Digital multimeter project

Digital PIC18F multimeter is nowadays the most used measuring instrument for electrotechnical measurements.

For users, the advent of digital multimeters meant above all reliability and instrument for measuring all common electrical parameters. The design required the use of a minimum number of components at Maintaining good overvoltage protection.

The connection of the multimeter and the computer is realized today the most widespread USB bus. The communication is based on the HID standard for which it is possible use the standard system driver. The interconnection gives rise to new functions, such as the possibility of storing measured values values, displaying the course of the measured quantity or the possibility of long-term measurement displaying a graph of the measured quantity development.

To convert the analog signal to digital equivalent, software reference needs to be determined. Selecting a reference defines the range input voltage. Adding an external reference will limit the number of pins for connecting the analog signal on Software alignment can be selected right or left alignment. I have chosen a suitable microprocessor for application into USB multimeter. I designed circuit diagram and printed circuit board of USB-multimeter.

After I started USB communication and I wrote microprocessor software for voltage, current and resistance measurements. Furthermore, I created a control program that is designed to control measuring part and display of measured value. When comparing the designed multimeter with the exact Instek multimeter, I found that when voltage and current measurement is maximum error 0. I consider this fact great result. On the contrary, measurement of resistance using a current source is rather informative.

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For accurate measuring bridges are used today to measure resistance. A considerable disadvantage of the proposed multimeter is the magnitude of the input resistance when measuring Tension. An input resistance of k is a very bad value per voltmeter.

digital multimeter project

On the contrary the advantage of the proposed whole is the possibility of further extension of the management program, for example by: saving or reading the measured data, displaying the measured data in a graph, measuring extension temperature or even creating a simple version of the oscilloscope.

In this application, which if the link is relevant, as long as the button is pressed, the led light and the.

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We constantly work places which attracts lighting with RGB LEDs that are encountered in a variety of colors created by the. PIC16F84 made a beginning with a simple timer in the introduction to electronic. Old atari, commodore, amiga joystick you can use on your computer usb converter circuit circuit based on Atmel ATmega8-pin adapter does. MQ7-CO Sensor detection using that carbon monoxide alarm circuit PIC16F88 microcontroller based on the operating voltage 12v dc carbon monoxide detection.Electrical Academia.

Multimeter A multimeter, shown in Figure 1, is a device used to measure two or more electrical quantities. A multimeter can be used to measure electrical functions such as voltage, current, resistance, continuity and some are able to measure electrical frequency.

There are two main types of multimeters. One of the first and oldest multimeters is the analog meterFigure 2 and the other, now more widely used meter is the digital multimeter Figure 1. Analog meters are a multifunctional multimeter that operates based on electrical mechanical movement.

Analog meters use a printed linear or nonlinear background and a mechanical pointer. The pointer moves as a result of the flow of current through a built-in coil, the presence of electrical pressure, or the internal power source that is needed for resistance measurements.

The advantage of an analog meter is relatively small; however, it allows you to see small changes in current flow and a change in voltage in real time. Analog meters require great mathematical skills because you are required to make quick calculations based on the printed scale. Time used while calculating mathematical solutions while taking a reading with an analog meter could be better used to resolve other problems. A digital multimeter DMM is a multifunctional meter that displays its electrical quantitative values on an LCD screen.

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A digital multimeter much like an analog meter, it is able to read voltage, current, and resistance. What makes a digital multimeter differ from the analog meter is its ability to display measured electrical values quickly without any computations.

Because of its design, a processor can be built into the meter which allows the user to take measurements of frequency, the inductance of a coil, capacitance of a capacitor, and a host of other high functional electrical measurements.

When working with the scalable digital multimeter you need to have an idea of the value of voltage, current, or resistance that you are attempting to measure. Failure to observe these values will result in inaccurate readings and possible damage to the meter. The auto-ranging digital multimeter is more widely used due to its ease, high functionality, and quick display readings achieved without the user completing the calculations.

