In this post we are going to learn how to design Inductive Water Level Indicator with Display. Most water level indicators are based upon the number of LEDs that glow to indicate the corresponding level of water in the container. But here we have designed Numeric Water Level Indicator using IC 74HC157 & CD4511. It is a digital version of the water level indicator using a 7-segment display to show the water level in numeric form from 0 to 9.
1. 5V Power Supply 2. 74HC147 IC (equivalent IC 74LS147) 3. CD4511 IC (equivaent IC 74HC4511) 4. Common Cathode 7 segment Display 5. Transisitor BC547 - 4 6. Resistor 560K - 10 7. Resistor 12K - 4 8. Resistor 33k - 4 9. Water Container
Circuit Diagram: Inductive Water Level Indicator with Display using IC 74HC157 & CD4511
Circuit Explanation & Working:
The numeric water indicator circuit works off 5V regulated power supply. It is built around priority encoder IC 74HC147 & BCD-to-7-segment decoder IC CD4511 & common cathode 7-segment display.
When the water tank is empty, all the inputs of 74HC147 remain high. As a result, its output also remains high, making all the inputs of CD4511 low. Display at this stage shows ‘0,’ which means the tank is empty. Similarly, when the water level reaches L-1 position, the display shows ‘1,’ and when the water level reaches L-8 position, the display shows ‘8.’ Finally, when the tank is full, all the inputs of 74HC147 become low and its output goes low to make all the inputs of CD4511 high. Display now shows ‘9,’ which means the tank is full.
It is recommended to use stainless steel wire without any corrosion for dipping into water, else you may not get desired result at display.
The container should be wired like this as shown in the figure below.
Result shown when dipped into water from number 0 to 9: