Experiment No. 1 Project Report on Analog Multimeter (MIYAMA M-385) Rommel Areola BSEE 3-1 August 4, 2012 Project Summary This project is a laboratory report on the principles of operation, construction, calibration, and evaluation of an electrical analog multimeter or Voltmeter-Ohmmeter-Milliammeter(VOM). The multimeter model used in this project is MIYAMA M-385. Parts of the design on the schematic diagram, PCB layout and component placement are modified by the researcher, thus, it may vary from the original overall design of MIYAMA M-385 multimeter. Introduction The multimeter is an essential tool for engineers, especially those specializing in the field of electricity. Such testers may vary in design and purpose, and may include more than three parameters of measurement. It is then a need for electrical engineering students to study how these testers operate, how to repair and calibrate them, and how to use them properly. This paper deals with these studies about multimeters. Purpose Page 1 of 16
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Experiment No. 1
Project Report on
Analog Multimeter (MIYAMA M-385)
Rommel Areola
BSEE 3-1
August 4, 2012
Project Summary
This project is a laboratory report on the principles of operation, construction, calibration, and
evaluation of an electrical analog multimeter or Voltmeter-Ohmmeter-Milliammeter(VOM). The
multimeter model used in this project is MIYAMA M-385. Parts of the design on the schematic
diagram, PCB layout and component placement are modified by the researcher, thus, it may vary
from the original overall design of MIYAMA M-385 multimeter.
Introduction
The multimeter is an essential tool for engineers, especially those specializing in the field of
electricity. Such testers may vary in design and purpose, and may include more than three
parameters of measurement. It is then a need for electrical engineering students to study how these
testers operate, how to repair and calibrate them, and how to use them properly. This paper deals
with these studies about multimeters.
Purpose
The project aims to explain the assembly and construction of a typical analog electric multimeter
and how it works. It may also serve as a reference for fellow researchers interested in making their
own multimeters.
Scope
The efficiency and general use of the project is confined to the nature of the multimeter circuit
design. And since the project is a measuring device, the use of accurate, less tolerant (resistors used
in this project are ±1% tolerant), and appropriate electronic components must be considered.
Page 1 of 12
Project Report on Analog Multimeter
Areola, RA
The model used for this project is MIYAMA M-385 that includes 4 ranges for AC Voltmeter, 6 ranges
for DC Voltmeter, 4 ranges for DC Milliammeter, and 4 ranges for Ohmmeter. The entire project and
research body is limited only to the mentioned parameters.
This paper will discuss the construction, design, and evaluation of the multitester, which is prepared
and built within a two-week period.
Discussion
Methodology
This section of the project paper discusses the step-by-step procedures followed in making the
MIYAMA multitester.
Electronic Components
Page 2 of 12
Project Report on Analog Multimeter
Areola, RA
Equipments and Materials
2 1.5V AA Battery
1 9V Battery
Project Casing
Soldering Iron
Soldering Lead
Soldering Paste
General Procedures
The project is accomplished by following these steps. First, decide what specific design of multimeter
and measurement parameters you want to include. Then purchase all components and other
materials to be used. If the design needs PCB etching, consult Printed Circuit Boards-Design,
Fabrication, and Assembly by R.S. Khandpur. Next, place the components on the board. Be cautious
in reading the ratings of each component.
When all the components are placed on the board, cut all portruding component leads, leaving only
about 3mm (cutting the leads may also be done after soldering). Then solder each component
properly to the board. Avoid solder bridges and poor connection between board and component, for
these may result in a shorted circuit or malfunction. Check for any misplaced component before
assembling the board to the project casing.
Flow Chart of Procedures
For a better understanding of the procedures, the table below shows the chronological arrangement
of steps.
Design lanningDDDDFFF
Figure 1: Flow Chart of Procedures
Page 3 of 12
Design Planning Purchase of Materials PCB Etching
Component Placement
Casing Assembly
Finalizing Soldering
Evaluation
Project Report on Analog Multimeter
Areola, RA
Printed Circuit Board Layout
The tables below show the PCB layout design and component placement of the multitester. The
layout design shows how the PCB must look like after etching (ready-made etched PCB’s are also
available in market). While the component placement assists the researcher on how the
components are to be placed and positioned on the PCB.
