Introduction: DIY Portable LED Strobe

Picture of DIY Portable LED Strobe
I and my friends like to have fun in summer. We like to fool around with music when we are camping. To make those parties more likely to professional ones I have made portable 9V LED strobe. For my surprise it really gives a big effect. I hope you will like it!

Lights! Camera! Action!

Step 1: Tools

Picture of Tools

Here is the list of tools you will (mostly) need:
5)knife (or wood carving knife)
6)1, 3, 6 and 7mm drill bits;
7)drill stand or dremel tool;
8)sanding paper;
9)solder or soldering station;
10)lead solder;

Step 2: Schematic and PCB

Picture of Schematic and PCB

This project is very simple but there isn't as much schematics on the internet as I thought it will be. But I'm happy because I found this one. It is really simple and cheap. All the parts (including the case) can be found at local radioshack just for a few dollars. And what is really cool that it can be done in one day!
The heart of this schematic is timer LM555. It generates square impulses which width is regulated by variable resistor or potentiometer (it really doesn't mater which will be used).
Light board can be made from as many LEDs as you want. Starting from 3 LEDs and increasing by 3 (for example it can be 3, 6, 9, 12. 15 and etc.). I have chosen 60 LEDs for brighter light
I have uploaded my schematic and PCB in Eagle and .pdf formats. My main board is really small. You can make it smaller if you use SMD parts but it's necessary. LED board is 87x57mm size (perfectly fits into my case).

Step 3: Parts

Picture of Parts

Bill of materials (BOM) for electronics can be found in .txt file that I have attached. All those parts will cost just few dollars. Maybe LEDs will cost more.

Of course you will need some parts for case assembly such as:
1)8xM3 screws;
2)two small screws for switch mounting;
3)4x10mm metal holder;
4)4x22mm metal holder;
5)case (I have used plastic 90x60x25mm).

Also there is 9V battery holder, some wire, DC jack, switch and variable resistor knob (I have shortened it because original was to long).

Step 4: Assembly

Picture of Assembly

I forgot to take pictures of soldering part. But I think it is easy to understand from schematic and board layouts because there are just a few parts.
How you can see, I have connected switch just to battery holder. When switch is off but DC adapter is connected it still works.
Now when it is done with electronics it's time for casing!

Step 5: Casing

Picture of Casing

How you can see there were no holes and fittings in my case so I had to make them.
To hold case, LED's board and organic glass in place together I have made 3mm holes for screws and those metal holders. 10mm holders were used between organic glass and LED's PCB. And those 22mm length were used inside case for holding all the parts together.

Step 6: Finishing

Picture of Finishing

While finishing the strobe I thought about LED's board. I should have painted it black or even chrome. But well I have made mistake which you can avoid. It still looks nice and shiny. That organic glass really does the job. It protects LEDs from scratching.
By the way. Power supply can be from 6 to 12 volts. I use 12V indoors. It flashes brighter. And for outdoors I use 9V battery which really easily fits in case. I am happy about this my project, it really works well.

P.S. If you decide to use bigger casing you can use Joulie thief to make LEDs flash brighter from battery.
P.S.S. If you want to make color light strobe you can use RGB LEDs or cut out various colors films and clip them to the organic glass.

I hope You enjoyed my first instructable!


AmrE60 (author)2016-12-28

thanks for the file

HardlyHumanFX (author)2016-09-22

Is it possible to flash the LED 80 times per second with this circuit? Thanks!

I think, it's possible.

jd72cv11 (author)2014-11-06

This is a nice little project! Thanks for posting it.

Some thoughts on the circuit...

A pull down resistor on the FET gate is always recommended. Floating gates/grids are not a good thing :-)

Also, and this is just being nit-picky, one resistor to limit the current for all of those diode strings is not 'best practice.' In your application it's not much of an issue because you are using a 9V battery. But if someone was to use a DC power supply and a diode string were to fail, other strings could start cascading and lead to a fiery mess. I'd have to recommend a resistor per diode string.

ryork5 (author)2013-11-25

Awesome job mate! :)
How about, if we want to string 2 LED strobe (right - left) with a different variable blink .. thks ..

