Tiny circut to blink a light??

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Johnnycrash
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Tiny circut to blink a light??

Post by Johnnycrash » Wed Jan 25, 2017 2:14 pm

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.
John Fleming
I know that's not what the instructions say, but the kit's wrong anyway.

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Richard Baker
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Post by Richard Baker » Wed Jan 25, 2017 4:11 pm

This site has flashing LEDs on different types- no circuit needed-
http://www.modeltrainsoftware.com/ledlights1.html
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tetsujin
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Post by tetsujin » Wed Jan 25, 2017 5:56 pm

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Raven PCB project (a bit outdated)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.
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Johnnycrash
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Joined: Fri Jul 12, 2002 12:57 pm
Location: Timmins, Ontario, Canada

Post by Johnnycrash » Wed Jan 25, 2017 7:37 pm

Thanks guys. The blinky LED seems to be the choice. Now I need to find an itty-bitty switch to go with it.
John Fleming
I know that's not what the instructions say, but the kit's wrong anyway.

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