555 Knight Rider Circuit : 10 Steps

A LED knight rider circuit is fairly popular on the internet and the circuit is also easy to find. This tutorial will show you how to construct the circuit step by step.

This is the final project for PHYS339. PHYS339 focusses on ICs so this project is all about how NE555 AND 4017 circuits work together.

To make the circuit easy to follow, we'll separate the connections to 555 timer and the 4017 decade counter.

Schematic courtesy of http://www.555-timer-circuits.com/

You will need the following components:

Breadboard

NE555 Bipolar Timer

8 x 100 Ohm Resistors

2 x 220 Ohm Resistors

6 x LEDs

4017 Decade Counter

1k Ohm Resistor

68k Ohm Resistor

Pickup wires

9V battery and battery clip

3.3 uF Capacitor

Step 1: Background

In this project, the 555 is astable mode. The output is constantly switching between high and low value. We can also change the frequency (which would make the LEDs flash faster or slower,) by changing the value of the resistors (putting a potentiometer would be fun). The output (pin 3) is then connected to the 4017 counter. The 10 outputs of the 4017 counter switch from one to another when 1 cycle of the 555 timer is completed.

Step 2: The 555 Timer

The redrawn schematic is a representation of what the circuit should look like on the breadboard. Pay close attention to what wire coming from what pin to what pin. The longer end of the capacitor (+ sign on the schemic should go to pin 1). Due to the size of the capacitor and the space between rows on the breadboard, the longer end of the capacitor is moved 2 rows up. Pin 3 is for connecting to the 4017 decade counter.

Step 3: 4017 Decade Counter, LED & Resistors

Start by laying down the LEDs and then the resistors. Remember the short end of the LED goes to ground. Make sure to leave some space among the LEDs for the resistors.

Starting from the top, the first LED to D1 down to D6. D1 and D6 are each connected to a 220 Ohm resistor. D1 goes to Q4, which is pin 10 on the decade counter. D6 is pin 3.