DOT. (author)ryork52013-11-27

If I understand correctly, you want to make double strobe light, like those Police lights, yes? If so, then write me here or privately, I will make another instructable ;)

ryork5 (author)DOT.2013-12-01

yes, you are right .. can you make me right scheme? pleassee .... :)

Ronny_the_king (author)ryork52013-12-18

Give the guy a break, not everyone has got plenty of time on their hands.. Why don't you just search for it here on instructables or on google.. If you did you would have found this one:

ryork5 (author)Ronny_the_king2013-12-19

thank you, but I want a blink of strobo like this video :

ryork5 (author)DOT.2013-12-04

heii DOT,, can you help me, make a stobe like i mean ??

DOT. (author)ryork52013-12-04

I will make it, but you will have to wait a little bit. It takes some time :)

ryork5 (author)DOT.2013-12-15

heii DOT,, What has not been completed?

DOT. (author)ryork52013-12-15

I will share the instructable when it will be finished

ryork5 (author)DOT.2013-12-15

okayy,, thkss

ryork5 (author)DOT.2013-12-04

okay, I'm ready to wait.. thks DOT :*

gh0st85 (author)2013-11-29

I have 2 ledstrips of both 12-24V, they actually already light up at 9V and didn't test them with higher voltages than 12V. Is it possible to connect these in parallel and what can I do to allow higher voltages to pass through?

DOT. (author)gh0st852013-11-29

You can connect those two LED strips in parallel. I have checked 555 timer datasheet and max power supply voltage for it is 16V. So 12 volts is the best.

dozer789 (author)2013-08-20

This is pretty cool!! Congrats on winning the contest!! I like to make things with electronics so I am going to have to try making this!!

DOT. (author)dozer7892013-08-21

Thanks! It's really nice that you like my instructable! Write me if you make one too. I would like to see how it will look :)

dozer789 (author)DOT.2013-09-05

It would be a little before I would make one of these because I am very busy right now, but if I do ever make one, I will write you!

Ploopy (author)2013-09-04


Where does pin 4 of the 555 go to? positive? nothing?

DOT. (author)Ploopy2013-09-04

Thanks! Pin 4 isn't connected

Neil Quinny (author)2013-08-16

hey dot im sorry for confusing you, i wanted the labeling part in pdf so i can print it and a logo of your name so i could print tht as well Thanks A Milli

DOT. (author)Neil Quinny2013-08-16

Hey! Everything is ok, it's nice to help you :)
Do you mean part layout like this?

Neil Quinny (author)2013-08-10

hey DOT. could you please send the schematic in adobe pdf format, i do not have the eagle software. Would it work with a 23 half watt LEDs on a 9v battery??? Thank You for yhe Awsum project.

DOT. (author)Neil Quinny2013-08-13

Hey there! I have uploaded schematics in pdf in the second step, near the other schematics.
I think it won't work, because 9V battery won't be able to drive so much power ot it will work shortly.

244 Jake (author)2013-08-11

Hi Dot,

The flash will work great, as you know. I have four like it but with all IR, LED's. I built mine about 7 yeas back, for night photos of wild life. Placed the flash units to create lighted area, single flash has a hot spots. I used a PIR to fire up the camera and only noise was the click, with not hint of the flash.

There is a difference in doing things perfectly, per manufactures / engineering guide lines, and just getting a job done, using what works, moving on to the next project.

Ya done good!

244 Jake

DOT. (author)244 Jake2013-08-13

Hey! I think those photos made at night with IR flashlight look great. I would like to see them!
Thanks! It's nice to hear that you liked my project :)

nancyjohns (author)2013-08-12

Hey, my 9v battery flashlight didn't make it through so now I'm rooting for you!:)

DOT. (author)nancyjohns2013-08-13

Hey! I hope you will succeed this time :)

mračickas (author)2013-07-29

Awesome job mate! ;)

DOT. (author)mračickas2013-07-30

Thanks dude!:D

rbahr (author)2013-07-25

Any reason the cathodes and anodes of the 2nd led of a 3 part series are all connected to each other?

