Instructables
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I made this as a quick project I made to use a lot of the LEDs I recently got. It basically connects via a 555 8 pin IC and allows for adjusting the time between the flashings by changing the resistor or capacitor values. It provides for a cool looking effect in a dark room. Use your favorite color LEDs and enjoy!

 
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Step 1: Gather the parts

Picture of Gather the parts
Okay, so let's beign.
Here is what you will need:

1 - Timer 555 8 pin IC
1 - 2N3905 PNP general switching transistor
1 - 2N3053 NPN general purpose amplifier (I dont know if this is a switching or amplifer but I used MPSA2222A instead and it worked fine, I also tried 2N3904 and it worked, but a littler worse than the one I used)

20 - red LEDs (although you can use any color choice you want)
20 - blue LEDs (although you can use any color choice you want)
1 - LED (this is used to verify if your circuit works, can be any color)

1 - 1uF Electrolytic capacitor
1 - .1uF disc capacitor

1 - 150k resistor
1 - 4.7k resistor
1 - 160 ohm resistor
1 - 220 ohm resistor (although I used a 160 ohm)
20 - 100 ohm resistors (I didnt have 20 so I used 10 of 100 ohm and 10 of 120 ohm)

1 - 6V source
wire
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chirag19964 months ago

i dont want switching between red and blue i want combine flickering of 41 leds what can i do

plz.. tell

chirag19964 months ago

can i use 6v dc output transformer

Nikhil Kedia5 months ago

http://dangerousprototypes.com/2013/01/06/app-note-digital-potentiometer-analog-applications/

SHAHROZALI1 year ago
Hello sir i m very interested in learning electronics works so please tell me about my questions my second question is how can check a 555 I.C With multi Meter???
I dont know if you would be able to read the pulses of a 555 ic using a multimeter. But if you have acess to an oscilloscope you more than likely would be able to see the pulses on it. I have never done such a thing, but Im sure its likely.
J-Five1 year ago
That's a lot of LED's!!!
A video would be nice.
I want help on this, i have a project to build for 200 flashing LEDs and i need help on circuit diagram and the type of parts needed. please my email is isholamoses@gmail.com any help will be greatly appreciated
SHAHROZALI1 year ago
HELLO i shall wait your questions and i want to make to flasher circuit with 555 I.C
SHAHROZALI1 year ago
HELLO SIR MY QUESTION IS HOW CAN CHECK TO NPN TRANSISTOR AND PNP TRANSISTOR?AND WHERE IS CONNECT OHM AT TRANSISTOR?
vince261 year ago
if i wanted 5 set of leds to flash simotaniously instead of 2 what all would need done?
Bulantuy2 years ago
CAN I USE LM 555 CN BY NATIONAL INSTEAD OF NE 555
Yes, they are the same thing.
scottinnh3 years ago
Supes,

Could this be modified to not do flashing at all, or to flash at such a quick rate that it is not visible flicker? (I'm assuming that removing the flash altogether would be hard on the batteries, if they even can supply enough current.)

I'd like to just run this many batteries off AAs without requiring a million resistors, or losing 1/3 the energy as dissipation through the resistors.
If your flash rate is too fast they will come on but be very dim. You can make this work very easily without flashing involved. For a beginner i would suggest finding a different diagram to follow rather than trying to figure out what components to remove. (IC, Caps, extra resistors, even possibly the transistors (depending on Ea - Applied Voltage).
where is the negative side of the battery??? i cant see it
The negative side of the battery is everywhere you see the
_
- ofcourse there are three little lines but everyone of those should be connected to ground or in this case the negative (-) side of battery
MROHM3 years ago
Excellent Instructable!!!!!!!!! 41 LED Flasher is Awesome,,,,,,Yee-Ha!!
MROHM3 years ago
Hi! Just a Suggestion Here,,,,I built this little baby and noticed one thing,,after leaving this circuit on i noticed the transistors were getting warm especially the 2N3053 (Max Ic of 600 M.A.) To Alleviate the Problem I subbed 2N3053 for Tip31(Power transistor,,,Ic of 3 amps) and 2N2905 for TIP41 (Power Transistor Ic of 3 amps) 2 advantages here,,,,, 1) Transistors will remain cooler here. 2) you will be able to add a pile of extra Led's to this circuit and the Tip's should be able to Handle the extra loads.. This is still a really Good Instructable,, but If we can improve the circuit why Not??!!?? We might be able to double or even triple the Led output and the TIP's should be able to take it!!! Supes this is a SUPER INSTRUCTABLE!!!
hummvee34 years ago
I bought everything needed to build this but i have a problem understanding how to read a schematic and the photo does not show where all wires go. if any one has built this please email me some photos to hummvee3@yahoo.com it would be much appriciated. i would really like to make this and this is my fisrt time making a circuit of any type and i like the idea. please help with photos that shows where to place wires on the bread board. thanks again
I know what you mean. A lot of diagrams are made for people who already know electronics.