The following figure represents the digital multimeter block diagram with all the functional blocks. The auto-ranging digital multimeter DMM only requires you to choose your electrical quantity you are attempting to measure, make sure you are properly placing your leads into the correct terminals and then reading the LCD display. Auto-ranging digital multimeters allow technicians to spend more time getting to the root of a problem instead of switching and calculating. Testing for voltage is carried out to ensure the effectiveness of the electrical system.

Loads for example lights or motors that are designed to do the work need a nominal voltage to operate. Overvoltage will result in equipment failure and not enough voltage will result in the load not turn on. When testing voltage there is an expected voltage reading to look for. If the voltage reading is out of specifications then the problem can be found using the voltmeter to isolate the load and find if there is a problem with the source or the load.

digital multimeter project

Here is a step by step guide on how to use a multimeter to test for voltage:. Testing for current is used when there is no physical way to tell if a load is doing its job because there are no indicators or the load is located in a hazardous area.

10 Best Multimeters in 2020

It is important to understand a load consumes power which is measured in watts. Watts is calculated by multiplying volts by the amps. A digital multimeter is used to measure or give a good indication of current flowing.

Current can be tested in several ways; the most reliable procedure is using a clamp meter, shown in figure 4.The most important and expensive component in a meter is the movement : the actual needle-and-scale mechanism whose task it is to translate an electrical current into mechanical displacement where it may be visually interpreted. The ideal meter movement is physically large for ease of viewing and as sensitive as possible requires minimal current to produce full-scale deflection of the needle.

High-quality meter movements are expensive, but Radio Shack carries some of acceptable quality that are reasonably priced. It may be cheaper to purchase an inexpensive analog meter and disassemble it for the meter movement alone. Although the thought of destroying a working multimeter in order to have parts to make your own may sound counter-productive, the goal here is learningnot meter function.

I cannot specify resistor values for this experiment, as these depend on the particular meter movement and measurement ranges chosen.

First, you need to determine the characteristics of your meter movement. Most important is to know the full-scale deflection in milliamps or microamps. To determine this, connect the meter movement, a potentiometer, battery, and digital ammeter in series.

Adjust the potentiometer until the meter movement is deflected exactly to full-scale. Be very careful not to apply too much current to the meter movement, as movements are very sensitive devices and easily damaged by overcurrent. Most meter movements have full-scale deflection current ratings of 1 mA or less, so choose a potentiometer value high enough to limit current appropriately, and begin testing with the potentiometer turned to maximum resistance.

The lower the full-scale current rating of a movement, the more sensitive it is. After determining the full-scale current rating of your meter movement, you must accurately measure its internal resistance. To do this, disconnect all components from the previous testing circuit and connect your digital ohmmeter across the meter movement terminals.

Record this resistance figure along with the full-scale current figure obtained in the last procedure. Perhaps the most challenging portion of this project is determining the proper range resistance values and implementing those values in the form of rheostat networks. A simple rheostat network to produce In this position, the meter is a sensitive ammeter with a range equal to the full-scale current rating of the meter movement.

The shunt resistor R shunt necessary for a high-current ammeter function needs to be a low-resistance unit with a high power dissipation. To calibrate a home-made shunt resistor, you will need to connect the your multimeter assembly to a calibrated source of high current, or a high-current source in series with a digital ammeter for reference.

Use a small metal file to shave off shunt wire thickness or to notch the sheet metal strip in small, careful amounts.

digital multimeter project

The resistance of your shunt will increase with every stroke of the file, causing the meter movement to deflect more strongly. Build the multimeter circuit on a breadboard first while determining proper range resistance values, and perform all calibration adjustments there.

Radio Shack sells printed circuit boards that have the same layout as a breadboard, for convenience catalog Feel free to alter the component layout from what is shown. I strongly recommend that you mount the circuit board and all components in a sturdy box so that the meter is durably finished.

Despite the limitations of this multimeter no resistance function, inability to measure alternating current, and lower precision than most purchased analog multimetersit is an excellent project to assist learning fundamental instrument principles and circuit function.A digital multimeter is an indispensable tool for testing, diagnosing, and troubleshooting electrical circuits, components and devices.

The first digital multimeter was introduced in the lates, and has proven much more accurate and reliable than the old needle-based analog meters.

