How to Make Any Light a Strobe Light Using Just Two Transistors

If you feel strobe lights very interesting but are disappointed by the fact that these wonderful light effects can be produced only through complex xenon tube then probably you are quite mistaken.

It is very much possible to make any light a strobe light if you are equipped with a proper driving circuit capable of handling different lighting devices to generate the desired strobe light effect.

The present article shows how a circuit as basic as a multivibrator may be modified in different ways and made compatible with ordinary bulbs, lasers, LEDs to produce spectacular light pulses.

A strobe light may be used for warning, scientific analysis or as an entertainment device, whatever may be the application the effects are simply dazzling. In fact it is possible to make any light a strobe light through a proper driving circuit. Explained with Circuit Diagrams.

Difference Between Flashing and Strobing


A light when made to blink or flash indeed looks pretty eye-catching and that’s the reason why they are used in number of places as a warning device or for decorations.

However a strobe light in particular may also be considered a flashing light yet is uniquely different from ordinary light flashers. Unlike them in a strobe light the ON/OFF pattern is so optimized that it produces sharp dazzling pulsed flashes of light.
There’s no doubt why they are mostly used in conjunction with fast music to enhance a party mood. Nowadays green lasers are being popularly used as a strobing device in party halls and gatherings and have become hot favorite among the new generation.
Whether it’s LEDs, lasers or an ordinary filament bulb, all can be made to flash or rather strobe using an electronic circuit capable of producing the required pulsed switching in the connected lighting element. Here we will see how we can make any light a strobe light using a simple electronic circuit.

The following section will acquaint you with the circuit details. Let’s go through it.

Pulsating any Light to Produce Strobing Effect


Through one of my previous articles we came across a nice little circuit able to produce interesting strobe effects over a few of the connected LEDs.

But this circuit is only suitable for driving low power LEDs and thus cannot be applied to illuminate big areas and premises.

The proposed circuit allows you to drive not only LEDs but also powerful lighting agents like incandescent bulbs, lasers, CFLs etc.

The first diagram shows the most basic form of a multivibrator circuit using transistors as the main active components. The connected LEDs can be made to strobe by suitably adjusting the two potentiometers VR1 and VR2.

Strobe Light Using Just Two Transistors and two LEDs

The above circuit forms the base for all the following circuits through some suitable modifications and additions.

Using a Flashlight Lamp as Strobe Light


For example if you want to illuminate and pulsate a small torch bulb using it, you would just need to do the simple modifications as shown in the second diagram.

Here by adding a PNP power transistor and triggering it through the collector of T2, a torch bulb is easily made to strobe. Off course, optimum effect is achieved only through proper adjustment of the two Pots.

Strobe Light Using using motorcycle bulb

As already discussed already in the previous section, green laser pointers are pretty popular nowadays; the diagram illustrated shows a simple method of converting the above circuit into a pulsating green laser pointer strobe light.

Here, T3 and T4 form a typical current controlled transistor configuration – a must when vulnerable lasers are involved.

The selection of R6 can be critical and will decide the current limiting threshold for a safe operating of the laser.

A wrong calculation may instantly roast your costly laser bulb.

The following formula may be used for calculating R6:

U = 0.6/Ilaser,

Where U = Operating voltage of the laser and the circuit.

I (laser) = Maximum safe operating current of the laser device.

Strobe Light Using Just laser pointer


Using AC 220V or 120V Lamp as Strobe Light


The next diagram shows how an AC mains lamp may be used as a strobing light source using the above circuit. Here a triac forms the main switching component receiving the required gate pulses from T2’s collector.

Strobe Light Using triac and high power halogen bulb

Thus we see that through the above circuit designs it becomes very easy to make any light a strobe light simply by doing the relevant modifications within a simple transistor based circuit as exlained in the above examples.

Parts List


R1, R4, R5 = 680 Ohms,

R2, R3 = 10K

VR1, VR2 = 100K pot

T1, T2 = BC547,

T3, T4 = BC557

C1, C2 = 10uF/25V

Triac = BT136

LEDs = as per choice

Need Help? Please send your queries through Comments for quick replies! And please Bookmark my site :)




Comments

Jimmy Gillman said…
I got a few questions for you. I am a volunteer fireman and I'm thinking about using your design here for some emergency lighting for my jeep. How could i wire in 2 strips of LEDs both containing 6 LEDs, and make them alternate? Also can this circuit work on a 12v DC circuit?
If you can email me about this I'm very interested in learning more.
Swagatam said…
The above circuit will work with 12V supply.