The simpler ones show (+) & (-) wires so us novices can follow them. This diagram has many different ground symbols when I believe it's where the (-) lead goes.
MROHM rcisneros3 years ago
You are right on this one my Friend!!! My only advice to you is to build or breadboard Simpler Circuits and once you feel comfortable you can move on to more complex ones. I have been in electronics a long long time and enjoy simple circuits over complex circuits,,,,because;;; 1) They work~~~~100% of the time and 2) they are easier and faster to construct, 3) you can build your knowledge faster so you can tackle the tougher circuits at a later date!!! Good Luck and Happy Building!!! I must go now,,,, I smell my Weller!!!!
did anyone ever send you anything to help on your problem? If so can you send it to me I am trying this for a project and just cant seem to figure it out.. benny_resendez@yahoo.com
the ground is negative. the leade on the transistor that has the arrow is the emitter, the center one is the base, and the other one is the collector. all l.e.d.'s are polarized. if you look at the two leads one will be longer than the other. the shortest lead is negative. thats basically all what a novice wouldnt know. go to bluedashlight.webs.com to see my modified schematic for 12-14 volts.
it does show where all wires go you just need to use jumper wires to connect things. the schematic does not show wher wires go but what they connect to just draw it out trust me i built this and like from 6 to 2 just use a jumper wire either over the ic or around it. it is easier if you use a breadboard for this.
nice
mased0073 years ago
So cheap LEDs. I live in Slovakia and I bought 1LED=0,50€
kctess53 years ago
if you don't have a pnp transistor you can always just add more leds on the same circuit with the npn transistor with some minor changes
scottinnh3 years ago
The project inspiration URL is now http://www.bowdenshobbycircuits.info/ (not http://ourworld.compuserve.com/homepages/Bill_Bowden).

I'd actually never seen that site before, so I got 2x value from reading this instructable. Thanks!
PLEASE I HAVE BOUGHT 5 TIMES THE PARTS AND THEY DONT WORK.... PLEASE TELL ME ALL THE PARTS AGAIN BECAUSE I CANT FIND SOME OF THEM IN MULTISIM.....
markee23 years ago
i have a   

similar flasher circuit but the rate of flashes is variable 

the difference is it has a potentiometer taken from
http://electronician.blogspot.com/2010/11/led-flasher-circuit-using-555-ic.html


simple 555 led flasher.jpg555 led flasher schematic.jpg
bfaridnia4 years ago
Got it to work but now I notice the stand that is connected to2n3053 is way dimmer than the other stand. I played with the resistor between the transistor and the 3 pinout but nothing worked. Can someone explain this to me? I think it had to do with forward voltage at the high output being less that at the low. But not sure how to correct. Thanks
*strand
Complex124 years ago
Hey, your supplies list a 2N3905, but the picture of the schematic you have uploaded shows a 2N2905 in use.

Please clarify.

Thanks!
bfaridnia4 years ago
Connected everything and the led lights but doesn't flickr. I replaced the 150k r with a 1 meg pot and still nothing. There is a noticeable haze of a flickr. Not sure what's going wrong. Could I try a 10mfd capacitor instead of the.1? Any one else have same problem.
bfaridnia4 years ago
Connected everything and the led lights but doesn't flickr. I replaced the 150k r with a 1 meg pot and still nothing. There is a noticeable haze of a flickr. Not sure what's going wrong. Could I try a 10mfd capacitor instead of the.1? Any one else have same problem.
geeklord5 years ago
so do PNP's stop conducting when there is a current at the base?
positve negative postive negative is the base and since the timer output is + - + - it turns on and off with the positve and negative votage. its like you quickly switch the red a black wire on the battery it would go + then when u switch it becomes - make sense? basically the 555 switches th polarity for you at a specific rate.
hai geeklord... the the transistor is said to be in on state ,only when it gets a forward bias across its base and emitter....the polarity configuration depends up on the type of transistor .. NPN or PNP...
supes (author)  geeklord5 years ago
the radio shack 555 should work...
geeklord supes5 years ago
K, just wanted to make sure that radio shack wasn't doing what they do best!
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