A Simple yet Effective LED Strobe Light Circuit Explained

You might be quite familiar with strobe lights and should have seen them pretty commonly in parties and discotheques. Although these devices use laser lighta 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 effect simultaneously.

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Circuit Description:

The 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.