Tiny circut to blink a light??

[Johnnycrash]

He all,

Looking for the simplest design to run 1 LED and have it blink, powered by a button battery, with an on/off switch.

And I have a VERY tight space for all the parts: 3/8" x 3/8" x 1" with the LED at the top, and switch at the bottom.

[Richard Baker]

This site has flashing LEDs on different types- no circuit needed-
http://www.modeltrainsoftware.com/ledlights1.html

[tetsujin]

With that kind of space I could (and would, honestly) use one of my microcontroller boards:

Raven PCB project (a bit outdated)

The smaller boards are in the neighborhood of 9mm x 11mm and can be cut smaller (at the expense of some I/O pins)

Disadvantages:

• You need to know how to program a microcontrollers
• A microcontroller costs a few bucks, compared to the $1-$2 maximum that a blinky circuit should cost
• You have to solder the microcontroller to the board

Advantages:

• The microcontroller is pretty much the only component you need, and soldering it to a PCB makes for a pretty robust circuit
• If you want to do anything more complicated than a fixed-rate blink, a microcontroller makes that way easier.
• If you ever change your mind about how the LED should blink, a microcontroller makes that way easier, too.

More traditional alternatives like 555 circuits and whatnot actually wind up being more complicated than a simple micro because you need more components. Resistors, capacitors, etc. With a micro the only components you really need are the microcontroller itself, and a current-limiting resistor for the LED.

Of course the easiest solution for a blinking LED, as Richard pointed out, is just to get a LED that has a blinky circuit built into it. There are a few limitations to going that route - it may limit your choice of what LEDs to use, you can't choose how fast the LED will blink or synchronize it to other LEDs - but if those limitations are OK for what you're doing, then that's a perfectly fine way to go.

[Johnnycrash]

Thanks guys. The blinky LED seems to be the choice. Now I need to find an itty-bitty switch to go with it.