Check Your Components


555 Timer Ic - 2


4020 IC - 1


Red LED's For Cube - 33


33K Ohms Resistor - 2


10uf Capacitor - 2


4017 IC - 1


10nf Capacitor - 2


IN4148 Diode - 8


10K Ohms Resistor - 3


15K Ohms Resistor - 3


22K Ohms Resistor - 2


Buzzer - 1


1K Ohms Resistor - 1


68K Ohms Resistor - 1


3.3uf Capacitor - 1


220e Ohms Resistor -1


100e Ohms Resistor - 1


4.7k Ohms Resistor -2

1Watt pot-500x500

100k Pot - 1


100nf Capacitor - 1


2.2uf Capacitor - 1


470r Ohms Resistor - 6


Bc547 Transistor - 2


100k Ohms Resistor - 1


100uf Capacitor - 2


47K Ohms Resistor - 1


Green LED - 1


Yellow LED - 1


12v Relay - 1


IN4007 Diode - 1



220k Ohms Resistor - 1


39r Ohms Resistor - 1


BC557 Transistor - 1


9v Battery Set - 1


Single Stand Wires

Breadboard 170 Tie Points 1-500x500



Wire Stripper

Experiment - 1 Knight Rider

Description :

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 10 outputs Q0 to Q9 become active, one at a time, on the rising edge of the waveform from the 555. Each output can deliver about 20mA but a LED should not be connected to the output without a current-limiting resistor (100R or 220R). 
Using six 3mm LEDs, the display can be placed in the front of a model car to give a very realistic effect. The same outputs can be taken to driver transistors to produce a larger version of the display. 

Experiment 2 - Traffic Lights

Description :

The animation shows the lighting sequence and this follows the Australian-standard. The red LED has an equal on-off period and when it is off, the first 555 delivers power to the second 555. This illuminates the Green LED and then the second 555 changes state to turn off the Green LED and turn on the Orange LED for a short period of time before the first 555 changes state to turn off the second 555 and turn on the red LED. A supply voltage of 9v to 12v is needed because the second 555 receives a supply of about 2v less than rail. This circuit also shows how to connect LEDs high and low to a 555 and also turn off the 555 by controlling the supply to pin 8.  Connecting the LEDs high and low to pin 3 will not work and since pin 7 is in phase with pin 3, it can be used to advantage in this design. 

Experiment-3 WakeUp Alarm

Description :

This  circuit will increase its sound based on the light intensity of the room. Can be used as a morning alarm, which can produce an highly irritating sound when sun goes up.

Experiment 4 -Police Lights

Description :

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. When the timer's output changes to a high state this triggers the a cycle on the 4017 4017 decade counter telling it to output the next sequential output high. The outputs of the 4017 are connected to the LEDs turning them on and off. 

Experiment 5 - Light Detector

Description :

This circuit detects light falling on the Photo-cell (Light Dependent Resistor) to turn on the 555 and create a tone that is delivered to the speaker. Pin 4 must be held below 0.7v to turn the 555 off. Any voltage above 0.7v will activate the circuit. The adjustable sensitivity control is needed to set the level at which the circuit is activated. 

When the sensitivity pot is turned so that it has the lowest resistance (as shown in red), a large amount of light must be detected by the LDR for its resistance to be low. This produces a voltage-divider made up of the LDR and 4k7 resistor. As the resistance of the LDR decreases, the voltage across the 4k7 increases and the circuit is activated. 
When the sensitivity control is taken to the 0v rail, its resistance increases and this effectively adds resistance to the 4k7. The lower-part of the voltage-divider now has a larger resistance and this is in series with the LDR. Less light is needed on the LDR for it to raise the voltage on pin 4 to turn the 555 on. 

Experiment 6 - Machine Gun

Description :

This circuit produces a sound very similar to a machine gun:

Experiment 7 - 3x3x3 LED Circuit

Description :

This circuit drives a 3x3x3 cube consisting of 27 white LEDs. The 4020 IC is a 14 stage binary counter and we have used 9 outputs. Each output drives 3 white LEDs in series and we have omitted a dropper resistor as the chip can only deliver a maximum of 15mA per output. The 4020 produces 512 different patterns before the sequence repeats and you have to build the project to see the effects it produces on the 3D cube. 

Experiment 8 - Music Box Circuit

Description :

This circuit produces 10 different tones and by selecting suitable values to change the voltage on pin 5, the result can be quite pleasing. Note: the two unused outputs of the 4017 produce a tone equal to that produced by the 555 when pin 5 has no external control voltage.

Experiment 9 - Wake Up Alarm

Description :

The 555 will activate a relay. When pins 2 and 6 are connected as an input, the chip requires only about 1uA to activate the output. This is equivalent to a gain of about 200,000,000 (200 million) and represents about 4 stages of amplification via transistors.
In the first circuit, the output will be opposite to the input. The relay can be connected "high" or "low" as show in the second diagram. One point to note: The input must be higher than 2/3V for the output to be low and below 1/3V for the output to be high. This is called Hysteresis and prevents any noise on the input creating "relay chatter."