Making a PWM Based LED Strobe Light Effect Generator Circuit

The inquiry  for making a LED Strobe light circuit was sent to me by one of the keen readers of this blog, regarding the making of an IC 555 based LED strobe light effect generator circuit, let's learn the whole issue.

The Circuit Request

Thanks for this guide, I went by my local radio shack and picked up most of these components...Two
things I was not able to acquire was a 1m pot (all they had was a giant
sized pot in the 1m rating) and a 100k resistor (they were out)

I picked up a 4 pack of 22k resistors and wired them in series which gave me 88k which again is close.

I also picked up two 100k pots which i hoped could prove useful.

Knowing full well I don't have the recommended materials on the list I got an effect which didn't much resemble a strobe.

Using the 100k pot there is some variance in the flash speed but it isn't really slow to really fast.

Also my led never goes all the way out using this, again possibly my fault for having the wrong components.

Circuit Objective

What I would like: the ability to strobe a LED three or 4 sharp fast pulses with a pause between bursts

What will the difference between 88k ohms and 100k ohms in the resistor be visually?
I assume a 1m pot will give a much wider range of speed adjustment.

To get pulses with the led do I need an oscillator? with another pot?

Thanks in advance!

Solving the Circuit Objective

Thanks for replying.

I think the above circuit is not very suitable for obtaining strobe light effects, because it is not designed for generating differentiated mark and space ratios.

Your requirement of making the pulses pause for a moment in between sharp pulses would require a PWM kind of design with the IC 555.

A conventional type of PWM generator using a IC 555 is shown below and can be hopefully used for your type of application.

Here the pot can be used of discretely adjusting the mark/space ratio of the output pulses which in turn helps to optimize the output for obtaining the intended sharp pulses and pauses, this dimensioned output ultimately produces the required strobe effects with the connected LEDs.


11 thoughts on “Making a PWM Based LED Strobe Light Effect Generator Circuit

  1. Have questions? Please feel free to post them through comments! Comments will be moderated and solved ASAP.
  2. Hi Swagatam
    I wish to build a strobe circuit using the 555 and 2 white LEDs.
    I want the LEDs to strobe seperately.
    I also wish to control the duration and frequency of the bursts.
    Can you please give me a schematic?

    • Hi Max,

      You can try the above circuit, the strobe rate can be varied by adjusting the pot as desired.

      For separate strobing you would have to make two of these circuits

      Use this formula for calculating the LED series resistor.

      Supply voltage minus LED FWD voltage divided by LED current.

      Here the current should be taken as 150mA or 0.15A.

      For one LED per output, the FWD would be 3.3V

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