (that the rest of us can use, not just major
manufacturers).  Sometimes you just want a blinky light (trains, kites,
etc), a uP is overkill, and you couldn't be bothered figuring out the 555
RC values.

Tony


> why dont you buy one and open it up?
>
> {Original Message removed}

2005\08\04@215552 by Spehro Pefhany

picon face
At 11:33 AM 8/5/2005 +1000, you wrote:
>I have!  I saw a little black blob in the middle.  Even if I scraped that
>off I doubt I'd find a part number.

Maybe with a good microscope and good chemical removal of the epoxy blob.
But the manufacturer is probably Asian and relatively unknown.

>  I'm a little surprised there isn't a
>successor to the 3909 (that the rest of us can use, not just major
>manufacturers).  Sometimes you just want a blinky light (trains, kites,
>etc), a uP is overkill, and you couldn't be bothered figuring out the 555
>RC values.

Doesn't sound like a very big market. ;-)

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
RemoveMEspeffTakeThisOuTspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


2005\08\04@221342 by Antonio L. Benci

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part 1 2585 bytes content-type:text/plain; charset=ISO-8859-1; format=flowed (decoded 7bit)

I've used the PIC10F200T-I/OT as a cheap and chearful LED "Flasher
(TM)". The only addition being a CAP and small signal MOSFET for higher
current switching.

Nino.

Tony Smith wrote:

{Quote hidden}

>>{Original Message removed}
part 2 433 bytes content-type:text/x-vcard; charset=utf-8; name=nino.benci.vcf
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fn:Antonio L. Benci
n:Benci;Antonio L.
org:Monash University;School of Physics & Materials Engineering
adr:;;Clayton Campus;Monash University;VIC;3800;Australia
email;internet:spamBeGonenino.bencispamBeGonespamspme.monash.edu.au
title:Professional Officer
tel;work:+613 9905 3649
tel;fax:+613 9905 3637
tel;cell:+613414924833
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url:http://www.spme.monash.edu.au
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