Introduction: LFTT (LED Flashie Throwie Thingie)

Picture of LFTT (LED Flashie Throwie Thingie)
You may already know the LED throwies

The LED Throwies are very cool, however they could be a little more attention getting with just 2 extra components.

This Instructable will show you how to make a flashing LED Throwie.

Step 1: Parts List

Picture of Parts List

To make one LED flashie you'll need:

a 10mm LED (I recommend, that you use a diffuse LED. I live in Denmark and the diffuse LEDs aren't available here, so I just used a waterclear type)

a CR2032 lithium coincell battery.

a Neodymium (NdFeB) disc magnet.

a LM3909 LED Flasher circuit

an Electrolytic capacitor (the bigger the capacitor is, the slower the LED flashes. I figured out, that a 100µF works fine. It will flash the LED at approx. 2.5Hz, while a 220µF will flash it with 1Hz.

Step 2: Solder the Capacitor Onto the LM3909

Picture of Solder the Capacitor Onto the LM3909

Now it's time to Solder the capacitor onto the LM3909 (see all the pictures)

Step 3: Solder the LED Onto the LM3909

Picture of Solder the LED Onto the LM3909

Now it's time to solder the LED onto the LM3909 (see pictures)

Step 4: Cut Off the Unused Leads of the LM3909

Picture of Cut Off the Unused Leads of the LM3909

Cut off the unused leads of the LM3909, so they don't short circuit.

Step 5: Solder Two Leads Onto the LM3909

Picture of Solder Two Leads Onto the LM3909

Now it's time to Solder two leads onto pin 4 and 5 of the LM3909.

Step 6: Mold It (optional)

Picture of Mold It (optional)

You can "mold" the circuit using a hot glue gun. This will make it water proof and shock resistant.

Step 7: Tape the Battery and the Magnet Onto the Circuit

Picture of Tape the Battery and the Magnet Onto the Circuit

Tape the battery and the magnet onto the circuit, just like you would do with an ordinary LED Throwie

Step 8: Throw It!

Picture of Throw It!

It's time to throw your LED flashie


zs1apb (author)2009-04-30

Hi there. LM3909 IC's have been obsolete for at least the last 10 years :-(( Anyone know of a cheap source for these? Regards. Tony

yukthi (author)zs1apb2011-05-20

yes its true !!!

Are they? I just got them from my local electronics supplier.

Hi there. Only picked up your reply now :-(  Apologies!! Would appreciate you finding out how many LM3909 IC's your local supplier has and at what cost.
These chips have been unobtainable her in South Africa for the last 7 years :-(((  Thanks and regards.

robot1398 (author)2011-03-25

i agree with catman0321
here is a instructable

catman0321 (author)2010-10-08

you can just sand the led down with sandpaper

agis68 (author)2009-07-20

for anyone who needs forgotten LM3909!!! I found in a store here in Athens some boxes containing thousands of this IC, so anyone who wants some of them are available!!! costs 0,80 each

zs1apb (author)agis682010-05-09

Hi  there. Are these still available? If so what is the cost and how much to post to South Africa? Thanks and regards. Tony

agis68 (author)zs1apb2010-05-12

 I have to check  it first

porryman (author)2010-04-06

How much time should the batterie be alive??? I've made the same circuit and the first batterie ruined out in 1 week. I used a 100 µf / 25v capacitor and a ordinary red led diode.
I've read the lm3909 datasheet and with a 1,5 v AA batterie it should be working for at least 6 month.
What could be wrong??

Thank you very much in advance

3unchi (author)2009-11-13

Hehehe video sounds like Pentax :D

LOL. As a matter of fact, it is actually a Pentax. Do you own one yourself?

Speeddemonrs (author)2009-10-16

Wow, how much radiation does that thing put out?!?!? In the video, it sounds like the geiger counter is going CrAzY!! lol!  Neat idea!

LOL. That's just my old camera trying to focus. It has noisy optics.

albylovesscience (author)2009-09-29

more like led sezure throwie just kidding

willymakesstuff (author)2009-05-27

WHAT PINS!!!!!!!!!

Move your mouse over the pictures to find out.

buteomont (author)2009-05-11

You are only 14 years old, and can make better instructables than many adults. Keep it up, you'll make a lot of money one day!

I certainly hope so. Thanks. Actually I'm 15 now.

samphantom (author)2008-06-23

Hello there This is interesting but I do not know if you know, but there are in the market built in flashing LED and the cost of those are very cheap, the bad thing is I believe they comes in red and yellow but for the instance u can add this flashing leds in series to another color LED you want. You can find them in Digikey online. But is good though.

Thanks. I know there are some LEDs with a build-in flashing circuit but: 1. The flashing 10mm LEDs aren't available in diffused version 2. With this you can control the flashrate by changing a capacitor 3. The flashing LEDs aren't available where I live and I'm not old enough to buy stuff from the Internet in other countries.

You can diffuse an led by sanding it with sand paper. My mom is from Denmark so I visit there a lot and speak danish fluently.

Coodude26 (author)2008-11-04

Can't you but LEDS with blinking modules built-in?

Coodude26 (author)Coodude262008-11-04

oh sorry nm

Sandisk1duo (author)2008-10-22

blinking LED?

Curious seb (author)2008-09-10

What componnent you use to make it and where are you buy it. how long is working with one battery.

The components you'll need are here. I got my parts at a local electronic parts store. I actually haven't tried how long the battery will last, but I guess, it would be around a week.

samphantom (author)2008-06-24

Hello my friend. Keep the good track line with your invents, the less I want to do is to take you out of this precious career. Some times is difficult to find components in other areas but still you can order this items sometimes for free in some online sites (e.g. But do not worries it will came the day that you can buy your own items. I did not looking for 10mm flashing diffused leds but I'm sure there will be. Anyways thank you for your comments and if there is anything that is on my hands to help you let me know.

Hey, thank you very much.
When I'm 15 years old (in less than one year), I may get my own paypal account, so I can buy stuff from the web =).

And thank you for offering your help.

darkbain (author)2008-06-22

Ha, did that happen

darkbain (author)2008-06-14

I like this indestructible, it's well illustrated. Blinker circuits (especially for throwies) never get old. Thanks for posting.

Mattrox (author)darkbain2008-06-20

dontcha mEAN instructable

assasin090 (author)2008-05-26

whats a throwie?

Take a look at this

Artificial Intelligence (author)2008-05-25

Actually, I don't know much about computer games, because I don't play them. Why don't you make a forum topic about this instead of posting it in an Instructable.

therian (author)2008-05-12

using chip for such task is overdue, 2 transistor audio oscillator will do the job and parts can be salvage from anything

I know, that you could do this with a astable multivibrator, but if you did that, the throwie would have to be bigger.

maybe I just too cheep but I love to salvage parts , the feeling of making something from "nothing "

I know what you mean, I salvage parts too. Three times a year, there is a big market nearby me where they sell used and new stuff: clothing, electronics, cups dishes and stuff like that. I often buy some cheap electronics there.

carrothead23 (author)2008-05-11

tis is da beeeeeeeeeeeeeeeeeeeeessssssssssst!!!!! :) :) :) :) :) :) ;)

Artificial Intelligence (author)2008-05-02

It's okay, I admit that I hot glued sloppy. He didn't said: wow you really suck at hot gluing stuff.

joejoerowley (author)2008-04-19

Cool! Great Instructable!
One suggestions is to upload your video to youtube, metacafe or someother site like that so that you don't have to download it to watch it. Other than great idea.
Also you can get LEDs with the blinking circuit built in here.

you're right, 10mm flashing LEDs are available, but not the diffused types. and with this circuit you can adjust the flash rate by changing the capacitor

I sure you can get them somewhere with diffused. If not it is not that hard to make an LED diffused.

Ward_Nox (author)joejoerowley2008-04-19

couldn't u diffuse a water clear using superfine grit sand paper?

joejoerowley (author)Ward_Nox2008-04-19

yeah, or a dab of hot glue.

Tried both these things, but unfortunately non of them really works.

Oh, thats to bad. Ping Pong balls work pretty well too.

killerjackalope (author)2008-04-19

well joe already mentioned flashing leds that are premade, I like the idea, you could probably recollect these and replace the battery when possible to recover the cost of the extra components, they look sturdy enough and also the setup would allow handy battery removal...

About This Instructable




Bio: Hi all, I'm a college student in the copenhagen technical college. I'm currently working with 3D printers and I'm building my own ...
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