An ohmmeter is an electronic device that measures resistance in electronic circuit components. The ohmmeter consists of a scale display with an indicator needle or digital display, a range selector, and two leads (probes). Learn how to use this tool to learn how to measure the resistance of almost any object.
Step
Step 1. Completely disconnect and/or turn off all power to the circuit under test
In order to obtain accurate measurements and ensure your safety, it is recommended that the circuit under test must be completely off. Ohmmeter will provide voltage / voltage and current so it does not require power from other sources. As per Blue Point's volt/ohmmeter instruction statement, testing electrical circuits can "damage the meter, circuit, and *your* self."
Step 2. Choose an ohmmeter that suits your needs
Analog ohmmeters have very basic functionality and are inexpensive, as well as a general range from 0-10 to 0-10000 ohms. Digital ohmmeters have a similar or "auto-range" range, that is, they read the device's resistance and select the correct range automatically.
Step 3. Check the ohmmeter to see the condition of the battery
A newly purchased ohmmeter may already have a built-in battery, or it may come in a separate package for later pairing.
Step 4. Insert the test lead into the meter socket
For multifunction meters, you will see a “common”, or negative connection, and a “positive” connection. They may be distinguished by red (+) and black (-) colors.
Step 5. Set the meter to zero if the device is equipped with a rotary knob
Note that the measurement results are displayed in the opposite direction of most gauges in general, i.e. low resistance on the right, and high resistance on the left. Zero resistance should be monitored when the probes are directly connected to each other. You can adjust the resistance by touching the ends of the probes together and turning the "adjust" knob until the needle points to zero.
Step 6. Select the circuit or electronic device you want to test
As an exercise, you could try anything that conducts electricity, such as aluminum foil or pencil marks on a piece of paper. To understand the level of accuracy of the measurement results, buy several different resistors from an electronics store, or some other device whose resistance value is known.
Step 7. Touch one probe to one end of the electrical circuit, and the other probe to the other end, and record the measurement results on the device
If you purchased a 100 ohm resistor, place a probe across each conductor on the resistor, and select a 1000-10,000 ohm range. After that, check the meter to make sure the result is indeed 1000 ohms.
Step 8. Isolate the components in the electrical circuit connected by wires to test them one by one
If you read the ohms number on the resistor on the printed circuit board, it means that you will need to unsold or unscrew the resistor to make sure the results obtained from other paths in the circuit are correct.
Step 9. Read the resistance in the wires or prongs of the circuit to see if there is a short or open damage in the circuit
If the measurement results show "infinite ohms" (infinite ohms), it means that there is no path that can be passed by electric current. In other words, there may be a charred component in the circuit, or a faulty conductor. However, because many circuits have "gate" devices (transistors or semiconductors), diodes, and capacitors, you may not read the continuation even when the complete circuit is completely connected, which means it is difficult to test the complete circuit using just one ohmmeter.
Step 10. Turn off the ohmmeter when not in use
If not turned off, sometimes the probe lead can short while the device is stored and drain the battery.
Tips
- If you are buying an ohmmeter for normal use only, buy a good quality multimeter, which is capable of testing other electrical values such as voltage and current.
- Familiarize yourself with electrical and electronic terminology, electrical circuit board schematics, and schematic (or wiring) diagrams.
- You need to know that even if the resistor shows a 1000 ohm reading, the deviation can be up to 150 ohms. Small resistors will deviate by a few ohms, and this deviation is more in large resistors
- Try different experiments with electrical conductivity. Draw a line on a piece of paper with a graphite pencil, and touch a probe at each end. You will find that these pencil lines do conduct electricity.
- To learn about the ohmmeter's range, you can also buy a variety of resistors and test each for resistance.