Figure 2: PCB Design
Figure 3: Component Placement
Page 4 of 12
Project Report on Analog Multimeter
Areola, RA
Project Schematic Diagram
The following table shows the MIYAMA M-385 multitester schematic diagram. Before evaluation,
the researcher must conform to the schematic diagram to prevent malfunctions.
Figure 4: Project Schematic Diagram
Test and Evaluation
This part presents the multitester evaluation procedures and basic statistical treatments used.
Initial Test
After the project was assembled, initial tests were conducted, like applying appropriate loads,
current, and voltage to each corresponding range to check whether the meter and each range
works. All three measurement parameters (Voltmeter, Milliameter, Ohmmeter) worked well with
this test.
Page 5 of 12
Project Report on Analog Multimeter
Areola, RA
Accuracy Tests
Since the project is a measuring device, accuracy of the reading must be given due emphasis. It is in
this light that the researcher devised the following formula for getting the accuracy of the meter:
Accuracy=100−[( units of deviationunits applied )×100]The following tables show the reading accuracy of each of the ranges of the 3 measurement
parameters (ACV, DCV, DCmA, and Ohmmeter).
AC Voltmeter
Table 1: AC Voltmeter Accuracy Test
Range Voltage Applied Reading Accuracy
1000V 230V 240V 95.65%
250V 230V 246V 93.04%
The above results were gathered by applying 230V household line into the first two ranges of the
ACV. Voltage sources lower than 230V may be used to test the lower ranges. The above test shows
that the ACV is in good and accurate condition.
DC Voltmeter
Table 2: DV Voltmeter Accuracy Test
Range Voltage Applied Reading Accuracy
2.5V 1.5V 1.7V 80%
10V 9V 9.3V 96.86%
50V 24V 25V 95.83%
250V 24V 24V 100%
In this test, a variable DC power supply ranging from 3-24V is used to obtain the results above. It is
important to note that power supplies supply a bit higher voltage than its rated voltage. And
accuracy of the meter depends also on the compatibility of the range and the applied unit. For
Page 6 of 12
Project Report on Analog Multimeter
Areola, RA
example, an exact amount of 24V is hardly discernible in the 0-250V scale. The researcher may want
to use more compatible voltage source with that of a specific range.
DC Milliameter
Table 3: DC Milliammeter Accuracy Test
Range Current Applied Reading Accuracy
250mA 230mA 238mA 96.53%
25mA 25mA 25mA 100%
This test used small DC cells with the rated amperage as indicated in the table. The other DCmA
ranges were not tested because current sources of those ranges are not available.
Ohmmeter
Table 4: Ohmmeter Accuracy Test
Range Load Applied Reading Accuracy
10,000 44kΩ 4.4x10,000=44kΩ 100%
1,000 44kΩ 43x1,000=43kΩ 97.73%
100 1kΩ 10.2x100=1020Ω 98%
10 1kΩ 102x10=1020Ω 98%
1 200Ω 188x1=188Ω 94%
The test above was conducted by measuring different values of color-coded carbon resistors (44kΩ,
1kΩ and 200Ω). All used resistors are rated at ±1% tolerance. Considering this, all of the achieved
readings fall in the rated range of the resistors. Which means the project’s ohmmeter functions well
and measures accurately.
Evaluation and Recommendations
The figures presented above makes conclusive marks that the multimeter is in good electrical
condition and measures in high accuracy. All went well within the project, only except the
ohmmeter. The researcher compels the readers and researchers to enhance and improve the
multimeter circuitry, like adding an extra parameter of measurement (e.g. hFe tests, decibelmeter,
Page 7 of 12
Project Report on Analog Multimeter
Areola, RA
frequency meter, etc.), or a buzzer circuit for continuity tests. The mathematical treatments used in
this paper may also be improved to achieve better results.
References
Buchsbaum, Walter. Buchsbaum’s Complete Handbook of Practical Electronics Reference Data.
Englewood Cliffs, NJ: Prentice Hall, Inc., 1975.
Ganic, Ejup, and Hicks, Tyler. McGraw-Hill Handbook of Essential Engineering information and Data.