Post by thread:[EE]: LM3909 LED Flasher Obsolete?

I have been told by a local distributor that the LM3909 LED Flasher has been declared as obsolete some years ago. Does anyone know of a modern day equivalent of this device? Regretfully a PIC12C508 doesn't qualify for my application. Regards John -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

At 12:59 PM 10/10/01 +0200, you wrote: >I have been told by a local distributor that the LM3909 LED Flasher has >been declared as obsolete some years ago. Does anyone know of a modern >day equivalent of this device? Regretfully a PIC12C508 doesn't qualify >for my application. No. If you have the voltage available maybe you could use a CMOS 555 etc. The flashers on Logitec mouse boxes use a COB CMOS chip that runs on 3V. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" spam_OUTspeffTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com /.-.\ (( * )) \\ // Please help if you can: \\\ dailynews.yahoo.com/fc/US/Emergency_Information/ //\\\ /// \\\ \/ \/ -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Thanks Spehro Ideally I'd like to run from a single alkaline cell, the LM3909 was so ideal... oh well... Spehro Pefhany wrote: {Quote hidden}> > At 12:59 PM 10/10/01 +0200, you wrote: > >I have been told by a local distributor that the LM3909 LED Flasher has > >been declared as obsolete some years ago. Does anyone know of a modern > >day equivalent of this device? Regretfully a PIC12C508 doesn't qualify > >for my application. > > No. If you have the voltage available maybe you could use a CMOS 555 etc. > The flashers on Logitec mouse boxes use a COB CMOS chip that runs on > 3V. > > Best regards, > Spehro Pefhany --"it's the network..." "The Journey is the reward" -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

part 1 1634 bytes content-type:text/plain; (decoded 7bit) > I have been told by a local distributor that the LM3909 LED Flasher has > been declared as obsolete some years ago. Does anyone know of a modern > day equivalent of this device? Regretfully a PIC12C508 doesn't qualify > for my application. I'll post this cct again again. As shown it lights the LED apparently constantly using the following values L = 300 uH to 1 mH (resistor sized RF choke) R = 1 M C = 100 pF. R must not be able to provide enough bias current to hold load on at its max value. . Transistors are small TO92 and not critical but having Q1 rated for higher current is useful (eg BC327 is 500 mA rated). Changing R & C values will change flash time. Try increasing C at first. R must be kept biggish to maintain above required relationship. If you want more details see my post of a week or 2 ago with this cct attached or ask me offlist and I'll send you a copy. For slower flashing the inductor size may need to be upped to get more energy per flash. Unlike the LM3909 this will produce voltages of many times the input voltage so can be used for eg modern blue or white LEDs with high operating voltages. Oscillator cct is years old (with an R where L is). Addition of L was my idea but is obvious enough that it must have been done before by others. Place LED in either position shown. LED2 is more efficient but may glimmer very slightly in off mode with a new 1.5v cell and a red LED. Cct operates down to Vin = 0.8v or less. Can be used as a general purpose step up cct (swap npn and pnp and supply rails for step up). Russell McMahon part 2 1637 bytes content-type:image/gif; (decode) part 3 144 bytes -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

At 02:27 PM 10/10/01 +0200, you wrote: >Thanks Spehro > >Ideally I'd like to run from a single alkaline cell, the LM3909 was so >ideal... oh well... You can double the voltage using some switching regulators, but I'd think the second battery would be cheaper. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam@spam@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com /.-.\ (( * )) \\ // Please help if you can: \\\ dailynews.yahoo.com/fc/US/Emergency_Information/ //\\\ /// \\\ \/ \/ -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

John I am also a victem of the obsolete statement when trying to get a LM3909. I have a half dozen in constant use. One powered by a C cell has been blinking a led for over 2 years without a break. I have now been using a "Holmate Technology Corp." led driver that looks like a little plastic transistor with 3 leads. It requires two 1 1/2 volt batteries, a resistor and the led. Sell for about $1 + ship. The company is from Tiawan(sp), dealer in CA. I can't find my notes with their phone number but their fax # is 510-252-9885. You can hardly understand them on the phone anyway. They have a web site and the only way they will take orders besides fax. (Weird outfit). Try a search for Holmate. I use the CDT3258-1 led driver to flash 1 per second. They last quite awhile on the 3 volts..... ==Mac== At 12:59 PM 10/10/01 +0200, you wrote: >I have been told by a local distributor that the LM3909 LED Flasher has >been declared as obsolete some years ago. Does anyone know of a modern >day equivalent of this device? Regretfully a PIC12C508 doesn't qualify >for my application. > >Regards > >John -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.