I believe that you would want to have all the LEDs in series, with only the topmost and bottom-most LED connected to a common source/gnd. You should also use a current limiting resistor, unless the foward voltage is significant enough to limit the current. Variance in manufacturing will cause different LEDs to consume more current as the forward voltage (vf) varies. To my knowledge, the way you have it now could cause some of the LEDs to fail prematurely from over current if their vf varied considerably. Considering you vary the voltages between 9-12, the effect could be more profound at 12V. This is ok within a hobby project, but also a quick fix if you just add resistors and remove those common nodes. I'm not sure of the vf of the LEDs you chose. If you wanted to have more fun, you could attempt to do a PWM (generally 10% duty cycle at 1KHz) LED Strobe, which can net you 10x more current on some LEDs and get a brighter strobe.

switch62 (author)rbahr2013-07-29

You can't have all the LEDs in series.  Each white LED needs about 3V across it @ 20mA.  60 LEDs in series needs 180V to make them light up. You won't get that from this circuit and 9V battery.

In the current circuit each row of 20 LEDs are wired in parallel, which form (electrically) one "super" LED which runs at 3V @ 400mA.  The 3 rows are then wired in series, so you need 9V @ 400mA for all 60 LEDs to light.

If you redraw the LED schematic as below, you can see what I mean.

Any difference in Vf of any LED will not affect it's current enough to shorten it's life.  There is also a 5.6 ohm resistor to limit the total current in the circuit.  About 536mA with 12V, that's about 27mA through each LED.  Close to the maximum of 30mA, but since it's not continuous (flashing) there should be no problem. ( I'd probably increase the resistor to around 7 ohms just to be safe.)

Placing lots of resistors to limit the current of each LED will cause unnecessary complexity and wasted power through heating of the resistors. 

rbahr (author)switch622013-07-29

My description was a little poor, but he stated he was going up in LED size by 3 LEDs and it had to be a multiple of 3. His current circuit would be affected by going multiples of 3 as you would have to recalculate the current and adjust the main resistor accordingly to hope you limit the current appropriately. My statement was meant to set up 3 LED in series, and then do multiples of those in parallel. So instead of having "super" leds of 400 mA vf=3V, you actually have a more manageable 30 mA vf=9V led. There is no reason to advantage to connect them into 400 mA vf=3V sets and put 3 of those in series. I never meant to imply putting all 60 LEDs in series, just sets of 3.

Right now there is one issue with 3 sets of "super" LEDs of 400 mA. The assumption is that between all the LEDs, in this case 20, that the forward voltage is off by no more than 10% at most for any given LED in a parallel LED array (currently for the calculations you generated, though granted, it will not be operating at 100%).

The LED of each "super" LED with the lowest vF will consume the most current, possibly significantly as the IV curve is exponential. With the current wiring, you are guaranteed to have the most current flow between the LED with the lowest VF of each "super" LED array, and have a current path that is much higher along those 3 LEDs (the lowest vf of each super LED).

If you have 3 LEDs in series, and then put those in parallel, at the very least you would have some variance. There is a better chance that the 3 LEDs with the lowest vF will not be in series together, and thus overall averaging out to a better chance that you will not have significantly higher current consumption between any setup of 3 LED (that are in series) that are parallel with additional multiples of 3xLEDs.

In all honesty, the smartest and most reliable thing to do is to put 3 LEDs and a single resistor for the appropriate voltage drop in series. You could then put as many of those in parallel and the entire project would scale to any size so long as your power source could handle it. The power dissipated in the resistor would be minimal, and I don't believe it would actually be much worse than a single 2W 5 ohm resistor with .53 Amps going through it. In theory I believe that both circuits would dissipate the same amount of power through a resistor, just that you would have additional resistors and actually limit the current to each LED string to its rated specs, whereas now it is unpredictable. If you wanted to limit the current of my proposed 3xLED in series in parallel with additional strains, you would have about .03A going though 20x resistors, which would also be about .6A, and you could have 5 ohm resistors to each one. The only single downside is that you have physically more resistors, but the advantage is that you have predictable current to each LED, prevent thermal runaway, and increase the longevity of the LEDs. The cost of higher power rated resistor vs several smaller resistors isn't one of issue compared to the cost of a few LEDs.

Please refer to this:

switch62 (author)rbahr2013-07-29

I agree that the most reliable thing to do is as you describe.

The question is how close are the Vf /If curves of all the LEDs.  I can't find any data on the manufacturing variations, only typical curves.  I would assume that manufacturing tolerances are very small for LEDs, and the extra current in a low Vf LED would only amount to 1-2mA at most.

Even for 3 LEDs and a resistor, the current will vary due to the sum of all the Vf.  In fact the current for a single LED & resistor setup will still have a low Vf  LED draw more current, as the resistor value is based on the average Vf from a data sheet.  (To be truly accurate and reliable you need a constant current source, but that's going too far.) 

