Abstract
An Arduino UNO microcontroller based digital voltmeter has been designed and
developed with liquid crystal display and voltage range indicator. A regulated low voltage
power supply circuit (5 volt) has been developed to power up Arduino microcontroller.
Arduino senses the input voltage, converts the analog voltage into digital value and displays
the value through a liquid crystal display. By turning on LED lights, the Arduino calculates
the value and indicates the voltage range. A green LED shows a low-voltage range of 0.1 to 5
volts, which can be used to power low-voltage integrated circuits such the LM741 and
CA3140. A yellow LED represents a mid-voltage range of 6 to 50 volts, but a red LED shows
a voltage more than 50 volts, which can be dangerous and should be avoided when using
small integrated electronic circuits.
Introduction
Voltage is one of the most basic factors in any electrical or electronic circuit; it is defined as
the force that compels charged electrons to move in an electrical circuit. The voltage at which
an electrical gadget operates is critical. To function properly, electronic devices must be
connected to the necessary operating voltages. Connecting a low-voltage electrical equipment
to a high-voltage supply can damage or even burn it out. As a result, it is necessary to
measure the provided voltage before attaching it to the circuit. The potential difference
between two locations in a circuit is measured with a Voltmeter or Voltage Meter. Voltmeters
are essential pieces of equipment for any type of electrical circuit functioning. Both AC and
DC voltages are measured with them. Analog voltmeters and Digital voltmeters are the two
types of voltmeters available. The movement of a pointer across a scale on an analogue
voltmeter is proportional to the voltage detected. A digital voltmeter is a voltage-sensitive
gadget that measures AC or DC voltage and displays the value in numeric form rather than
using a pointer. A digital voltmeter can be built using a microcontroller. The Arduino UNO is
a microcontroller board based on the ATmega328P microcontroller from Microchip. The
board has digital and analogue input/output (I/O) pins that can be used to connect to a variety
of devices, sensors, and other circuits. The purpose of the project was to create a low-cost
smart voltmeter for use in an electronics or physics lab.
Design Consideration:
The main part of the proposed system is Arduino UNO R3 microcontroller. Other parts of the developed
system are: low voltage power supply, voltage Divider network, liquid crystal display and voltage
transformer(zmpt101b) for ac voltage measurement.
Voltage power supply circuit
A low voltage well-regulated power supply of around 5 volt is required to power up the Arduino
microcontroller. Here a low voltage power supply circuit was developed to provide 5 volt regulated dc power
supply. For ac main power was collected from 220-volt ac line. A step-down transformer sensor zmpt101b
was used to step the voltage down within the limiting range of Arduino(5v).
Display Circuit
For displaying the measured voltage, a (16x2) liquid crystal display was employed which can show the analog
AC or DC voltage in digital way. The LCD is a electrically modulated optical device that uses the light
modulating properties of liquid crystal. The LCD display is more convenient to connect and configure with
Arduino which can display wide range of numerical value with associated data.
Signaling Conditioning:
Voltage Sensor Module:
AC:
DC:
In case of dc our voltage divider network is acting as sensing module. We have designed the network for 30volt dc range and used resistor values accordingly. Then the output of voltage divider network is given to
analogue input pin which is between 0-5 volt it is then mapped by Arduino between 0-1023 bits according to
incoming voltage like 1023 bits is assigned for maximum 5 volts and 0 for o volts.
Block Diagram:
Figure 2: Block diagram of the proposed system
Programming:
Results and Discussions:
The presented work has been planned and done in step-by-step process in a systematic way. At first
we planned about the system and then developed different small parts of this system like low voltage power
supply circuit in order to power up the microcontroller, voltage sensor circuit to senses the voltage and converts
the ACvoltage into DC voltage. A liquid crystal display was used to display the result besides we used three
types of LED to indicate the voltage range. Finally we combined different parts of the system.
The developed system is calibrated with other voltage measuring instruments and the data collection for both
low voltage (0v-5v) and medium voltage (6v-15v) are given below:
Conclusion
The complete system has been designed, developed and tested with „SAKO DC POWER SUPPLY‟
and „SANWA DIGITAL MULTIMETER‟. Here a regulated low voltage power supply (5 volt) has been
developed to power up Arduino microcontroller. Arduino senses the input voltage, converts the analog voltage
into digital value and displays the value through a liquid crystal display. The developed system is easy to
operate and reliable. It has been designed using the components that are readily available in the local market
andthe cost of the developed system is very less than the price of readymade portable voltage meter.