You can use the first circuit with the following mods:

Connect LED on the other arm also but use three LED in the series.

You can accommodate another series of 3 on each arm with separate individual series resistors as done with the previous series, in this way you have six LEDs on each side.

If you have readymade strips with the above series built in, you can simply connect each strip directly between the collector and the positive of the transistor on each arm..R1 and R4 will not be required in that case.

he parts list would be:

R1, R4(for the first option) = 150 ohms
R2, R3 = 68K (the VR1/2 are not required, you can remove them and connect R2 R3 directly with the positive rail)
Capacitors = 10uF/25V

Transistors = BC547
Jason Stein said…
I'm an amateur with dc electrical circuits but quite fascinated and eager to try. I have been throwing around the idea of trying to build an electric fence charger. I think your strobe circuit would work. Would you agree? I need a constant on/off/on/off power source capable of delivering a high voltage shock while still not being strong enough to deliver permanent damage. These are the specs on a 2 mile fence charger.

Item Specifications:
115 volt, 60 cycle
AC input/output
0.5 joule output
Pulsed output
Output voltage no load is 2300 volts
2 mile range

I would like to build a tiny fence charger that would energize only about 50 ft. What do you think...is it possible?
Swagatam said…
Yes the above circuit can be used with a fence charger for triggering short pulses, I have discussed one similar application which employs a 555IC producing identical results which also has an adjustable pulse rate feature, you can refer to the following two articles for getting an idea regarding the concepts:

https://homemade-circuits.com/2012/05/make-this-solar-powered-fence-charger.html

https://homemade-circuits.com/2011/12/homemade-fence-charger-energizer.html
Swagatam said…
....for making it tiny you can replace the ignition coil suggested in the above links with a small ferrite core transformer as used in mosquito zappers.
Swagatam said…
Hi, the third circuit would perfectly suit your need. LS1 may be replaced with the LED,
T4 = 2N2907
T3 = TIP32
R6 = 0.6/0.5 = 1.2 ohm it's the current limit for limiting the current to 500mA
rest everything would be as per the given parts list.
Swagatam said…
....T1, T2 = 2N2222
Adam Cullen said…
Hi, I followed your first circuit diagram on a breadboard and it worked perfectly. I'm truing to make a 12v circuit using 12 festoon LEDs with inbuilt resistors. I can't quite work out from your written description what to do. Can you draw it?
Swagatam said…
Hi, if the LEDs are rated to work with 12V, you may connect 6 of them in parallel across each transistor collector arm, they should work, but the transistor may need an upgradation and may be replaced with 8050
Adam Cullen said…
Hi Swagtam, OK, getting closer. My previous post probably didn't accurately describe what I'm trying to do. I have a vehicle 12v festoon LED bulb that I want to rapidly blink. I originally didn't understand what you meant by connecting between collector and positive (I thought you meant the positive base of the transistor, and blew it up) but understand now that you meant the positive rail at the top of the circuit.

OK, so I have removed R1 and R4. R2 and R3 are still the original 10k ohm resistor and the trim pots are still there at 100k ohm. I wired in the 12v LEDs where the original 3v LEDs are in the 1st circuit. Now I get the LEDs to light up, and dim slightly with a tweak of on of the trim pots, but no blink.

Should I take out R2 and R3? Should they be replaced with a smaller ohm resistor? One last piece of info is that the 12v festoon LEDs measure 88.7 ohms across.

Any help would be appreciated.

Adam
Swagatam said…
Adam, yes making R2/R3 smaller will produce faster blinking rates so you can try replacing them with 1k resistors.

If the LEDs are not completely shutting off, the reason could be leaky caps or wrongly connected cap polarity.

