Re: Flasher for dog collar

Hi, there's an lm3909 equivalent circuit here using (iirc) 4
transistors and a handful of other parts.

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


With SMD skills and a PCB routing program you could possibly build a
very small single layer PCB which would be almost the same size as the
LM3909 and include the LED and (tantalum SMD) capacitor.

:)

-Also the NTE876 is listed as a replacement.

Another idea (if you don't mind having to use a higher supply voltage)
is to use one of the PIC12C series parts and a 32kHz watch crystal with
the watchdog timer set to a 1 second flash.

-A

greysky wrote:
Hi-

I need to build some sort of a flasher to put on my dog's collar- she's the
same color as the carpet and keeps getting stepped on :-) I'm thinking a
3909 flasher running a LED from a coin cell. I haven't kept up to date on
what's available, or if there are any better chips than the LM 3909 out
there. Ideally it should be able to run for a year and be small enough to be
clipped onto the dogs collar without having a honking big battery hanging
off it (ideally the thing has to be smaller than the dog, which is pretty
tiny). Any suggestions appreciated. TIA.

.