# Knight Rider LED Flasher - 555 & 4017

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## Introduction: Knight Rider LED Flasher - 555 & 4017

In this instructable I will show you how I made an LED flasher with Knight Rider effect(Larson Scanner) with the famous integrated circuits 555 timer and 4017 johnson counter.

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## Step 1: Demonstration

Here you can see the finished project.

## Step 2: Parts List

For this instructable you will need:

1x - Knight Rider PCB (or some perfboard)

1x - SPDT slide switch

1x - 9V battery clip (6f22)

9x - 1N4148 or any other general purpose diode

6x - LED (whatever color/parameters)

1x - 100nF capacitor

1x - Potentiometer 500kΩ linear

1x - 10 kΩ resistor

1x - 2.2 kΩ resistor

1x - 555 timer

1x - 4017 johnson counter

Optional:

1x - 8 pin socket

1x - 16 pin socket

## Step 3: Schematic and Board

HOW IT WORKS

This circuit can work on voltages from 4.5V to 16V

The integrated circuit NE555 is wired in an astable mode(oscillator) and is used as a clock signal for 4017. The 100nF capacitor(C1) with the potentiometer(R2) wired as an adjustable resistor set the frequency of the oscillation.

The 4017 is a 5-stage johnson counter. This may not tell you much so I will try to explain. With each oscillation of the 555 timer the counter proceeds to the next output and so on. Just look at the gif and you should Immediately understand.

The LEDs can be used with just one resistor(R1) as only of them is lit at a time.

For the schematic and PCB I used a free program CadSoft Eagle which I would recommend to anyone making schematics or PCBs.

## Step 4: Etching the PCB

I did not make the video.
I etched the PCB with i guess "photographic method" - that would be the direct translation from my language. I printed out the PDF file from previous step on transparent foil and then shone through it on photosensitve PCB, then developed it in solution of sodium hydroxide and then etched it in ferric chloride. If you find it confusing just watch the video, It's very well explained. Also don't forget to orient the transparent foil on the PCB so that you can read the words written on it.

## Step 5: Perfboard Version

If you don't have the equipment to develop your own PCBs or you think it is expensive then it is possible to make this on perfboard as I did my first version. Unfortunatelly I don't have the board design in eagle so you will have to come up with your own.

There is one difference in the perfboard version that I have put a led on the output of NE555 to see the clock signal. I decided that I don't need this feature in my final version.

Good luck.

## Step 6: Soldering

At first I soldered all the flat components and then the higher ones. If you followed the instructions carefully the circuit should work on the first try.

## Step 7: Conclusion

For me this was a fun project and a good practice in PCB design and soldering.

If you manage to build this project don't forget to post your results into the comments.

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## 10 Discussions

Why do I need to place capacitor? What's the role of that?

I can connect this with strip led or not

A great little circuit for anybody starting out in electronics as a hobby. The only downside of this circuit is the sharp "on-off" effect that results as the LED's are cycled by the 4017. During the 80's there was an article in ETI magazine that described a more realistic circuit called "ETI Knight Lite" that gave the effect of "smearing" the output over three LED's at a time to provide a more realistic look, as seen in the real life application in the TV series.

I have been searching the ETI archives unsuccessfully so far for a copy of the article, perhaps somebody on the forum can assist?

Maybe you can put capacitor. For memorize the light. For tails effect

Nicely done. Quality Instructable.

One FYI. Officially this is called a "Larson Scanner" after its creator Glen A. Larson, creator of many great 80's sci-fi shows that incorporated these devices into props.
The two most well known being KITT from Knight Rider and the Cylon Centurions from Battlestar Galactica.

Wow. Do I feel old giving a history lesson on TV shows I grew up with!
;')

I love knight rider but I how to make this with arduino uno

why would you need an arduino if you can do it with 2 chips at a cost of few cents ?

While I haven't built this particular circuit, I have made tons of PC boards over the years and I like the PNP blue paper method myself. I have tried the photographic method, but not the one you posted here. I also used commercial PCB manufacturers with great results too. But building them at home is both fun and cost effective. Thumbs Up.