NE 555 Timer chip is a very popular and versatile IC. Many applications are built around this chip. application. The chip has a accurate time control circuit. The time delay can be generated by using external resistor and capacitor so that the duty cycles are adjustable. The timing accuracy can be achieved between microseconds and hours.
Simple Block diagram of 555 timer IC
The Threshold level is 2/3 of the VCC and trigger level is 1/3 of VCC. When the trigger input is below the trigger level voltage then Flip-Flop is set and output goes high When trigger input and threshold input is more than trigger and threshold levels then Flip-Flop output is reset and output is low. Reset pin can override all inputs.
Water Level Controller Hardware:
Schematic for Water Level Controller Ckt.
The components required for Water Level Controller Ckt
1. NE 555 IC
2. 1k Resistor 1/4 W
3. 4.7K Resistor 1/4 W
4. 10 M Resistors
4. Relay 5V or 6V
5. Leds
6 Switch for Input supply
7. Water Level Sensor (SS contact type switch sensor,Float level sensor,Magnetic Switch Sensor,eletrodes can be used as the level sensors).
8. 5V or 6V Power Supply input
Set-up
The level sensors(Low and high ) are inserted into the water tank and 5v is applied to the water.
The Water levels are indicated by Leds. The Low and High level sensors are connected to trig and threshold pins of 555 Timer. The output pin of 555 chip drives transistor which drives the relay. The activation voltage (AC or DC) is connected to the common pin of Relay. The NO pin of relay Drives the water pump.
Power supply switch is used to power up the ckt which is indicated by LED near the switch.
The
Working of the Ckt.
The switch near power Supply input is closed to power-up the ckt. The led is on to indicate the power supply is on. When the Water tank is dry, both inputs levels at threshold and trigger pins are low as both pins pulled down to ground with 10 M Resistors. This drives the output pin of 555 timer to high driving
relay on and turning the water Pump on. As the water level in the tank touches low level sensor then corresponding led turns on and 5v is connected to the trigger pin. When water level crosses high level sensor the corresponding Led turns on and 5v is applied to the threshold pin of 555 timer.As the threshold input voltage becomes more than 2/3 of Vcc,the output pin turns low, turning the Water Pump off.
The Simulation of Water level Controller is explained in this YouTube video with help of Circuit Simulator Software as shown below.