The main issue is over heating of the LED which causes it's demise.  You'll see data sheets quote 30mA continuous Maximum, but 100mA peak for pulsed operation.  I think in this application of a strobe, any LEDs with low Vf will be fine.

DOT. (author)switch622013-07-29

You said just what I wanted to say just didn't know how to explain that well in english :D Thanks!

DOT. (author)rbahr2013-07-29

If you look in the schematic you will see that there is one 2W resistor for all LEDs. They are all connected like this to act it like one powerfull LED which are driven by LM555 through IRFZ44N which maintains that evry single LED flashes the same. And how I mentioned in my instructable LM555 works as PWM because it generates rectangular impulses which width is controlled by variable resistor (I checked that with oscilloscope). Yes, of course it works brighter from 12V because it gets more volts. But none of my LEDs burned down.

rbahr (author)DOT.2013-07-29

Yeah I didn't verify if you were doing PWM in the sense that the actual pulses are of a very low frequency (<200 HZ) of constant current for the flashing or if you did PWM of around 1KHz of a certain duty cycle in addition to the original strobe for increased brightness, but in order to do the latter I believe you would need 2 timing devices, one for the PWM of the dutycycle/brightness of the LED, and another one to regulate the on state which corresponds the frequency of the flashes.

Tin Man (author)2013-07-26

Make a smaller version for hill-walking emergencies?
A larger one with a smooth magnetic base to go on the car roof in case of break-down?

DOT. (author)Tin Man2013-07-29

Cool idea. It can be made with SMD parts and then you will be able bo put main board and LEDs in flashlight housing

StuNutt (author)2013-07-25

Great Idea!

But I'd like to see a diode in series with the battery, If you have a DC supply plugged in and have accidentally left the battery switch in the "on" position, you'd be pumping current INTO the PP3 battery - definitely not a good idea and could cause a "catastrophic event"!

But I'm thinking of making one that displays the name of our volunteer emergency group, to place on top of the car when stationary at an incident/event.

(so if you see a car with RAYNET flashing on the roof, it could well be me!)

DOT. (author)StuNutt2013-07-25

That is great idea about diode! You are right about that "catastrophic event". I think, I will add this protection to my strobe.
If you are really going to make one, which you will place on top of the car, you can use neodymium magnets. They are really strong and they won't scratch your cars paint.

StuNutt (author)DOT.2013-07-26

In UK, there are many restrictions on the types and colours of lights that we can put on the top (or anywhere else!) of cars, so it could not be in use while moving.

Our emergency group usually make ourselves and our vehicles conspicuous (apart from looking like a porcupine with the antennas!) mostly so that runners/ walkers/ etc can spot the control point where we can pass emergency messages, call for medical support and so on.

Having said that, much of our activity is by using charity runs, fairs and suchlike in support of Red Cross or others as "practice for the real thing", and in the case of the "real thing" I think I'd probably use any means available to make my car stand out if "getting there quickly" could impact safety of life.

Might do that with the magnets - I already have 2 antennas (VHF/UHF) on the roof on magnetic mounts.

DOT. (author)StuNutt2013-07-29

I understand that well, because in Lithuania there are many resctriction too on types and colors of lights that can be mounted on cars. But well, I hope you will think how to mount those lights in your car to let people know that you are in a hurry.

bricabracwizard (author)DOT.2013-07-28

Good instructable! You could also connect up a switch to your DC input so that when you put in the plug it disconnects the battery.

DOT. (author)bricabracwizard2013-07-29

Thanks! I was making just portable strobe but then I have found one unused DC jack. I was thinking about three position wsitch or two switches (one for battery and other for DC) but I didn't want to change switch which was already mounted in the box.

Project 23 (author)2013-07-29

DOT. (author)Project 232013-07-29

This is very nice! I was thinking about what changes shoud be done in Instructables app

ariekaptein (author)2013-07-25

Why do you use flux on a pcb? It's basicly an etchant and agressive as hell to electronic components; better use resin core solder wire.
Also be carefull with spraying chrome paint on a pcb; the paint contains metallic perticles which can short-circuit components.
But; a real nice strobe!

About This Instructable




Bio: I am a student in electronics. It's not only my hobby but a style of life. As my other big love is art, I ... More »
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