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led multicolor flashing globe circuit

Crazy Multicolor Flashing LED Globe!

Nowadays, single-color and multi-color flashing LEDs are easily available, which obviates the requirement of external chips to produce fascinating lighting effects. What can we do with one piece of such a single color flashing LED, and two pieces of multicolor flashing LEDs? Here is an ultrasimple circuit of an LED Globe wired around the evergreen timer chip IC 555. One advantage of this LED Globe is that it is a voltage-controllable flashing device, ready to work together with any microcontroller chip. This allows you to control the light pattern to a certain extent in tune with the output signal from an external microcontroller, too!

Schematic of the Multicolor Flashing LED Circuit

led multicolor flashing globe circuit

Nothing new, here the 555IC (IC1-LM555) is wired as a monostable multivibrator (MMV) working on regulated DC5V supply. RC components R2(1K) and C2 (100uF) sets the monotime period. At the front end of the circuit, one single-color flashing LED (LED1-5mm Red) is connected across the power rail through a current limiting resistor (R1-1K). The pulse output available from this LED is directly fed to the trigger input (pin 2) of the 555 IC. The control voltage is driven to the control voltage terminal (pin 5) of IC1 through a resistor (R4-1K). For normal use, the control voltage can be generated from a 10K multi-turn potentiometer (P1-10K) as shown in the circuit diagram. Actually, any kind of DC voltage level generator can be used to control this circuit. It could come from a photoresistor voltage divider, sound to voltage converter,from a microcontroller,etc etc. The IC1 output (from pin 3) is then extended to two 5mm multi-color flashing LEDs (LED2&LED3) through a single current limiting resistor (R3-47R).

As you may well know, 555 IC turns on when its pin 2 is below 1/3VCC, and turns off when its pin 6 goes above 2/3VCC. These levels can be shifted either higher or lower than the nominal levels by applying a voltage at its pin 5. For example if we apply a higher +ve voltage, the turn off threshold is higher than the normal 2/3VCC. This trick is used in this circuit to produce pleasing (and fairly unpredictable) light patterns from the three LEDs. Try to enclose the finished circuit in a translucent globe for better attraction. Or try an artistic arrangement with the help of suitable light diffusers!

Note

  • Set jumper J1 in open position when you are using an external control voltage
  • R2-C2 values used here is not very critical. Start your own experiments with various values
  • If you want to use multiple LEDs at the output, try to use suitable driver circuits based on bipolar transistors/mosfets
  • If you have another simple solution for achieving this effect I’d love to see it. Please use the comment box

Test Report

  • During testing, pulse reached at pin 2 of IC1 is of 1.2Hz frequency with near 47% dutycycle. The voltage swinging is in 1.4V to 2.1 V range (not very accurate measurement)
  • Voltage available at pin 5 of IC1 is from 0.8V (P1 fully counter clockwise) to 4.5V (P1 fully clockwise)
  • When P1 is in fully counterclokwise , LED2 is ON and LED3 is OFF. When P1 travels beyond its mechanical centre position LED3 also turned to ON state. When P1 is in fully clockwise, both LEDs are in ON state but now with a different pattern. Amazing visual effects created by the three LED combination is very difficult to describe in detail. Get ready to watch it yourself!

6 Comments

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  • zack

    hi guys pleas will you kindly assist me on which circuit to use because i want to make a price list,using leds

  • V.Ramakrishnan

    It is really a great idea to me to try.Further I want to use these types of LEDs with AC for which your help is needed.I have been following your articles in EFY for so many years.Thanks for providing a good circuit to make with.

  • Jacques

    I like the idea of a multi color LED lights. I have security garden beams in my yard connected to a activation panel in the house. This is connected to a siren. However when the siren goes off I don’t know which one of the beams went off. I want to connect LED lights to each beam. The LED must then switch one when the beam is broken to remain on for maybe 2 minutes to show me which beam were activated. Can you maybe help me with the Parts required and maybe a diagram to make the little board.

    I must say that I have no electronic experience.

  • Robert

    Love it. I have always liked lighting effects from simple color organs to laser controls since I was a kid. Thanks for your contribution, I am going to teach my grandson to build this on my Heathkit training lab.

  • Jim Keith

    Clever triggering of the 555 timer–I had thought that I knew everything about the 555, but this one proved me wrong.

    I wonder what they put inside the flashing LED (LED1)…

    • T.K.Hareendran

      Really inspired by your feedback, dear Mr. Jim Keith!

      I am fortunate enough to found that there is a “chip” inside this wonder LED. You can experiment with a microscope (even at 45 – 60x magnification) to see the inside magic. Further, we have an unusual electronic component that produces a random sequence of currents when voltage is applied. We can use this current/pulse to control other circuitry as done here. I got an accurate clock pulse 1.2 Hz /47%; sweet ‘n’ simple gift from an odd brain !

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