Title: Building a Fun and Smart Home with a DIY Smart Doorbell Introduction: In the exciting world of electronics, there's nothing quite as thrilling as creating your very own smart home gadgets. Today, we'll embark on a journey to build a Smart Doorbell using simple and easily accessible equipment like the Arduino Uno, an IR proximity sensor, and a buzzer. This DIY project is not only a fantastic introduction to electronics but also a step towards transforming your home into a tech-savvy haven. So, gear up, young inventors, as we venture into the world of smart homes! Materials You'll Need: 1. Arduino Uno: The brain of our smart doorbell, capable of processing information and controlling the connected devices. 2. IR Proximity Sensor: A nifty gadget that detects the presence of objects in its vicinity. 3. Buzzer: This component will be the voice of our smart doorbell, alerting you when someone approaches. Step 1: Setting Up the Arduino Uno: Begin by connecting your Arduin...
THE 555 TIMER IC
The 555Timer IC is the most popular IC , it is an IC most electronics hobbyist/ enthusiast encounter . it is commonly used to produce variety of waveform using few external RC network.
The 555Timer gets it name from the facts that there are three internally connected 5kohms resistors , which is used to generate the two comparator reference voltages( although , the CMOS version uses three 100kohms resistors) . it is a cheap IC and it's used in precision timing device which can act as either a simple timer to generate single pulses or long time delays or as a relaxation oscillator producing a stablized waveform of varying duty cycles (ranging from 50% to 100%).
The 555Timer is made up of 8 pins and it appears in a DIP package (Dual- in- line package).
The IC can be operated either as a Monostable , Bistable or Astable multivibrator to produce a variety of timing operations such as pulse generation, one shot or delay timers , LED flashers , tone generation, logic clocks etc.
The 555Timer gets it name from the facts that there are three internally connected 5kohms resistors , which is used to generate the two comparator reference voltages( although , the CMOS version uses three 100kohms resistors) . it is a cheap IC and it's used in precision timing device which can act as either a simple timer to generate single pulses or long time delays or as a relaxation oscillator producing a stablized waveform of varying duty cycles (ranging from 50% to 100%).
The 555Timer is made up of 8 pins and it appears in a DIP package (Dual- in- line package).
The IC can be operated either as a Monostable , Bistable or Astable multivibrator to produce a variety of timing operations such as pulse generation, one shot or delay timers , LED flashers , tone generation, logic clocks etc.
555 TIMER CIRCUITRY,BLOCK DIAGRAM AND EXPLANATION
The single 555 timer is a 8-pin Dual in-line Package (DIP) device consisting of 25transistors , 2 diodes, and about 16 resistors arranged to form two comparators , a flip-flop and a high current output stage.
PIN 1( GROUND): it connects the 55timer to the negative supply.
PIN 2(TRIGGER) :it is the negative input of the comparator (u1) .A negative pulse on this pin "sets" the internal flip flop when the voltage drops below 1/3vcc causing the output to switch from LOW to HIGH state.
PIN 3(OUTPUT):This is the output of the IC ,the output voltage is approximately Vcc-1.5v and it is capable of sourcing or sinking 200mA
PIN 4(RESET): This pin is used to reset the internal flip flop.it is an active-low input and it is generally connected to a logic"1" when not used to avoid unwanted resetting of the output.
PIN 5(CONTROL VOLTAGE): This pin controls the timing of the 555timer by overriding the 2/3vcc level of the voltage divider network. when voltage is applied to this pin the width of the output can be varied independently of the RC timing network.it is usually connected to ground via a 10nf capacitor( to eliminate noise) when not in use.
PIN 6(THRESHOLD): This is the positive input of the comparator (u2).it is used to "reset" the flip-flop when ever the voltage at it's input exceeds 2/3vcc ,causing the output to switch from HIGH to LOW . it is connected directly to the RC timing circuit.
PIN 7(DISCHARGE): This pin is connected directly to the collector of an internal NPN transistor which is used to discharge the timing capacitor to ground whenever the NOTQ output of the flip-flop is HIGH.
PIN 8(VCC SUPPLY):This pin connects the 555Timer to the positive power supply. the general purpose TTL 555 timers operates with voltages between 4.5v - 15v.
The 555Timer gets it name from the facts that there are three internally connected 5kohms resistors connected internally producing a voltage divider network between the supply voltage at pin 8 and ground (pin 1). the voltage across the series resistive network hold the negative inverting input of comparator (u2) at 2/3vcc and the positive non-inverting input of comparator (u1) at 1/3vcc.
The two comparators produce an output voltage that depends on the differences between it inputs which in turn is dependent on the charging and discharging of the external RC network.
The two comparators produce an output voltage that depends on the differences between it inputs which in turn is dependent on the charging and discharging of the external RC network.
555 timer Datasheets
USES
THE 555 Timer can be use for different applications by the addition of several external components.
1.Precision Timing
1.Precision Timing
2.Pulse Generation
3.Time Delay Generation
4.Pulse Width Modulation
5. Linear Ramp Generator
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