You might be quite familiar with colorful LED strobe lights, and should have seen them pretty commonly in parties and discotheques.
Let's see how we can make one such circuit at home using LEDs. Although these devices use laser light a for the generation of the required strobe effect, using high bright LEDs can also be a good alternative, if many of are included.
Here we discuss a very simple yet very effective LED strobe light circuit which is in fact more innovative than its commercial counterparts as it produces a chasing effect to lights while implementing the strobing flashing effect simultaneously.
Circuit Description:
The proposed LED strobe light circuit is highly innovative and versatile, it actually can be used in many different applications, like in toys, decoration items, as party lights, and in avionics for displaying warning signals from the airplane (tail light probably).
The circuit utilizes the popular IC 4017 for generating the basic chasing or sequencing output through its outputs.
However the above chasing effect becomes a very primary application of the IC and here we are not looking for just a chasing effect, rather we are interested in the strobing pattern which is induced in the circuit by forcing the outputs of the 4017 IC to flash or blink rapidly as it sequences the lights.
To make the IC output strobe, we introduce another IC 4049 and integrate it to the LEDs in the circuit.
The IC 4049 basically consists of 6 NOT gate. Here two of them are used and configured as an oscillator.
Two of the gates are used buffers for facilitating better grounding effect to the LEDs, while the remaining two are used as another oscillator for driving the IC 4017 clock input.
The strobing oscillator and the clocking oscillator can be varied discretely through the respective pots for creating user defined intriguing LED strobe effects.
The LEDs common cathode termination is not connected to its usual position, i.e. to the ground; rather it’s connected to the output of the buffer NOT gates.
The oscillator from the 4049 IC transmits; rapid high and low logic pulses to the buffers which carry forward the response to the LED cathode.
When the buffer out is high the LEDs remain shut off during that instant. However the moment the buffer outputs go low, the LEDs light up and flash rapidly while sequencing, as the LED cathodes now find the ground path through the buffer low output.
The following figure shows the complete LED strobe light circuit diagram with chasing effect enhanced with a synchronized flashing effect.
Circuit Schematic
Pierre Fourie says
Hi Swagatam, do you perhaps have a pcb layout handy for this circuit?
Swagatam says
Hi Pierre, I'll to update it soon, thanks for posting
Mindy Rawlings says
Can you show a circuit it so that the LEDs have two separate sets – one clear that strobes and the other colored that is sound reactive to music connected to a speaker
Swagatam says
you can try the first circuit from this article:
https://homemade-circuits.com/2012/03/how-to-make-simple-vu-meter-circuit-at.html
It'll provide the music reactive option….for the strobing effect you can extract a separate string of LEDs from one of the red LED channels.
Jayanath Ranasinghe says
yes sir i understood. thank you.
Jayanath Ranasinghe says
ok sir here is the link,
https://docs.google.com/file/d/0B8Qj-AOXys6pZEpKWlQyeHJXdU0/edit
Swagatam says
it's perfect but the uppermost resistor is not right, it should come in series with the first LED, just as you have done with the second, third and fourth LEDs, the common anodes of the LEDs should directly join with the positive supply
Swagatam says
….sorry, correction: the common free ends of the resistors must join directly with the positive supply.
Jayanath Ranasinghe says
https://docs.google.com/file/d/0B8Qj-AOXys6pMDB4VVBrcE1wUU0/edit
see the drawing sir
Swagatam says
It's not opening, make the "share" option "public" for everyone to view.
Jayanath Ranasinghe says
ok when load is connect with positive and collector , what will be the connection of N2 side? I mean it will remain open? N2 is now connected to LED negative side.
Swagatam says
N2 output will also need to be connected with another TIP122,
base to N2 output via 1K resistor.
all emitters of the 4017 TIP122 will now join together with N2 TIP122 collector.
emitter of N2 TIP122 will connect with ground.
Jayanath Ranasinghe says
dear sir circuit is working well problem was with 4017 IC. i want to add 4 nos 3w leds. can i do with H1061 or D313 instead of TIP 122? i can choose relevant resistors.
