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LED Flasher (very Interesting.............)


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Hi guys,
The Chaser circuit will not make the LEDs go back and forth like YOURWINS cool animation of a Knightrider. Instead the LEDs will start with #1, then #2...... up to #10, but the next LED will be #1, then #2 etc. The reason is that the 4017 can only count up, not down. That is why the circuit is called a CHASER. If you put the LEDs in a circle then they will go around and around in ONE direction only.
A Knightrider circuit will need the oscillator to be followed by an up/down counter, a flip-flop to change the direction, then a decoder.

This is just theory, but it is true.

YOURWINS,
Please post an animation of an LED chaser that is in a circle.

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Hi again,
An analog circuit will make an LED Knightrider circuit:
1) A classic 2-opamp ramp generator (1st stage is a comparator with hysteresis and the 2nd stage is an integrator and the stages connect together with feedback).
2) The ramp generator feeds an LM3914 voltage-to-dot driver driving the LEDs in its dot mode.
The lighted LED will appear to continue to go back and forth.

Just more theory, guys.

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yourwins, the article mentions the knight rider lights, so I would assume that it is what you want. In a little more searching I find there is also a knight rider circuit on our site:
http://www.electronics-lab.com/projects/motor_light/035/index.html

Then also here:
http://www.charlton.vic.edu.au/mark/electronics/555_projects/k-rider.html

...and here:
http://www.talkingelectronics.com/FreeProjects/555/555-P3.html

They all seem to be similar. Let us know if it is true that none will give you the knight rider effect as the authors claim.
My own favorite circuit would be to use a microprocessor chip.

MP

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Thanks, MP:
Those circuits WILL light 6 LEDs in a Knightrider fashion. They use diodes as OR-gates, so that 4017's outputs #1 to #6 light LEDs #1 to #6 in sequence, then output #7 lights LED #5, output #8 lights LED #4, etc. and back down to LED #1, then it starts over again.
A brilliant use of diodes as gates. Don Lancaster (CMOS Cookbook) calls it "mickey-mouse logic", but it works well.

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  • 2 weeks later...

;)as nice as it looks . the light chasser circiut has a good use. i biult a double one, that powerd .more than 90 leds but i used it as a lotto number picker, and by taping into the electro and by shorting it out via a push button switch i was able to stop the leds in there tracks ,thus determining the numbers to pick, the numbers were home made decal dots with the numbers written on them with a fine point marker pen. and surgically placed under each led with a pair of tweezers. as for the night rider scanner type if you like the circiut ill post it . and there used to be a similiar intresting one around called the cylon eye but i dont have the circiut for that anymore.

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