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Infrared (IR) LED Flood Light

In this post we study a simple infra red based flood light system which can used for illuminating large landscapes during night for monitoring wide aresa through IR spectacle.

The Design

The adjoining design shows a simple IR flood light circuit diagram for IR illumination applications.The 4049 section is the basic voltage doubler circuit which effectively boosts the 9 V supply to a level of around 15 V which further becomes the supply voltage for the next 555 pulse modulator section.

The voltage is suitably pulsed as per the settings of P1 and P2 for driving the associated IR LEDs.

The main feature of this infrared IR LED flood light circuit is that it utilizes just a single PP3 9 volt battery and yet is able to provide lights (IR) at dazzling levels.

 Infra Red (IR) LED Flood Light Circuit Diagram

Infrared (IR) LED Flood Light Circuit Diagram

Need Help? Please leave a comment, I'll get back soon with a reply!


  1. Hi Simon,

    The frequency is determined by C4, making it lower increases the frequency and vice versa.

    Here's the LED specs used above:

    5mm LED
    940nm wavelength (most common)
    20 degree beam width
    20 mA continuous, 100 mA pulse
    Approx 1.6V forward voltage

    The IC 4049 is used as a voltage doubler so that more number of LEDs can be accommodated in series, while the 555 is used as a PWM controller.

    Actually the 4049 is not needed, you can simply use the 555 IC solely for the required actions, albeit you will need to remove a few LEDs from each series.

  2. Goodday Jacques,

    The circuit hasn't been built yet by me, you can use the formula given in the diagram for evaluating P1, P2.

  3. hi ya swagatam

    Do you have a parts list for this setup. . . ..I am building basic 9v Lights with 18 - 20 10mm IR Leds
    940nm, 1.2v FV 20ma and 30 deg beam

    Gotta love foolin around with gadgets lol

  4. Hi John,

    The presets can be around 10k, the remaining values are printed on the diagram, just click on the diagram to get an enlarged view and the details...

    yep, foolin around is like keep it up,

    and if you get hold of any of those creepy things do let us know how they look and what they eat...hehe..just jokin buddy

  5. lol i really dont thing they eat lol. . . . .

  6. Good evening swags...

    what is the use of p1 and p2

    can I make 14 strings of led? and what is the value of r4 in case of 14 led?

    can I use it used for night vision?

  7. Good evening Achilles
    p1 and p2 are for adjusting the intensity of the LEDs

    14 leds can be used.
    yes, it's for night vision application.

  8. hi swagatam.....
    what is p1 and p2 in the circuit?

  9. hi hashir,

    p1, p2 are variable resistances called pot or preset.

  10. good afternoon Sir!
    Can I make 3 led's in series and what resistor will I use. Then can I make them 3 led's in parallel (consisting of 3 led's in series with resistor). 9 led's all in all.

    Can you give me specific P1 P2 R1 R2 and C4? I dont know how to calculate the frequency or I dont know the purpose of those so just give me a constant values for a good night vision flashlight..

  11. eshkariel, yes you can connect 3 leds in series and more such series in parallel, in that case you wont need te 4049 voltage doubler stage, you can power the circuit directly with the 9V batt.
    you can use 470 ohms for each series.
    pi, and p2 are for adjusting the intensity of the Leds and can be adjusted as per individual preference

  12. Good afternoon Sir,
    what are the specification of the ir led? 5mm, 3mm or 1 watt?

  13. Good morning eshkariel,

    it's 5mm, 20mA

  14. HI Engr. Swagatam....
    I have a few questions...
    In what mode does the IC555 operate...

    and hey can you help me out about the circuit's theory of operation?
    cause I need this in our school....our goal is to find any circuits with digital IC....excluding IC555...and found this circuit I guess I need your help...

    btw the 555 here is ok...just need to know the mode...

    tnx alot ^_^

  15. Hi eshkariel, the mode is astable with variable PWM functionality using the shown oppositely configured diodes at its pin#7 and the pots.
    the explanation can be very lengthy, so it may not be possible here....

  16. Hi,

    I have a failed IR floodlight which used a relay to pulse power to the LEDs arranged in 22 "strings" of 7 IR LEDs, and was fed from a nominal 12 volt DC 1 Amp PSU. The LEDs are all OK, it is the "relay pulsing" circuit that has failed.

    Do you think that this circuit would be a suitable replacement for the "pulsing relay" driver if fed by 12 volts DC?


    Carl in the UK.

  17. Hi, you can modify and use the above explained design for pulsing the LEDs, relay may not be required as it can be done through a transistor stage also by configuring it with pin#3 of the IC.

  18. ..the 4049 stage can be ignored and eliminated.


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