Measuring resistance on electronic components whether doing it individually or in-circuit, is not simple unless you had learned how to read resistance scale using an ohmmeter of an analog multi-tester. It’s not as hard as you think maybe by looking the overwhelming numbers and values. Once you understand it, you will realize how simple it is.
As you can see in the image below, resistance scale is located in the top most part of a meter panel. You may have noticed a descending order of number. From left (∞) to right (0). In practice, reading values always starts from zero. Therefore we will read resistance values from right to left which is zero (0) to infinity (∞) .
Note: Reading resistance values is an exact opposite of reading “voltage” and “current” since ACV (Ac voltmeter) and DCV (Dc voltmeter) scale is in ascending order. You may have noticed how their values starts from left (0, 0, 0) to right (10, 50, 250).
Since we will read resistance values from right to left, see to it that the gaps between numbers are not equally divided. Please don’t get so confused why it is not equal. In fact, it’s not a big deal. After all what we need to learn is the value of each scale between each numbers. Those small vertical lines that divide on each number is a scale. Each scale has a value with respect to each nearest number.
- To fully understand it, we will make a list of numbers from zero (0) to infinity (∞) with its individual scale and value.
- See the red lines below the resistance scale and compare it to the list below.
0-1 – is divided by 5 scales. Each scale has a value of 0.2 ohm. Therefore 0.2 ohm multiplied by 5 scales is equal to 1 ohm.
1-2 – also divided by 5 scales. Each scale has a value of 0.2 ohm. Therefore 0.2 ohm multiplied by 5 scales is equal to 1 ohm. Adding all the value from zero, we get a total of 2 ohms.
2-5 – is divided by 6 scales. Each scale has a value of 0.5 ohm. Therefore 0.5 ohm multiplied by 6 scales is equal to 3 ohms. Adding all the value from zero, we get a total of 5 ohms.
5-10 – is divided by 10 scales. Each scale has a value of 0.5 ohm. Therefore 0.5 ohm multiplied by 10 scales is equal to 5 ohms. Adding all the value from zero, we get a total of 10 ohms.
10-20 – is divided by 10 scales. Each scale has a value of 1 ohm. Therefore 1 ohm multiplied by 10 scales is equal to 10 ohms. Adding all the value from zero, we get a total of 20 ohms.
20-30 – is divided by 5 scales. Each scale has a value of 2 ohms. Therefore 2 ohms multiplied by 5 scales is equal to 10 ohms.
Adding all the value from zero, we get a total of 30 ohms.
30-50 – is divided by 10 scales. Each scale has a value of 2 ohms. Therefore 2 ohms multiplied by 10 scales is equal to 20 ohms. Adding all the value from zero, we get a total of 50 ohms.
50-100 – is divided by 10 scales. Each scale has a value of 5 ohms. Therefore 5 ohms multiplied by 10 scales is equal to 50 ohms. Adding all the value from zero, we get a total of 100 ohms.
100-200 – is divided by 5 scales. Each scale has a value of 20 ohms. Therefore 20 ohms multiplied by 5 scales is equal to 100 ohms. Adding all the value from zero, we get a total of 200 ohms.
200-500 – is divided by 4 scales. Each scale has a value of 75 ohms. Therefore 75 ohms multiplied by 4 scales is equal to 300 ohms. Adding all the value from zero, we get a total of 500 ohms.
500-1k – is not divided by a scale. Therefore from 500, you will get the value of 1 kilo-ohms (1K) by adding 500 ohms. So, it is very obvious that the gap between 500 ohms and 1k is 500 ohms. Adding all the value from zero, we get a total of 1 kilo-ohms (1K).
1k-2k – is not divided by a scale. Therefore from 1K, you will get the value of 2k by adding 1K. So, the gap is obviously 1 kilo-ohms (1K). Adding all the value from zero, we get a total of 2 kilo-ohms (2K).
Note: K stands for Kilo which means Thousand.
Any value that goes beyond 2K or 2 kilo-ohms value has a very high resistance and exceed the x1 multiplier range of an ohmmeter.
Please note that the highest resistance scale is only limited to 2k or 2 kilo-ohm resistance. If you need to measure resistance which is higher than 2 kilo-ohms, set the ohmmeter range to a higher multiplier range and so on.
Learning to read resistance values is easy. Just by knowing the value of each scale individually could fulfill it. But there’s more to learn if you dig deeper.
Here are the questions that arises on your thoughts:
What is a multiplier?
These are the 4 range of an ohmmeter, as you can see in the image below. An ohmmeter is divided by four main settings.
a) x1 – select this range so that any value in the resistance scale is multiplied by 1.
b) x10 – select this range so that any value in the resistance scale is multiplied by 10.
c) x100 – select this range so that any value in the resistance scale is multiplied by 100.
d) x1k – select this range so that any value in the resistance scale is multiplied by 1k or 1 thousand.
Does each range is has its own sensitivity?
- x1 – has the lowest sensitivity
- x1k – has the highest sensitivity
What range should be used in resistance measurement?
- x1 – Select this range if you are measuring resistance below 2 kilo-ohms.
- x10 – Select this range if you are measuring resistance below 20 kilo-ohms.
- x100 – Select this range if you are measuring resistance below 200 kilo-ohms.
- x1k – Select this range if you are measuring resistance below 2 mega-ohms.
Learning resistance measurement is simple but you need to practice. Familiarize the value of each scale and memorize it. Put it in practice, measure the resistance of an actual electronic components such as resistors, transistors and diodes. It’s not very long you realize you’d already done it with ease.
If i missed something or messes something up, please put it in the comments below and i’ll gladly make an update right away.
Fix it Phillip 