Swagatam says
D313 is only 1amp rated, TI122 is 5amp, so only the latter will work
Jayanath Ranasinghe says
4093 pin 7 to ground and pin 14 to positive to be connected isnt it sir?
Swagatam says
yes that's right…
Jayanath Ranasinghe says
I made this circuit with 0.47= 474k 400v and 2.2M pots my circuit is not working?
Swagatam says
explain what is exactly happening….
Jayanath Ranasinghe says
ok i understood sir….. but 3W LED red green blue and white are having different voltages how can i handle this with above sir?
Swagatam says
use different resistors as per the calculations for the LEDs
R = supply – LED(V) divided by current (0.9amps)
Jayanath Ranasinghe says
not understood sir, emitter to 4017, collector to LED, base ground with 1k?
Swagatam says
bases to 4017 outputs through 1K resistors
emitters to ground
load between collector and positive
Jayanath Ranasinghe says
dear sir i made this circuit it works fine. how can i connect 4 nos 3Watt (red,green.blue white) LEDs they are having different voltages.
Swagatam says
dear Jayanath, connect TIP122 with the selected outputs of the 4017 IC and then connect the LEDs across collector/positive of the transistors with individual resistors.
The base of each TIP122 transistors should also have its own resistors (1k will do)
Jayanath Ranasinghe says
Dear sir in the circuit description it is written as IC 4049 and in the diagram IC is 4093 and the IC pin 11 is not connected?
Swagatam says
Dear Jayanath, 4049 will also work, but 4093 is the one we want in the circuit to be…so please ignore 4049. pin11 is an unused (open) output
Leonardo Glielmo says
Hi, I learn a lot with this site .Thank´s. so i got a idea of project to use in airsoft and paintball games. Is a flashbang using high power led´s. When you activate a trigger there is a delay of 5 or 10 seconds and a group of 7 or 10 high power led´s (3w) starting in a high frequency. Based in a 18650 battery . Can you help me ?
Swagatam says
Hi, Thanks!
I can surely help you, can you please provide a more detailed info about the requirement, in terms of LED placement, triggering mode etc.
I couldn't get the application very clearly.
tgoodpaster says
Happy to see the old CMOS chips still being used
Tim
Swagatam says
these will probably never die:)
Jonas says
I am interested in making this circuit, but it appears that the link to the diagram is broken.
Swagatam says
OK, check it out now…..
Jonas says
Great, Thanks! I was wondering if it is possible to use all of the output pins on the 4017 so more sets of LED could be used. Also, could 12 V LED light strips be used instead of 4 individual LEDs?
Swagatam says
Yes you may use all the 10 IC outputs for enhancing the effects. If you want to use LED strips then you will have to put transistors for handling the extra load…the IC outputs can handle only upto 10mA max, not enough for more than 4 LEDs.
Jonas says
What transistor should I use? I want to cut up 12V led strips so the maximum draw per transistor/output would be <100mA. There does not seem to be transistors with 12V BE and and 12V CE.
Swagatam says
It will be an elaborate design, cannot be explained here. I'll draw it and post it soon…..
under18_yun says
i have a same question like jonas. What transistor should i use to powered up my led strips.
Swagatam says
you can use BC547 transistors with 10k base resistors.
under18_yun says
hopefully u can shared the design here. so we can share it to the others.
Swagatam says
i's simple just do following changes:
replace the 100 ohms with 1k resistors, and connect the bases of the transistors (BC547) with these resistors.
connect the emitters to ground or negative.
connect diodes (anodes) to the bases of the transistors and connect all the free anode ends of the diodes to N2 output.
Now connect LEds with individual resistors to the collectors of the transistors. Done!
Swagatam says
correction: connect all free cathode ends of the diodes with N2.
Mohd Asrul Dor Baser says
I would like to change to push button instead of using the VR to change the effect of led. Can u help me to build it because i am not expert in electronic
Anonymous says
I am interested in making this circuit but the link to the diagram appears to be broken.
Joe says
I actually want the LEDs to blink in a design I make and then be able to flip a switch and have it act like a color organ.
joe says
instead of having them chasing is there a way to "flip a switch" or install one to make them all blink at the same time?