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1. How to properly read resistor? 2. How does resistor power (ohms) affect the circuit? Answered

First question:
How do you read resistor color bands? I'm messing around with 5 band resistors in my circuit, and I realized I didn't have any 330 ohm resistors... I was surprised because the kit said they were 330 ohms. Little did I know that a lot of resistors have a different value if read backwards, for example, red, red, black, brown, brown could be 2.2k Ohms or 11k Ohms, depending on which way you read it. How do you know their orientation? Second question: How do resistors affect the circuit? Vague question, I know, but I'm utterly confused right now. My blue LED is supposed to have a current of 20mA, which with a 9V battery demands a 275 Ohm resistor... But the circuit works with a 10K Ohm resistor or a 100 Ohm resistor... I thought smaller resistors were less restricting and larger resistors were more restricting. But if the higher Ohm resistor is more restricting, should a wildy high Ohm resistor prevent the circuit from working? Because the LED doesn't fade in luminosity until I get to a 100K Ohm resistor, which makes me question what a resistor does if the circuit works with a 100 Ohm resistor or a 100K Ohm resistor?

Discussions

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DinasBhai

13 days ago

How do you read resistor color bands? I'm messing around with 5 band resistors in my circuit, and I realized I didn't have any 330 ohm resistors... I was surprised because the kit said they were 330 ohms. Little did I know that a lot of resistors have a different value if read backwards, for example, red, red, black, brown, brown could be 2.2k Ohms or 11k Ohms, depending on which way you read it. How do you know mobdro their orientation? Second question: How do resistors affect the circuit? Vague question, I know, but I'm utterly confused right now. My blue LED is supposed to have a current of 20mA, which with a 9V battery demands a 275 Ohm resistor... https://sarkariresult.onl/ But the circuit works with a 10K Ohm resistor or a 100 Ohm resistor... I thought smaller resistors were less restricting and larger resistors were more restricting. But if the higher Ohm resistor is more restricting, should a wildy high Ohm resistor prevent the circuit from working? Because the LED doesn't fade in luminosity until I get to a 100K Ohm resistor, which makes me question what a resistor does if the circuit works with a 100 Ohm resistor or a 100K Ohm resistor?

my issue got solved!!

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Downunder35m

16 days ago

5 band resistors should come labeled to avoid the confusion for the user.
In most cases there will be a slightly smaller gap between two bands - that should be the right side of the resistor.
Sadly even resistors from proper manufacturers often fail to provide enough visual difference here.
A clue can be the tolerance value - if you know it.
Check the chart here.
Most common tolerances are 1, 2, 5, 10% - as indicated by the colors brown, red, gold, silver.
Since you struggle I guess you have either 1 or 2% resistors.
330 OHM should read from left to right:
Orange, Orange, Black then the multiplier (again black), then tolerance (according to the chart and what you should have in the kit).

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randofo

16 days ago

5 band resistors are a pain in the neck to figure out the proper orientation for reading it. I recommend using a multimeter to measure their resistance or to buy 4-band resistors which are much more clear to read.

It is assuredly affecting the brightness of the LED, but you likely cannot see the difference until the value is increased significantly.

Check out the resistor lesson in my electronics class:
https://www.instructables.com/class/Electronics-Class/