1. WATER LEVEL CONTROLLER USING 555 TIMER
By,
Department of TCE/ECE JNNCE , Shimoga

2. OBJECTIVE:
Automatic Control of AC Motor
Thus Preventing overflow from
Over Head Tank.

3. OVERVIEW :
AC MOTOR M
OVER HEAD TANK
Upper
CIRCUIT BOARD
Lower
GND

4. CIRCUIT BOARD BLOCK DIAGRAM:
555 TIMER IC
Input From OHT
DRIVER
RELAY

5. CIRCUIT DIAGRAM:

6. Introduced in 1972 by Hans Camenzind
ABOUT THE 555 TIMER IC
Introduced in 1972 by Hans Camenzind
at 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 resistors
in 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 GND
4- 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 mA
3) 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.

13. CIRCUIT DIAGRAM:

14. 555 ANALYSIS : + -

15. TRUTH TABLE : (SR FLIP FLOP)
SET(S)
RESET(R)
Action
HOLD STATE 1
RESET(0)
SET(1)
NOT ALLOWED + -
WATER CONTROLLER TRUTH TABLE :
Pin 2
Pin 6
Output
Low
High
No change
Not 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:
PARTICULARS
QUANTITY IC
NE555 1
IC-BASE
8 PIN
RESISTORS
1M ,10K
2,2
CAPACITORS
1uF , 0.01uF
1,1
DIODE
1N4007
TRANSISTOR
BC548,SL100
GENERAL PCB
2*3 INCH
DC JACK
FEMALE
12V ADAPTER
SMPS
PCB RELAY
12 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.