The article explains a simple random LED flasher circuit which can eb used fo decorating Chrstmas trees or other similar items during festivals.
How the Circuit Functions
I have already discussed a few interesting applications of the IC 4060 as an oscillator for driving clock input ICs like 4017 and also as a timer for producing variable time delays, ranging from a few seconds to many hours.
The oscillator function of the IC can also be effectively employed for driving colorful LEDs and for creating interesting LED light show. The idea can be used for illuminating vehicles, houses and typically Christmas trees during Christmas.
As discussed in one of my previous articles regarding the use of the IC as an oscillator, here the IC is set up as an oscillator for generating the required oscillations or clock signals at the different outputs.
Since the IC is able to generate clock signals or square waves through all its outputs, every output from the IC can be effectively used for displaying interesting LED light flashing with different rates of frequency.
The oscillations generated at the outputs of the IC increment with multiples of two or in other words they just double with their frequency across all the outputs at a specified pin out order.
Therefore some pin out LEDs may flash at very high rates while some may flash at very slow rates while still other may flash at intermediate rates, each LED chain having its own specific flashing rate.
The entire light show presented by the configuration thus creates an intriguing effect which can be very eye-catching.
The figure shows rather simple wiring where the IC itself acts as an oscillator as well as the LED driver.
Each of its output is wired into a string of colorful LEDs which may be set up or arranged in any desired format for acquiring the most interesting lighting effects.
The pot may be used for optimizing the flashing of the LEDs to the desired levels or at the rate which might suit the particular decorative application the most.
The circuit should be operated with voltages above 12 or precisely speaking, the applied voltage should be ideally fixed at 15 volts (regulated).
This typically high voltage enables many LEDs to be connected across each input, four to five LEDs to be exact.
Since so many LEDs are involved the power rating the transformer needs to be at least 500 mA.
The whole circuit may be enclosed inside a plastic box with strings of LEDs terminating out of the box so that they may attached to any desired structure like the Christmas tree.
Hi Swagatam,
The above circuit shows 4 LEDs in series directly driven by the 4060 IC. Is this correct? Will the 4060 drive 4 LEDs in series without an external transistor? If they are Blue LEDs, what will be the current flowing through the 4060 with the 330R current limiting resistor (assuming a supply of 15V as your diagram shows)?I looked at an LED current limiting resistor calculator and it appears that the current of each LED would be 8ma. Will they be bright enough with only 8ma? I’m working on a project to flash 3 to four LEDs (depending on the color) in series from each output of the 4060 and I am using 12v supply. This circuit is very simple, but maybe I should consider transistors to get the power to drive the LEDs brightly. Your thoughts? Thanks!
Hi Norman, yes it will be bright enough for a 20 mA LED. Also, you can reduce the resistor values to 220 ohm to increase the brightness a little more.
If you want dazzling brightness then probably you may have to use an external transistor stage.
Can we increase the no.of led to 50 each
you will need transistor driver stages for that, on each channel.