The following article explaining a 200 nos. LED forward reverse light chaser circuit was requested by Mr. Nagaraj. Let's learn more regarding how to implement the proposed high number LED light chaser circuit.
Actually the present design is a modification of a previously discussed light chaser circuit which utilized just single LEDs per channel, that's five in all for the whole circuit.
Just five LEDs surely won't look very impressive and that's exactly why the request was made.
The circuit diagram shows a simple yet an effective configuration which is able handle up to 200 different colored LEDs and create the required to and fro chasing show.
The IC 4017 is the main part of the entire system whose outputs have been very cleverly manipulated using diodes.
Normally, in response to a clock signal the outputs of a 4017 IC would begin shifting sequentially from pin#3 to pin#11 covering ten of its pin outs in a certain random order.
If the LEDs are arranged in these ten outputs, one would acquire ordinary one direction sequencing of the LEDs.
In the discussed circuit, five of the end sequence pin outs have been diverted in such way that the connected LEDs produce a to and fro moving effect, however with this arrangement the total number of outputs get restricted to only 5, nevertheless sufficient for implementing the intriguing visuals.
Normally the outputs would accommodate a maximum of 4 LEDs, a total of 20 numbers. For handling as high 200 LEDs, transistor buffer stages have been included in the circuity.
Each transistor or the channel can hold upto 50 LEDs, the LEDs are connected in series and parallel combination as shown in the last diagram.
The LEDs are connected to the collector of the respective transistors as referred to in the last diagram.
The IC 555 is wired up as an astable for generating the required clock pulses at the input pin#14 of IC 4017.
These clocks determines the sequencing rate of the connected LEDs which may varied by adjusting variable resistor R3.
The circuit may be powered from a 12V battery or a 12V/3amp SMPS adapter unit.
The basic reverse forward LED circuit using single LEDs can be studied elaborately in this LED scanner article, and the video can be witnessed below:
How to Connect the LEDs
The following diagram illustrates the connection arrangement of the LEDs to the above circuit. A single series for each channel has been shown in the diagram.
The numbers can be simply increased just by inserting more such series in parallel to the respective strings of the different channels.
R1 = 1K,
R2 = 4K7,
R3 = 1K,
R4 = 100K pot, linear,
C1 = 10nF,
C2 = 4.7 uF/25V,
IC1 = 4017,
IC2 = 555
All diodes are = 1N4007
All transistors are = BD139
All transistor base resistors are = 1K
LED resistors are = 150 Ohms 1/4 watt.