If the caps are OK, you may try adding a series 50 ohm resistor with the LEDs to eliminate the issue or put 1N4007 diodes in series with the emitters of T1/T2
shahid qureshi said…
Hello

Just came across your blog. Are these circuits free to use or there are any copyright issues???
Swagatam said…
Hello, Practical use is free and allowed, but publishing elsewhere could be an infringement
Mukesh said…
Thanks and it worked great..how to make them to blink twice one and twice other if we connecting them on other arm as you said above in comment?
Swagatam said…
For blinking it twice on each channel you may have to build another identical circuit, but without the collector resistors.

connect the collectors at the junction of the respective resistor and LED of the on each channel of the previous circuit.

adjust the new circuit to blink faster so that two blinks are injected on the LeDs.
Swagatam said…
...make sure the resistor of the LED is connected with the positive and the LED with the collector for implementing the above integration.

if you have the LED connected to positive and resistor to the collector, just swap the positions.
Mukesh said…
Hey i tried 1st one and works perfect on 9v battery and if i connect them in my bike the bc547 gets heated and no blinking in bulbs..
Mukesh said…
Please give a suggestion..
Swagatam said…
use 1k for R1, R4 and if possible replace the BC547 transistors with 2N2222....
Mukesh said…
Hey bro when i connected this circuit the led is not blinking instead glowing steady also bc547 gets heated much
Mukesh said…
What should i do?also is it ok to replace the two led with led strip?
Swagatam said…
led strips rated to work on 12V can be connected with the above circuit, change the transistors and check again, it seems the transistors are blown, replace them with 2N2222 or 8050
Mukesh said…
Yeah u r ryt it blown out...now works perfect as per ur diagram but brightness is low wt to do for it?i hv replaced two led and 680ohms into led strip..whats advantage of 2n2222 and 8050?how to check blown transistor? Btwn thnkz a lot finally my bike blinking:-)
Swagatam said…
LED strips already have internal resistors so may be R1, R4 can be eliminated from the circuit.

2N2222 or 8050 are have higher current rating will not become warm or get damaged with higher current or voltages.
Swagatam said…
.....2N2222 or 8050 have higher current rating therefore will not become warm or get damaged with higher current or voltages.
Mukesh said…
R1too it won't affect ics?btwn does it is reduce the brightness of the led due to less current? I already removed r4.. Does it works on 24v circuit too? Thnkz for the kind reply :-)
Swagatam said…
sorry No, if you are using only the R4 channel then you should NOT remove R1 otherwise T1 will blow off.

yes you can 24V also but only if the strips are also rated at 24V
Mukesh said…
Cool super works by u :-) can u lend me ur email id i have some queries and i need to send pics?
Swagatam said…
thanks Bro! here's my email ID hitman2008@live.in
Jason Anderson said…
I'm interested in flashing an LED 80-100 times per second. How can I accomplish this? Thank you!! jasona111988@gmail.com
Swagatam said…
reduce C1/C2 and VR1/VR2 values...
Michael Weidner said…
I've noticed that some strobe circuits are better than others. Better, I mean sharper transient response. I'm looking at the kind used in the strobascope applications. https://en.wikipedia.org/wiki/Stroboscope

I've created art using this concept and tried various strobes. The conventual novelty units work best, cell phone stobe apps do not. They seem to blur the visuals the conventual are crisp.

Can you tell me why and also point me in the direction of concept to make a working circuit with sharper transient response?

Thanks!
Swagatam said…
Did you try a simple PWM IC 555 based stroboscope circuit? or you can also try a NAND gate PWM circuit for generating absolutely sharp turn ON/OFF strobe effects
Swagatam said…
the pulse width can be controlled through the shown pot, and the frequency by changing the capacitor values.
tony gomes said…
Hi! i´m try to use this for an OFF/ROAD led cubes in my vehicle andmanage to make it work eleminating "R4" but still the leds do not illuminate to their maximun capacity and sometimes they stop being strobes, these led cubes are 12v but do not specifies the watts, Iknow they are hig wattage, could you please help me with this dilemma? thanks in advance