Digital Multimeter Shield for Arduino

Below are five common uses for your digital multimeter. Note that the instructions given here are applicable to most multimeters. However, the exact procedures and how the screen reads out might differ slightly based on the features and functions of your particular device.

Extreme safety precautions must be followed when taking electrical measurements. Before using a digital multimeter, be sure to read and fully understand the instructions and warnings outlined in the owner's manual. Before diving headlong into how to use your new multimeter, give Fluke's introductory articles into multimeters a read as well. They'll give you a solid rundown about what multimeter is as well as everything it can doand keep reading to get some tips from our of our favorite electricians.

Starting with the simplest, most basic test, use the voltage mode on your meter to check battery output. Most modern meters make this setup all but foolproof by also color coding the jacks. The black common probe goes into the black jack; the red probe goes in the red jack.

For example, a fully charged AA battery should have a reading of at least 1. And you can use your multimeter to test virtually any battery ranging from AAAs to car batteries. The test gives you a rough idea of whether the battery is good, shot, or needs to be charged. Then turn the rotary switch to Volts AC Vacwhich is also indicated by a wavy line on the dial. Push the tip of the red probe into the shorter hot of the two vertical slots on the outlet.

Insert the black probe into the longer slot neutral. A properly functioning outlet should produce to volts. Next, remove the black probe from the outlet—leave the red probe in place—and insert the black probe into the small, rounded hole ground below the two slots.

The reading should remain the same. Got a faulty ceiling light? First, turn off the power to the switch, remove the cover plate, and unscrew the switch from its wires. Before disconnecting the wires, label them or take a photo with your phone to ensure you reconnect them correctly. Loosen the switch terminal screws, unhook the wires from them, and remove the switch.

digital multimeter project

Set the resistance range to X1. Skip this step if your meter has auto-range you can tell you have an auto-ranging meter if you turn the dial to the Volts AC Vac setting, the word "auto" appears on the screen. Plug the black probe into the COM jack and the red probe into the red V jack.

To test a single-pole switch the simplest kind; it has two brass screws and one green screw.Learning about basic electronics and creating your own projects is a lot easier than you may think. You will then learn about schematic diagrams and how they are used to design and build circuits. And finally, you will put this information to use by creating your first basic circuit.

Before you get started, make sure your electronic workbench is properly set up.

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The most popular option is to use clear plastic storage boxes for storing parts. Breadboards are an essential tool for prototyping and building temporary circuits. These boards contain holes for inserting wire and components. Because of their temporary nature, they allow you to create circuits without soldering. The holes in a breadboard are connected in rows both horizontally and vertically as shown below. Check out this post for more info on how to use a multimeter. A battery holder is a plastic case that holds batteries from 9V to AA.

Test leads are great for connecting components together to test a circuit without the need for soldering. The advantage of these over normal screwdrivers is the precision tips of each driver.

These are very handy when working with electronics that contain tiny screws. When working with electronics, it seems you never have enough hands to hold everything.

This is where the helping hand 3rd hand comes in.

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Great for holding circuit boards or wire when soldering or tinning. Heat shrink has been called the duct tape of electronics and comes in handy in a wide variety of applications. These wires are used with breadboard and development boards and are generally AWG solid core wire. Jumper wires can have male or female ends depending on how they need to be used. To do this, a soldering iron is the tool you would use. You can choose leaded or lead-free solder in a few diameters.

Now its time to talk about the different components that make your electronic projects come to life. Below is a quick breakdown of the most common components and functions they perform. Switches can come in many forms such as pushbutton, rocker, momentary and others.

Their basic function is to interrupt electric current by turning a circuit on or off. Resistors are used to resist the flow of current or to control the voltage in a circuit. The amount of resistance that a resistor offers is measured in Ohms. A variable resistor is also known as a potentiometer. These components can be found in devices such as a light dimmer or volume control for a radio. When you turn the shaft of a potentiometer the resistance changes in the circuit.

These are often found in exterior lights that automatically turn on at dusk and off at dawn. Capacitors store electricity and then discharges it back into the circuit when there is a drop in voltage. A capacitor is like a rechargeable battery and can be charged and then discharged. A diode allows electricity to flow in one direction and blocks it from flowing the opposite way. A light-emitting diode is like a standard diode in the fact that electrical current only flows in one direction.

