Have you ever been robbed while asleep and felt if you were are awake or someone woke you up, you could have prevented the robbery, something similar happened to me and it inspired me to make this DIY alarm. Its is not 100% percent good but it better than nothing. So let get started.....

Step 1: Components and Stuff Needed

1. CD4017 ic

2. L293D ic

3. 9.1k resistor (any resistor from 2k ohms to 10k ohms should work fine)

4.8 pin IC socket (i mean 8 pins on both sides which sums up to 16 pins)

5. Stripped vero board or any of your choice

6. 7805 ic

7.Active buzzer (3v - 24v)

8. wires

9. Proximity sensor

10. 12V DC jack

Step 2: Tools Needed

1. Soldering iron( i use a 60 watts soldering iron)

2. Solder

3. Third hand with magnifying glass (optional)

4. Multimeter

The links attached to the components and tools are links to a Nigerian electronic component store but you can also check the component and tools on ebay, amazon, digi key, sparkfun, bangood , aliexpress and so on

Step 3: IC CD4017

the ic cd4017 is a decade counter. it sets it output on and off consecutively(one after the other) anytime a pulse is sent to it.

WHAT IS A PULSE?????

Pulse (signal processing) - Wikipediaen.wikipedia.org › wiki › Pulse_(signal_processing)A pulse in signal processing is a rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return ..

CD4017 Pin Configuration

1 to 7, 9 and 10 and 11 (Q0 - Q9)are the outputs pins of the cd4017
pin 8 is vss or gnd
pin 12 (not needed in this project)
pin 13 this should be connected to GND , if HIGH it would hold the count at the current state( if pin 3 was high and pin 13 was made HIGH pin 3 will stay HIGH and will not change its state even if you send a pulse, you have to set pin 13 LOW(connect to GND before the chip will go back into normal operation)
pin 15 is the reset pin( starts the whole process from the beginning pin3(Q0)
pin 16 is vdd( voltage power supply (5v for this project) voltage range= 3v to 15v)

N:B when the chip is powered pin 3 (Q0) comes on first.

Step 4: L293D

This is a dual H bridge driver. i used it to drive(to turn on and off ) my buzzer with 12v. it has 16 pins

pin 1(EN 1) activates the first H bridge( it has to be set HIGH(i think 2.5v - 5v) should set it HIGH)
pin 2 is INPUT 1 (IN 1) which controls the state of pin 3 (which is OUTPUT 3)
pin 3 is OUTPUT 1
pin 4,5,12,13 are GND should be connected to GND
pin 6 is OUTPUT 2
Pin 7 is INPUT 2 which controls OUTPUT 2
Pin 8 is connected to voltage supply( which is 12v or higher but must not exceed 24v) this voltage is for driving our buzzer.
Pin 16 should be connected to 5v
We wont be using the other pins for this project

Step 5: 7805 Ic

This is the simplest ic we would be using in this project. it has 3 pins. This ic steps any voltage from 7V - 32V down to 5V . if it begins to heat up, i advise to use a heat sink, but i have not really notice mine heating.

Pin 1 is the voltage supply pin, 12v should be connected to it.
Pin 2 is GND pin and should be connected to GND
Pin 3 is the Voltage output pin, this is where our five volts comes out from

Step 6: THE INFRARED (IR)PROXIMITY SENSOR

This sensor is has two diodes one emits(ir transmitter) infrared light the other senses infrared light.

PRINCIPLE OF OPERATION:

When the sensor is turned ON the IR transmitter emits infrared light, when this light hits and obstacle it bounce back and the IR receiver receives it.

The IR sensor module i used sends a LOW signal when IR light bounces back to it. To check if yours is HIGH or LOW connect the +ve (anode) of and LED with a 330 ohm resistor to the output of your IR sensor and then connect GND of your IR sensor to the LED cathode, connect 5v to your IR sensor and connect its GND to GND of your power supply .. Take your hand close to it the IR sensor(where the actual sensors are(the diodes(the look like LED)) if the LED come on that means your sensor is SENDS a HIGH signal when it receives IR light but if the LED was ON even before you got close to it and when you take your hand close to it goes OFF then it is works like mine.

for more information on IR sensors and its modules you can always search the internet or check the videos from youtube

Step 7: Creating the Circuit : Soldering the Ic Sockets

plug your ic sockets into the vero board with the their pins in the copper side, solder them to your board, then scrape of the copper between their pins, this disconnects pins on adjacent side, do not forget to do this, or else it wont work or worse you might damage your circuit . do this for both ic socket. you can use your multimeter to check if any adjacent(opposite) side of the ic sockets are connected. set you multimeter as in the image if the two leads were to touch each other it would make a sound so you can use this to check if you properly scraped off the copper in between opposite pins. Refer to the image to the third and fourth image for proper understanding.

Step 8: Schematics and Connections

CD4017

connect

pin 3 to pin 7 of l293d

pin 8 and 13 to GND

pin 14 to the output of our proximity sensor

pin 15 to one end of the 9.1k ohms resistor to the other end of the resistor should go to GND

one end of the tact switch should go 5V (pin 3 of 7805 I.C) and the other end should go to pin 15 (directly to pin 15)

pin 16 to 5V (pin 3 of 7805 I.C)

WE WON'T BE USING THE OTHER PINS

L293D

pin 1,2, 16 to 5V (pin 3 of 7805 I.C)

pin 3 to +ve lead(wire) of buzzer pin 6 to -ve lead(wire) of buzzer

pin 4,5,12, 13 to GND

pin 7 to pin 3 of CD4017

pin 8 to 12v(pin 1 of 7805 I.C)

we wont be be using the other pins

7805 I.C

pin 1 to 12v

pin 2 to GND

pin 3 gives out 5V

IR sensor module

Vin to 5V

GND to GND

OUT to PIN 14 of CD4017

12V DC JACK

connect the +ve of your dc jack to pin1 of 7805 IC

connect the negative to GND

Step 9: Debugging

if the buzzer doesn't maybe you connected it wrongly , so just reverse the connection, if th whole circuit doesnt work at all, use your multi meter to check for short circuits or poor connections.

if you have any problems, just ask me in the comment section. Thank You.

Introduction: DIY ALARM