Knight Rider LED Chaser Circuit

The article discusses the construction details of the popular "knight rider" chaser circuit incorporating LEDs as well as mains operated bulbs through triacs. The proposed circuit is transformerless and is thus a lot compact and light weight.

The Circuit Concept

It's basically a light chaser or a running light effect generator circuit, quite resembling the effect produced over the popular "knight rider" car.


The circuit mainly comprises of IC 555 and the IC 4017 for implementing the required functions. The IC 555 is used to generate the clock pulses which is fed to the clock input of the IC 4017.

These clock pulses received from the IC555 is translated into a sequencing or chasing effect over the LEDs connected across the various outputs of the IC 4017.

In its normal mode the IC 4017 would have generated a simple start to end sequencing of the LEDs wherein the LEDs would have lit up and shut off one after the other in a sequencing pattern with a rate determined by the IC555 cock frequency, this would repeat continuously as long as the unit stays powered.

However in the proposed knight rider LED light chaser circuit, the output of the IC4017 is configured in a special way using a group of diodes which enable the output sequencing to produce a to and fro chasing of the connected LEDs, albiet through 6 LEDs only in contrast to 10 LEDs as in the normal mode.

How the Circuit Works

As can be seen in the first circuit diagram, the design produces a reverse forward moving effect of the LEDs in response to the clocks generated by the IC555 which is basically wired as an astable.

The frequency of this astable can be varied by adjusting the associated 500k pot which in turn influences the LED sequencing speed.

The entire circuit is powered via a compact transformerless power supply circuit thus avoiding the need of bulky transformers or costly SMPS.

This circuit can be also modified for illuminating mains operated bulbs by incorporating a few triacs in conjunction with the LEDs present at the outputs.

The second figure shows the complete arrangement where we can see 6 triacs being rigged across the output LED ends via 1 K resistors.

Again, this mains operated knight rider light chaser does not depend on bulky power supply stages rather employs a simple capacitive power supply for implementing the proposed running light or chasing LeD effect.



Knight Rider Circuit using 220V Mains Lamps



Knight Rider Chaser using 12V Bulbs

The above circuit can be also as effectively used for car installation by doing the following modifications to the above circuit. The circuit shows how the design can be used for illuminating 12V car automotive lamps.





91 thoughts on “Knight Rider LED Chaser Circuit

  1. Have questions? Please feel free to post them through comments! Comments will be moderated and solved ASAP.
    when i make a triac circuit should i use led for out put stage of 4017? or can i triger bt136 with out led bulb (can we use capacitor like 104 insted of led)


    • Thanks!

      LEDs can be eliminated for the triac circuit, they are not required, but the resistors should be included. Capacitors wil not work in place of the LEDs.

      The LEDs provide an indication how the triacs are switching.

    • sir,

      i tried to find 12V 2W zener diodes but couldn't in my can i used 12V 1W zener insted of 12V 2w zener or any other circuit modification for used 12V 1W zener


    • SIR,
      the 230v circuit was build.but it not work so i check voltage of 4017 was 2.5V. zeners are good (12v 1w 2 in parallel.)
      please let me know how to solve this problum


    • SIR,
      i used computer power supply (12V)as power source.then it was worked properly (triac was disconnected & used LED for out put stage of 4017 IC)and supply voltage of ic was indicated please guide me.


  3. I've made the 12V car version. I've only left out the leds before the mosfets. But it's not working. When I don't connect the positive wire going to the 22k resistor, port 8 and 4 of ic555 and to port 16 of ic4017. All the light are burning, but when i connect this positive wire nothing is working at all. Have you any idea what could be wrong and how i can check it?

    • that's weird, because without the positive supply connected the LEDs would never light up.
      I think there's something terribly wrong with your connections or the components.

      Separate the 555 and the 4017 stages….build and test them separately, once the results are confirmed you can try integrating them as per the diagram.

  4. sorry sir,
    apne samay nikal kar mere prashna ka jabab diya,lekin kam ke bajese me try nehi kar saka.
    aj mene try kiya led negetive se 1k lagaker GND se connect kiye.lekin 12v 2amp smps se sequence tut raha he. plz sir help me.

  5. sir,
    triac ke gate aur GND par 1k connact kene par sequence sahi arahahe thanks. lekin triac 100w bulb flash nehi ker rahaye. No.1 chanel se sirf flash ho raha he, lekin lumin kam ho raha he.
    me ne 1k ke jaga 220E resistance se triac ke gate connect kiye,lekin No.1 chanel chor ke baki sab off he.lumin thora sa change huya lekin baki kam nehi ker raha he.
    sir triac
    pin-3-G.circuit me to is hisab se nehi he….sir plz help me…..

  6. sir
    mene 12v 2amp adapter use kiya.led sequence sehi aarahahe.lekin triac kam nehi chanel kam ker rahahe100w bulb lagane par lumin kam ho rahahe.baki ke 5 chanel off he.

    • connect a LED with 1k resistor from pin3 of IC555 to ground, it should flash, if it doesn't then the fault could be assumed to be in the 555 circuit, other wise the fault could be in your 4017 circuit….make sure all the LEDs at the gate of the triacs are connected correctly and illuminate for enabling the triacs to conduct.

