Using a couple of CMOS ICs and a handful of passive electronic components, a circuit producing a beautiful LED running light effect can be constructed. Here we'll show you how it's done.
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A Simple CMOS IC 4017 Circuit for an LED Running or Chasing Effect
The heart of the circuit of this LED running light is the CMOS IC 4017. You have already learnt quite a bit regarding the pin designation of this IC in one of my previous articles. There we have discussed that when a clock signal is applied to pin 14 of IC 4017, its outputs change state sequentially with every rising edge of the clock pulse. This property of the IC can be utilized to construct numerous different electronic projects. You may also like to refer to my article on the construction of a combination lock where the same feature of the IC has been exploited.
By connecting a group of LED s to the outputs of the IC 4017 and applying a clock pulse at pin 14, the LED s can be illuminated sequentially, giving a running or chasing effect. This is exactly how the present circuit of the LED running light functions.
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An IC 4049 Provides Clocking for the Circuit
Without an oscillator clock pulses cannot be generated, hence it is also an important and integral part of this circuit. There are unlimited options to get an oscillator configuration using IC s like 741, 4093, 555, transistor mutivibrators etc. For the present circuit I have used IC 4049 to get a square wave signal. Out of the six gates in this CMOS IC, only two have been used to get the required frequency output that drives the IC 4017. Another good oscillator configuration may be tried using IC 4060.
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Parts List for the LED Running Lights
You will need the following parts to construct the circuit of this LED running light:
IC 4017 - 1no.
IC 4049 - 1no.
Resistor 100k Ω 1/4 watt - 1 no.
Resistor 150 Ω 1/4 watt- 10 no.
Capacitor 4.7uf/25V - 1 no.
General purpose board - 5" / 3" - 1 no.
LED (color as per your choice) - 10 nos.
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Construction of the Light Chaser Circuit
The construction procedure is done through the following simple steps:
Begin the assembly of the LED running light circuit by fitting the two IC s somewhere in the middle of the board, leaving some space in between them.
Complete the oscillator section first, by connecting the 100 k and the 4.7uf capacitor to the appropriate pins of the IC 4049 as per the given diagram,
DO NOT forget to connect the unused inputs of the gates either to a logic 1 or a logic 0. The unused outputs can be left open.
Next wire the IC 4017 and interconnect the two IC with the help of the diagram,
Connect the LEDs with the current limiting resistors of 150 ohms to the outputs of the IC 4017 in serial order of its output pins as - 3,2,4,7,10,1,5,6,9,11.
The LED s may be connected such that their tips protrude out of the edge of the board.
A built in power supply may be constructed using a transformer and a bridge diode configuration, or a battery may be used to power the circuit.
Now if everything is placed rightly, switching on the power will instantly start the LEDs flashing in a sequence, giving it a real running effect,
The entire circuit of this LED running light may be fitted in a nice looking ABS enclosure with the LEDs projecting out of the box.
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Manually Operated LED Light Sequencer Circuit
The above circuit of a manually operated LED sequencer has been presented on a request from Mr.Bruce Nelson. The circuit was designed in view with the following request:
I saw your post on the Electronics Circuits forum. I am hoping you can help me with a circuit design.
I'm not sure what you would call it, and there may even be an IC that does what I need, but let me describe the circuit. I have momentary, normally open pushbutton and 6 LEDs, and everytime I press the button I would like the circuit to activate LED 1. Press it again and LED 1 is turned off and LED 2 is turned on. Press it again and LED 2 turns off and LED 3 turns on, and so on. When LED 6 is activated and the button is pressed, I need the circuit to turn off LED 6 and turn on LED 1, wherein the cycle starts over again, cycling through the LEDs with each press of the button, 1 thru 6, then back to 1.
Like I said, there is probably an IC out there that will do this, but I am unfamiliar with what to look for.
Can you help me?
Thank you for your time,
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Manually Operated Sequential Relay Circuit
The circuit described in the previous section can also be used to operate relays, the circuit shows how to configure the relay stage to the earlier circuit.