6 Introduced in 1972 by Hans Camenzind ABOUT THE 555 TIMER ICIntroduced in 1972 by Hans Camenzindat Signetics Corporation. Low cost , stable , low power.Manufactured 1 billion units / year .8 pin mini DIP-8 pack.Includes 25 Transistors ,2 diodes and 15 resistorsin silicon chip.Used in timer , pulse generation and Oscillator applications .
7 Pin Details:1 – GND : Ground, low level (0 V)2 – TRIGGER : Detects 1/3Vcc, Output high. Pin controls over Pin 6.3 - OUTPUT :This output is driven to approximately V below +V cc or GND4- RESET :A timing interval may be reset by driving this input to GND
8 5 – CONTROL : Control access to the internal 5 – CONTROL : Control access to the internal voltage divider (by default, 2/3 VCC).6 – THRESHOLD : The interval ends when the voltage at THRESHOLD is greater than at CONTROL.7 - DISCHARGE : Open collector output; may discharge a capacitor between intervals.8- VCC : Positive supply voltage.( 3 to 15V)
9 Specifications of NE555: 1) Supply Voltage : 3 to 15 V 2) Supply Current : 3 to 15 mA3) Output Current : 200mA (MaX)4) Power Consumption : V
10 Modes of Operation:Astable : Free Running mode, used as oscillator ,provide time delay, adjust duty cycle.2) Monostable : "one-shot" pulse generator.Applications include timers,bounce free switches.3) Bistable : Basic flip-flop , Schmitt trigger.
15 TRUTH TABLE : (SR FLIP FLOP) SET(S)RESET(R)ActionHOLD STATE1RESET(0)SET(1)NOT ALLOWED+-WATER CONTROLLER TRUTH TABLE :Pin 2Pin 6OutputLowHighNo changeNot Valid
16 *When Water Below LOWER LEVEL : Comparator 1 = high Comparator 2 = Low SR FLIP FLOP = SET (1) , Q bar ( OUTPUT ) = Low (DRIVES THE RELAY) *When Water Level Reaches UPPER LEVEL: Comparator 1= Low Comparator 2= High SR FLIP FLOP = RESET (0) , Q bar (OUTPUT) =High ( RELAY OFF)
17 WORKING ANALYSIS:MOTOR SWITCHES “OFF”MOTOR SWITCHES “ON”
18 RELAY : An Electromagnetic Switch Relay Open :Common - Normally closed (NC)Relay Closed :Common – Normally open (NO)
19 LIST OF COMPONENTS REQUIRED: PARTICULARSQUANTITYICNE5551IC-BASE8 PINRESISTORS1M ,10K2,2CAPACITORS1uF , 0.01uF1,1DIODE1N4007TRANSISTORBC548,SL100GENERAL PCB2*3 INCHDC JACKFEMALE12V ADAPTERSMPSPCB RELAY12 V
20 An Astable Circuit has no stable state - hence the name "astable" An Astable Circuit has no stable state - hence the name "astable". The output continually switches state between high and low without any intervention from the user, called a 'square' wave.This type of circuit could be used to give a mechanism intermittent motion by switching a motor on and off at regular intervals. It can also be used to flash lamps and LEDs, and is useful as a 'clock' pulse for other digital ICs and circuits.
21 A Monostable Circuit produces one pulse of a set length in response to a trigger input such as a push button. The output of the circuit stays in the low state until there is a trigger input, hence the name "monostable" meaning "one stable state
22 A Bistable Mode or a Schmitt Trigger, has two stable states, high and low. Taking the Trigger input low makes the output of the circuit go into the high state. Taking the Reset input low makes the output of the circuit go into the low state. A push button would be placed at each end of the track so that when one is hit by the train, it will either trigger or reset the bistable.