I use 1/2w resistance
Swagatam said…
Please try the second circuit from top, replace the bulb with your LED, but make sure to add a calculated resistor in series otherwise your LED and the PNP transistor both might get damaged

you can also try the third circuit from top
Swagatam said…
T3 should be TIP127 or as per the LED current
tony gomes said…
HI, finally I know that the LED cubes are 12v 18w and i´m going to use two LED cubes, if I use the second circuit with the "TIP127" is going to work?
Swagatam said…
Hi, yes you can use the second circuit for getting the intended results.
Swagatam said…
use a large heatsink for TIP127
Yakub Gangrekar said…
Hii sir, I am interested in using your circuit for speed measurement( Application of Stroboscope) so will it work for flashing light at high frequency and provide sharp light pulses at variable rate I.e at 0.5 ms to 100 ms? Please It'll be so kind if u can help me...
Swagatam said…
Hi Yakub, yes it will definitely work...you can try the second design from top....make sure to connect a 1N4007 diode in series with the emitter of the PNP transistor to ensure total switch OFF of the connected lamp
Anshuman Parmar said…
Hi Sir, I am a begginer in this and don't even know about the symbols or short forms of parts used in the schematic diagram. So, please kindly help me in this. I am interested in making a simple Led strobe with simple parts. So plz sir kindly send me circuit diagram with full names of parts and their values. Bcoz i can't understand above circuits of strobe lights.I will be very thankful to you for helping me.
Swagatam said…
Hi Anshuman, here's the parts list for you

Parts List

RESISTORS, 1/4 WATT

R1, R4, R5 = 680 Ohms,

R2, R3 = 10K

POTENTIOMETER

VR1, VR2 = 100K pot


TRANSISTORS
T1, T2 = BC547,

T3, T4 = BC557

CAPACITORS (ELECTROLYTIC)

C1, C2 = 10uF/25V

Triac = BT136

LEDs = as per choice
Paul said…
Hello,

Which of this circuit well power 12v LED to use as signal blinker for a motorcycle? And as replacement for my broken flasher in my motorcycle?
Thanks..

Paul
Swag said…
you can use the second circuit for your purpose, replace the bulb with your 12 LED connections
Paul said…
Thank you very for the quick response
Thank you for helping us newbies..

Paul
Paul said…
BTW Sir,

In the second circuit can i add a piezo buzzer? And can i remove the two leds connected at R4?

Thanks again.
Paul
Swag said…
you are welcome Paul!
Swag said…
yes you can remove the LeDs, and also add a buzzer in parallel with R1 or R4...the buzzer should be a piezo buzzer ready to use
Paul said…
Sir,

I have successfully built the 2nd circuit i it works but how can i make it blink slower and i have set the VR2 in maximum and its still blinking fast. Do i have to increase the 100k pot? thanks..

Paul
Swag said…
Paul, increase the two capacitors values proportionately, that will slow down the blinking rate....
Paul said…
Sir can i replace VR1 with a fixed resistor and can you suggest what values of resistor can i replace..
Thank you..

Paul
Swag said…
you can directly connect R3/R2 ends with the positive line, but make sure these are at least 22K
Wesley Burchnall said…
Does anyone have a good place to get the parts in order to make this? Also, approximately how much would the parts to make this cost? I was thinking more of the 120V version. The 120V version would allow me to take a bank of LEDs that is connected to 120V plug I plug into the wall...and in theory if I plug it into this circuit then this device into the wall, would cause that bank of LEDs to flash rather than be on steady, right?
Swag said…
Hi Wesley, In India the cost of the parts would be less than a dollar, not sure about other countries. Yes the last circuit would allow you to illuminate lamps specified to work with 120V AC

You can buy the parts from any online electronic spare parts store, although the shipping charges could be 20 times higher than the actual cost of the parts
nitin chaudhari said…
Hello sir, can I use this strobe light circuit as a pwm for small dc motor ???
Swag said…
Hi Nitin, yes you can use, try the second design.
nitin chaudhari said…
Hello sir, I want know why two pot are used?
Can use one fixed and one pot instead???
Swag said…
You can use one pot in the manner shown here:

https://www.homemade-circuits.com/make-this-electronic-mosquito-repeller/
nitin chaudhari said…
Hello sir, I cant get a 100k pot in our local market. I got a rotary switch having six fixed similar resistors (switch used in small emergency led light pack as dimmer). Can I use this switch as a pot buy replacing all six resistor with 15k resistor (each step will increased by 15k ohm as switch rotate) for above circuit???
Swag said…
Hello Nitin, you can use the pot or the rotary switch with 15K resistors, both will work.

Contact me for Customized Circuits

Name

Email *

Message *


 Follow on G+  Follow on Facebook   Follow on Tweeter  Follow on G+  Follow on G+

Follow Homemade Circuits