PRACTICE 1
USE OF THE OHMMETER, VOLTMETER AND AMMETER IN MEASUREMENTS OF D.C. SUBJECT: CIRCUITS FUNDAMENTAL ANALYSIS Students:
Ugalde López Eduardo Zúñiga Díaz Ángel Ángel
Teacher: Santillán Luna Raúl Team 8 Group 1CV1
Students learn to use correctly measuring instruments such as the digital voltmeter, digital ohmmeter and the digital ammeter.
1 Digital Multimeter
1 Breadborder
1 Variable Power Supply
1 Resistor of 1KΩ to ¼ of watt
4 Tips banana-caiman
1 Resistor of 560Ω to ¼ of watt
2Tips caiman-caiman
1 Resistor of 680 Ω to ¼ of watt 1 Resistor of 330Ω to ¼ of watt Wires to connection
These tools help us keep circuits and equipment in optimal performance based on equations and comparisons with respect to the flow of electricity. The parameters that distinguish the use of measuring instruments are: -The intensity is measure by Ammeters. -The tension is measure by voltmeters. -The resistive capacity is measure by Ohmmeters. The Multimeter is a measure instrument that combines all the functions of the three above mentioned. Electrical measurements are made using equipment specially designed depending on the nature of the current; that is, if alternative, continuous or pulsating. The instruments are classified by the parameters of voltage, voltage and current. Thus, we can state measuring instruments such as ammeter or current intensity unit. The voltmeter as tension unit, the ohmmeter as resistance unit and multimeter as multiple measurement units.
Figure 1. Digital Multimeter
-You need to connect in series with the circuit. -It should be an approximated intensity to be measure because if is greater than the scale of ammeter , it can damage. Therefore the intensity must be less than the scale of the ammeter.
Figure 2. Example of how to connect the ammeter to measure the intensity.
-You need to connect in parallel with the circuit, taking into account the polarity if is S.C. -It should be an approximate measure voltage in order to use appropriate voltmeter
Figure 3. Example of how to connect
the ammeter to measure the voltage.
2.1 Use of the Ohmmeter Without energize the elements, measure the resistance value of each resistors and complete the table 1.
Figure 4. How to connect the ohmmeter to measure the resistance value.
Resistive values measurement. Resistance Digital ohmmeter measurement Ω
Color code values Ω
R1
984.9
1K
R2
555.0
560
R3
665.1
680
R4
324.0
330
2.2 Use of the Voltmeter The figure 3 show how to measure the voltage of an element. With the power supply off, build the circuit of the Figure 5. Once assembled turn circuit voltage source and fill in Table 2.
Figure 5. Schematic diagram
Figure 6. How to measure the voltage in each resistance and in both resistance. Table 2. Voltage measuring. Voltage source E=1V E=2V E=3V E=4V E=5V E=6V E=7V E=8V E=9V E=10V E=11V E=12V
Voltage in R1 y R2 .997 1.996 2.996 3.996 4.996 5.996 6.995 7.995 8.989 10.021 11.015 12.023
Digital Multimeter Voltage in R1 .750 1.502 2.255 3.007 3.759 4.512 5.263 6.015 6.76 7.535 8.290 9.043
Voltage in R2 .246 .494 .742 .989 1.236 1.484 1.732 1.954 2.227 2.484 2.230 2.983
2.3 Use of the Ammeter The Figure 2 show how to connect the ammeter for the measure of the intensity of an element. With the power supply off, build the circuit of the figure 7. Once armed the circuit turn the voltage source and fill the table 3.
Figure 7. Schematic diagram
Figure 8. How to measure the intensity in each resistors and in both resistors. Table 3. Current measuring. Voltage source Current in R1 y R2 2.2 mA 2.54 mA 9.9 mA 13.2 mA 16.53 mA 19.53 mA 23.0 mA 26.0 mA 29.57 mA 32.8 mA 36.0 mA 39.4 mA
E=1V E=2V E=3V E=4V E=5V E=6V E=7V E=8V E=9V E=10V E=11V E=12V
Digital Multimeter Current in R1 1.49 mA 3.02 mA 5.2 mA 7.24 mA 9.16 mA 10.8 mA 12.77 mA 14.4 mA 16.3 mA 18.21 mA 19.95 mA 21.8 mA
Current in R2 2.8 mA 2.5 mA 4.5 mA 5.9 mA 7.41 mA 8.8 mA 10.4 mA 11.7 mA 13.3 mA 14.8 mA 16.2 mA 17.8 mA
3. Questions: 1. What is the characteristic of a series circuit? Two of more elements are connected in series if they share only one node, that means the elements have the same current. 2. What’s the characteristic of a parallel circuit? Two or more elements are connected in parallel when they share their two nodes, it means, they have the same tension.
3. What’s the main difference between an analog and a digital meter? The analog meter is a pointer that moves in relation to the magnitude of the variable measured; the digital meter has numbers in the display indicating the magnitude of the variable measuring. 4. Why shouldn’t an ammeter be connected in parallel? Because it won’t show anything, the ammeter may be damaged because their resistance is very small and the current will be higher. 5. Why do we have to de-energize the circuit when we are measuring the resistance in the electric circuit?
Because when it’s energized, there is a current, and this current could alter the measure.
4. Conclusions. -
The objectives of the practice, which were met, were be
able to: 1) Properly use the digital ohmmeter. 2) Properly use the digital voltmeter. 3) Using digital ammeter properly. This capabilities were developed during the practice, Section II.1 where the use of the ohmmeter is especified and with the obtained data fill Table 1, the ability to use voltmeter was developed in the section II.2 where we will measure with the voltmeter and the r esults fill table 2, and section II.3 helps us with the ability to use the ammeter which will give us more data to fill table 3. Once finished the practice I can conclude that the multimeter can help us to measure different types of values as are the voltage, the current and the resistance of the elements, also that the values of the elements are approximated that the real values but it doesn ’t affect in this practice.
The color code used in electronics to indicate the values of the electronic components. Each color band represents a number and the order of the color band will represent a number value. The first 2 color bands indicate a number. The 3rd color band indicates the value to multiplier the first two numbers or, in other words, the number of zeros to add. The fourth band indicates the tolerance of the resistor.
Is a board with holes that are electrically conn ected together internally, usually following line patterns, which can be inserted electronic components and wires for assembly and prototyping electronic circuits and similar systems. It is made of two materials, insulatio n, usually a plastic, and a conductor connecting together the various holes.
