31-07-2013, 03:00 PM
WATER LEVEL INDICATOR USING 7 SEGMENT
WATER LEVEL.pdf (Size: 668.22 KB / Downloads: 162)
DESCRIPTION
Most water level indicators for water tanks are based upon the number of LEDs that glow to
indicate the corresponding level of water in the container. Here we present a digital version of
the water level indicator. It uses a 7-segment display to show the water level in numeric form
from 0 to 9.
The numeric water indicator circuit works off 5V regulated power supply. It is built around
priority encoder IC 74HC147 (IC1), BCD-to-7-segment decoder IC CD4511 (IC2), 7-segment
display LTS543 (DIS1) and a few discrete components.
When the water tank is empty, all the inputs of IC1 remain high. As a result, its output also
remains high, making all the inputs of IC2 low. Display LTS543 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 IC1 become low and its output goes low to
make all the inputs of IC2 high. Display LTS543 now shows ‘9,’ which means the tank is
full.Assemble the water level indicator circuit on a general-purpose PCB and enclose in a box.
Mount 7-segment LTS543 on the front panel of the box. For sensors L-1 though L-9 and
ground, use corrosion free conductive-metal (stainless-steel) strips.
COMPONENT DISCRIPTION
IC CD4511:
CD4511BMS is a BCD-to-7-Segment latch decoder drivers constructed with CMOS logic and
n-p-n bipolar transistor output devices on a single monolithic structure.
These devices combine the low quiescent power dissipation and high noise immunity features
of Intersil CMOS with n-p-nbipolar output transistors capable of sourcing up to 25mA.
This capability allows the CD4511BMS types to drive LED’s and other displays
directly.Lamp Test (LT), Blanking (BL), and Latch Enable or Strobe inputs are provided to
test the display, shut off or intensity modulate it, and store or strobe a BCD code,
respectively.Several different signals may be multiplexed and displayed when external
multiplexing circuitry is used.
These devices are similar to the type MC14511.The CD4511BMS is supplied in these 16-lead
outline packages
GENERAL DESCRIPTION
The 74HC/HCT147 are high-speed Si-gate CMOS devices and are pin compatible with low
power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no.
7A.
The 74HC/HCT147 9-input priority encoders accept data from nine active LOW inputs (A0 to
A8) and provide a binary representation on the four active LOW outputs (Y0 toY3).
A priority is assigned to each input so that when two or more inputs are simultaneously active,
the input with the highest priority is represented on the output, with input line A8 having the
highest priority.
The devices provide the 10-line to 4-line priority encoding function by use of the implied
decimal “zero”. The “zero” is encoded when all nine data inputs are HIGH, forcing all four
outputs HIGH.
TRANSISTORS
A transistor is a semiconductor device used to amplify and switch electronic signals and
electrical power. It is composed of semiconductor material with at least three terminals for
connection to an external circuit. A voltage or current applied to one pair of the transistor's
terminals changes the current through another pair of terminals. Because the controlled
(output) power can be higher than the controlling (input) power, a transistor can amplify a
signal. Today, some transistors are packaged individually, but many more are found
embedded in integrated circuits.
The transistor is the fundamental building block of modern electronic devices, and is
ubiquitous in modern electronic systems. Following its development in the early 1950s, the
transistor revolutionized the field of electronics, and paved the way for smaller and
cheaper radios, calculators, and computers, among other things.
Transistor as a switch:
Transistors are commonly used as electronic switches, both for high-power applications such
as switched-mode power supplies and for low-power applications such as logic gates.In a
grounded-emitter transistor circuit, such as the light-switch circuit shown, as the base voltage
rises, the emitter and collector currents rise exponentially. The collector voltage drops
because of reduced resistance from collector to emitter. If the voltage difference between the
collector and emitter were zero (or near zero), the collector current would be limited only by
the load resistance (light bulb) and the supply voltage. This is called saturation because
current is flowing from collector to emitter freely. When saturated the switch is said to be on.
CONCLUSION
This is an effective system for knowing the level of water in the tank. This project can also be
successfully implemented in minor and major projects for knowing the level of water.