Picture of simplified firefly jar
This is my first instructable so be kind please. Please also keep in mind I'm not an electronics expert. I know just enough to not know what I'm doing.

I was inspired by photozz Fireflies - Analog version. I had two 555 timers but didn't have the cd4026b IC. Instead what I had was a sn7447an IC. Even with the help of photozz I still couldn't get it to work. So I started looking for a different way. I found the simplesit LED blinking circuit on http://www.cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html (note: any metteral taken from the above site is copyrighted to Dick Cappel) From there thru trial and error I designed my simplified Fireflies in a jar circuit. We will keep it simple and only do three LED's for now. Ime working on a 10 LED jar.

Parts list.
3 2N3904 NPN Transistors (Almost any other NPN or PNP from your junk box will work)
3 various resistors (I used 2-10K and a 1-1K resistor try different combos from the junk box)
3 100 ohm resisters (this one is a must or you MIGHT blow your LED's)
3 various capasters ( used 1-2200 UF 2-470 UF one 35V and one 16V try different combos.)
3 green surface mount LED (or any other color or kind)
1 Power supply of some sort. I used a Nokia Type ACP-7U. Out put is 3.7V DC at 340 mA I'm to cheap to buy batteries, and the cell phone for this charger became a dogs chew toy.
Various wires. the thiner the better.
1 mason jar. or some other type of inclouser.

Solder gun

Optional but nice.
Universal Breadboard.
Prototype board.
I am confused.
I built this circuit to your specifications and to the original designs specs.
The LED (3v Amber) lights up to a dim glow and stays on at 12 volts and does nothing entirely at 3 to 11. I tried reversing the 2n3904s collector and emitter and the circuit doesn't function at all.
Any thoughts?
Earths_hope5 years ago
sorry, but you camera was dying in early 2007, and now its 2010! where are those upadated photos?

also, this is a coment bump

giving 4 stars
Dannos (author)  Earths_hope5 years ago
Well thanks for the bump but that project has sense been torn down and the pieces es used in other experiments.  I had so much fun doing it I might do it again and now I do have a good camera so if I do it again The picks will be there
llaven8 years ago
Thanks for sharing this idea, i try make my own, i think that simple circuit will work like a Photovore but with a little eolic supply, obviously no with Solar panel supply, with this hack we only put the jar on window open and work in the night with the wind. Romantic idea, ha? :-)
Lol with the jar open?? Wont the fire flies escape?
ampeyro5 years ago
wow, it's realy simple(the circuit), isn't it dangerous for the transistor? I'm trying to repair led flashing lights(the ones used in construction), the plan s to put another thansistor where you put the led(my leds uses 12 v and 2 amps at all) thanks
cosgrove7 years ago
Interesting Instructable, though you may wish to run it through a Spell Checker, some of the spelling was not so great
budsiskos7 years ago
can you please post a better circuit diagram
budsiskos7 years ago
how long did the blink last?
One fellow who tried to build the basic flasher circuit had problems because he tried to run it from a 9 volt transistor radio battery. I just put one together using a 2N4401 and found that with a 1k resistor, it operated from 9.1 volts to 20.7 volts. A bit higher than you should expect from a 9 volt batter. Using a 2k resistor raised the upper voltage past the 27 volt maximum output from my bench supply. I appreciate the reference to my web page. Note that my copyrighted material remains my property, even though it is posted on this site.
Dannos (author)  Dick Cappels7 years ago
Wow thanks for commenting on my little project. I am on your site all the time. You have no idea how much I have learned from your site. you should post some instructables
Taotaoba8 years ago
Nice! Look forward to you final pictures.
Dannos (author) 8 years ago
Just a little side note here. If you have a well stocked junk box the cost of this project can be 0