The 555 timer is a simple integrated circuit that can be used to make many different electronic circuits. With this information you will learn how how the 555 works and will have the experience to build some of the circuits below.

The 555 Integrated Circuit (IC) is an easy to use timer that has many applications. It is widely used in electronic circuits and this popularity means it is also very cheap to purchase, typically costing around 30p.

KNIGHT RIDER Circuit This circuit mimics the lights in knight rider's car. They flash one at a time chasing each other. Overview In the Knight Rider circuit, the 555 is wired as an oscillator (Astable mode). The output of the 555 is directly connected to the input of a 4017 decade counter. The input of the 4017 counter is called the CLOCK line.

The 555 can be used as an amplifier. It operates very similar to pulse-width modulation. The component values cause the 555 to oscillate at approx 66kHz and the speaker does not respond to this high frequency.

The output of the 555 drives a transistor to turn a globe on and off. The second circuit is a Memory cell and is the basis of the memory in a computer. The SET button turns on the globe and the RESET button turns the globe off.

SERVO TESTER Circuit This circuit can be used to manually turn a servo clockwise and anti-clockwise. By pushing the forward or reverse button for a short period of time you can control the rotation of the servo. It will also test a servo.

ROULETTE Circuit This circuit creates a rotating LED that starts very fast when a finger touches the TOUCH WIRES. When the finger is removed, the rotation slows down and finally stops. View All Circuits

POLICE LIGHTS Circuit This circuit flashes the left LEDs 3 times then the right LEDs 3 times, then repeats. Overview This circuit uses a 555 timer which is setup to both runn in an Astable operating mode. This generates a continuous output via Pin 3 in the form of a square wave.

The output structure of the timer is a “totem-pole” design, with Q 22 and Q 24 being large geometry transistors capable of providing 200mA with a 15V supply.

STEPPER MOTOR CONTROLLER TE555-1 Circuit The direction of rotation is determined by the FORWARD and REVERSE switches and the motor does not take any current when a switch is not pressed. View All Circuits