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The main difference is an LED will emit light when electricity flows through it. Inside an LED there is an anode and cathode. The longer leg of the LED is the positive anode side.There are many different multimeters available on the market inand each one has its own strengths and weaknesses.

Related: Tire Inflators for your Car. While the Craftsman 34 Digital Multimeter may not be quite as precise and accurate as a Fluke multimeter or other professional electrical tool, it is an excellent choice for new users thanks to its impressive affordability and wide range of functions.

This offers more than enough usability and functionality for most household DIY users, and is well built and durable, with a rugged outer rubber case to protect from impacts from accidents such as dropping, ensuring that this model of multimeter remains fully functional at all times, even when used heavily in poor conditions for extended periods of time.

Affordable and accessible, the Craftsman 34 Digital Multimeter is a great entry-level option for more casual users who just need regular household measurement tools for DIY work. Featuring professional quality design and build quality, the Fluke Electricians True RMS Multimeter is designed for use by electricians and serious DIY users in search of a high quality, advanced tool.

This premium multimeter may not come with a holster for security, but this is a minor price to pay for such a high-performance multimeter loaded with advanced features.

Its True RMS technology allows for easy, safe reading of non-linear loads with a high level of accuracy, while the backlit LED screen makes working in poor lighting and visibility conditions far easier than most competing models. This is a versatile and durable multimeter that operates comfortably in a wide range of temperatures, maintaining its high performance in even the worst conditions.

Offering high performance in a professional quality package, the Fluke Electricians True RMS Multimeter is among the best multimeter options for serious users and professionals in need of a great, high-performance tool.

The Cen Tech Digital Multimeter is a compact and accessible portable multimeter that offers a high level of basic functionality, with 7 different main measurement functions. Its large LCD display offers bold, clear numbers, making it exceptionally easy to read, while the simple single dial control system is easy to use in all situations.

The compact body of this multimeter is a significant selling point, as the whole thing is roughly credit card sized, making it incredibly easy to fit into any toolkit and carry around, ensuring that you always have a multimeter tool to hand for use in any situation in which you might need to measure an electrical current for any reason.

Functional and easy to use, the Cen Tech Digital Multimeter is an excellent choice for almost any user. Its compact and portable design makes it easy to use on the go, and easy to transport in any situation. The Etekcity Digital Voltage Tester Meter is one of the smallest and most easily affordable multimeter options out there.

This is a high value, accessible option that provides measurement of a full ten different functions, although it is not appropriate for all current types. The portability of this miniature multimeter is a significant selling point, as it is small enough to be easy to carry with you at all times for on the go electrical measurement at any time. As an added bonus, it also incorporates a durable rubber sleeve for protection, helping to keep the multimeter safe.

This is an important element, as the build quality of the Etekcity Digital Voltage Tester Meter is a little on the fragile end, meaning that any added protection available is worth taking full advantage of.

Simple and affordable but impressively high performance, the Etekcity Digital Voltage Tester Meter is a great entry-level option that still provides enough performance for professional use.

Despite its small size, the Extech EX Autoranging Mini Multimeter offers impressive functionality, making it an excellent choice for on the go electrical tasks. This best compact multimeter includes a built-in non-contact AV voltage detector, allowing you to obtain accurate AC voltage readings without any risk to yourself from contacting current, keeping you safe and comfortable at all times.

As an added bonus, this multimeter includes a thermometer for easy reading of temperatures with a high level of accuracy.

The final important feature of this multimeter is its protective rubber holster, which offers a high level of resistance to both electrical shocks and impact from accidents and dropping, keeping this multimeter in perfect working condition for as long as possible even when used very heavily.

These cover all of the major required electrical testing functions for DIY household or professional electrical measurement situations, with each element offering valuable features for testing.

The NCVT 1 easily detects standard voltage levels for circuit breakers, cords, cables, outlets, wires, switches, and lighting fixtures. The MM tests continuity using simple and easy to read visual and audible indicators for a simple user experience, while the RT plugs easily into most standard electrical receptacles to detect the most common wiring problems found in outlets.