  7. thanks sir
    circuit sahi se kam ker rahahe.1k ke badle mene 220E resrstor triac gate se connect ki ya aur apke bataye huye,1k resistor gate aur circuit GND se connect kerne par led sequence sahi a rahahe.aur triac proper kam ker rahahe.sab chanel 100w lamp se try kiya lumin sahi a raha he.
    sir mene triac pin 1-A1 aur pin 2-A2 hisab se lagaya. thanks sir guide karne ke liye.
    you r great……..

    • thanks, that would be possible with a normal IC 4017/555 chaser circuit without the forward reverse facility….there you can achieve it by simply reversing the LED polarity….I am not sure how it could be done in the above circuits….may be by reversing all the diodes an LED polarity, but I am not very sure.

    • Hello Sandeep,

      see the last circuit, you can replace the bulbs with the LEDs with a series resistor.

      The mosfets can be replaced with a TIP 122 transistor as an alternative.

      You can connect 3nos of 1 watt LEDs with a resistor on each transistor

  8. i am telling you after check and i can prove it
    and i am telling you that please check in circuit

    capacitor, diode and Zener diode put in the wrong direction in your second picture circuit

  9. triac is fitted in the way your circuit but do not get that way for the entire supply triac and because of which fully AC supply cannot send. so will need to use transistors

    now you make your circuit and used
    and then some comment

  10. सर जी क्या मैं C 0.47uf/400V की जगह पर कोई और C use कर सकता हूँ सर जी अगर कोई और C हो तो बता दो पर circuit के लिए सुरक्षी हो 🙂

  11. sir मैं इस प्रोजेक्ट से हट कर एक सवाल पूछ रहा हूँ क्या मैं BTA41,BT139 और BT136 को Thyristor (SCR) की तरह use कर सकता हूँ

    • Dear sir मेरे other circuit का कहने का मतलब है के दुसरे circuit द्वारा प्राप्त output voltage 0 से 0.8 DCV 200uA dimmer के लिए कम जादा कर सकते है जो की Triac को Triac Dimmer बनाने के लिए पर्याप्त नहीं है
      तो मैं आपसे ये जानना चाहता हूँ triac को dimmer बनाने के लिए अभी कौन कौन से components की जरुरत पड़ेगी ?

    • Dear Rakesh.

      0.8V will need to be amplified first with a 12V amplifier circuit or an optocoupler circuit….the output from this optocoupler can be used for driving the triac.

      MOC3063 can be used for this.

  12. Dear sir 240V AC में, मैं अगर सिर्फ एक 1N4007 diode का use न्यूटल या फेस कर तो मुझे output voltage कितना मिलेगा ?
    Please tell me sir

    • Dear sir आपने जो output बताया है मुझे इसी voltage से BTA41 को ऑपरेट करना है कैसे करूँ कोई ऐसा हल बताइए जो circuit के लिए सेफ हो
      Please sir

    • connect a 1k resistor to triac gate and then connect a 0.33uF/400V capacitor and connect this capacitor end with the 120V input….also connect a diode 1N4007 parallel with the capacitor….cathode will be towards the 120V source.

    • It's very simple…connect 120V input with the band side of a 1N4007 diode, connect the other side of the diode with 1K resistor, connect the other end of the 1K with the SCR gate.

      after this connect a 0.33uF/400V capacitor right on the leads of the 1N4007

  13. मतलब आपके कहने का अर्थ है 1N4007 के output से 0.33uf/400v को जोड़ना है और फिर 0.33uf/400v के एक छोर से 1k जोड़ना है और फिर 1k से Triac gate को जोड़ना है ok sir

  14. Dear sir मैं आपसे कुछ इस तरह से Triac (BTA41) को Drive कर ने के लिए कह रहा था
    मैंने आपके mail id पर दोबारा से image send किया है
    क्रप्या इस image को देखे
    Please Sir मुझे इसका हल बताइए

  15. Dear sir आपके दिये हुवे second circuit image में main power supply का जो circuit है उसके जरिये MOC3021 drive करने के लिय कितने value के resistance की जरुरत पड़ेगी
    और इस supply के जरिये हम एक साथ maximum कितने MOC3021 का use कर सकते है

  16. Dear Swagatam,

    I have built the first circuit but without the high voltage part and the Zener diode.
    It works fine at max. 5V

    If I raise the voltage to above 5V the flashing of the LEDs becomes uncontrollable.

    What do I need to change to use the circuit at 12V?

    Thank you in advance,

    • Hi Henrik, that shouldn't happen, because IC 555 and IC 4017 both are designed to work from 5V to 15V safely. THis can happen if the power supply has some issues, or if the power supply pot is not good.

      try with a fixed 12V and see if the problem still persists.

      or alternatively you can also try readjusting the IC 555 pot after increasing the voltage to the desired higher level

  17. Dear Swagatam,

    Thank you for your reply.
    I have tried all your solutions but unfortunately with the same result.
    I think it is weird because as you said the ICs are rated up to 15V.


    Is it possible to build a small circuit without the use of a microprocessor for flickering some LEDs?
    The flickering must simulate an arc welder, camp fire, candle light etc.?

    Best regards,

  18. Sir I new and I am intreste to make circuit as per diagram 2. But sir the capacitor 1uf as shown in diagram connected near ic 555 the voltage of capacitor is not given. Please provide what is the volt of 1uf capacitor.

  19. sir this transformerless cct is it possible to construct it and without connecting load is it possible to measure voltage on that zener diode without spoiling the zener?

Leave a Comment