The versatility of the selection of testing devices included in the Klein Tools Electrical Test Kit makes this a valuable and flexible choice for use in a wide range of different electrical testing situations. The Crenoca MSD Auto Ranging Digital Multimeter is an auto-ranging tester, automatically detecting the required range of voltages to measure without needing manual indication of the required voltage range for an easier user experience.

As a further usability feature, this multimeter features a large LCD display with strong backlight power, making it easy to read and clear even in poor visibility and low light conditions. The Crenoca MSD Auto Ranging Digital Multimeter also features a range of additional functions for added versatility, including built-in overload protection for safety and security, and a data hold and maximum value hold functionality, offering memory of the detected values for future reference without the need for manually writing the numbers down.

Offering a wide range of valuable functions, the Crenova MSD Auto Ranging Digital Multimeter is a versatile and valuable multimeter that offers a high level of functionality ideal for almost any user. A powerful and versatile multimeter, the AstroAI Digital Multimeter incorporates a range of helpful features that allow it to perform several valuable functions, as well as some handy durability elements. This multimeter may be unable to test AC voltage, but it can accurately measure voltage, DC current, resistance, diodes, continuity, and other functions.This instructable describes a shield, which converts "Arduino" board in a digital multimeter DMM.

It can work in three modes:. The second mode does not require the presence of LCM, what makes the shield very cheap. The "Arduino" based DMM has the following functions:. I thought to add these warnings at the end, where the conclusions should be, but I have changed my mind because of the importance of this step.

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Before starting the copying of the design and doing some measurements the following things should be kept always in attention. Dangerous voltages could appear at the shield nodes, connections and parts. As the shield is designed in the presented implementation, it can be used for measuring of voltages until V. These voltages are dangerous for the life!!! Even voltages close to 30 V in some cases can cause death. For this reason, all requirements concerning the work with high voltages must be met:.

You should use only insulated leads. You should avoid touching of the shield parts especially the banana socket for voltage measurements and the input resistor. You should keep your table clean - no metal parts or instruments shall be placed close to the shield because they can create short circuit between the shield parts.

You should not touch any of the banana sockets and plugs during high voltage measurements. The banana socket for the voltage measurement is not insulated in any way and touching it during operation can have deadly results!!! I would like to thank the user "granz" see the commentswho reminded us about the following: When using the "Arduino" based DMM connected to the computer, you should be aware of that the ground potentials of the DMM is the same as the ground potential of you PC, and you should measure voltages and currents of device or unit, which have the same ground potential.

In other case you risk to damage both - you computer and your device. The main idea of the project was to create a shild for "Arduino", which can be used for voltage and current measurements.

Starting the design, I decided to keep the circuit as simple and cheap as possible. During the design phase, I have found that I can implement some additional useful functions without big efforts and investments. Because I have used dual opamp chip and one of the embedded amplifiers was used for the ampere meter, I was looking for a way, how I could use the second one. This required some additional parts, but have added more functionality to the board.

Although the main two functions could be done very precise especially with final software trimmingthe additional functions have some lack of accuracy. The reason for that will be explained further. Keep reading There are some simple solutions, which can drastically improve also this accuracy, but they require some additional parts and are matter of possible feature project. The schematics and the PCB board layout are presented on the pictures.

Remarks on the schematic:. The " Eagle" design files are attached to the project and are available for download and free use. The Gerber files prepared for PCBway fab with very cheap and high quality production are also available for download.

The schematic may look quite complicated. For that reason I will try to explain how the different functions work, separating the circuit in sub-blocks, simplifying them and showing how the calculations were done. Let's start with the voltmeter. On the picture, its simplified schematic can be seen. Three voltage dividers for the three ranges can be alternatively formed by use of switches controlled by the "Arduino" board.

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Only one switch is closed during the voltage measurement. They have typical Ron around Ohms, which does not influence a lot the accuracy for the ranges V, V. For the range V, their Ron is taken into account, when calculating the voltage divider ratio. The Zener diode is used to clamp the Vmeas potential the voltage applied to the analog input A0 of the "Arduino" at 5.