Struggling to understand a 5 band resistor

Thread Starter

diesalweasel

Joined Aug 28, 2010
36
Hi need some help here i have a resistor on me the colour as followed Orange Orange black and silver and brown at very end
So it my under standing is 330x0.01 = 3.3
Is this a 3,300 kohm resister . The silver band has threw me off as I'm not that good with maths

It a blue 1/4 watt resister

One thing does not make sence. I have a dm if i set it on to 200ohm the resistor shows up as 0.35
If i set the meter to 2k it shows up as .003
If i set the meter to 20k it shows 0.00

My meter is uni-t ut50c

Thanks in advance regards james

RichardO

Joined May 4, 2013
2,271
I am guessing that it is 0.33 ohms, 1%.

My reasoning is that 330 is 33 with no zeros following (not 330). The silver is 0.01 multiplier. Brown is 1% tolerance.

Remember that your meter probes have resistance and the connection to the resistor also has some resistance. This makes measuring small resistance values tricky. One way to reduce the error is to make a measurement with the probes shorted together and subtract that from the resistor reading.

AlbertHall

Joined Jun 4, 2014
11,952

dl324

Joined Mar 30, 2015
14,303
Orange Orange black and silver and brown at very end
So it my under standing is 330x0.01 = 3.3
This is correct.
One thing does not make sence. I have a dm if i set it on to 200ohm the resistor shows up as 0.35
If i set the meter to 2k it shows up as .003

My meter is uni-t ut50c
Sounds like something wrong with the 200 ohm range. What resistance does it show for just the leads?

dl324

Joined Mar 30, 2015
14,303
One way to reduce the error is to make a measurement with the probes shorted together and subtract that from the resistor reading.
That would only make sense if the reading was high. His is reading low.

AlbertHall

Joined Jun 4, 2014
11,952
That would only make sense if the reading was high. His is reading low.
Or it's a typo with one too many zeroes.

gerty

Joined Aug 30, 2007
1,302
It also makes a difference if you are measuring the resistor is in a circuit or not, not always, but usually.

KL7AJ

Joined Nov 4, 2008
2,229
Hi need some help here i have a resistor on me the colour as followed Orange Orange black and silver and brown at very end
So it my under standing is 330x0.01 = 3.3
Is this a 3,300 kohm resister . The silver band has threw me off as I'm not that good with maths

It a blue 1/4 watt resister

One thing does not make sence. I have a dm if i set it on to 200ohm the resistor shows up as 0.35
If i set the meter to 2k it shows up as .003
If i set the meter to 20k it shows 0.00

My meter is uni-t ut50c

Thanks in advance regards james
Join the club~

Metal film resistors have THREE significant figures, not just two, and one multiplier. The remaining band is tolerance. Some resistors have a sixth band, which is either a temperature coefficient or a failure rate (reliability) figure.

RichardO

Joined May 4, 2013
2,271
That would only make sense if the reading was high. His is reading low.
Not if the resistance is 0.33 ohms as I believe it is.

WBahn

Joined Mar 31, 2012
26,398
I am guessing that it is 0.33 ohms, 1%.

My reasoning is that 330 is 33 with no zeros following (not 330). The silver is 0.01 multiplier. Brown is 1% tolerance.

Remember that your meter probes have resistance and the connection to the resistor also has some resistance. This makes measuring small resistance values tricky. One way to reduce the error is to make a measurement with the probes shorted together and subtract that from the resistor reading.

View attachment 136056
But the three color bands for the values should translate to three digits. Orange-orange-black should translate to 330 and then the silver should be a multiplier of 0.01 ohm, yielding 3.3 ohms.

I can't rule out a trailing black value band being intended to be ignored completely, but I don't think this would be standard -- and it's not indicated by the chart you included. I would expect a 0.33 ohm resistor to be marked as

black-orange-orange-silver-brown

But this assumes that a leading value band can be black. I don't know that this is allowed.

RichardO

Joined May 4, 2013
2,271
But the three color bands for the values should translate to three digits. Orange-orange-black should translate to 330 and then the silver should be a multiplier of 0.01 ohm, yielding 3.3 ohms.

I can't rule out a trailing black value band being intended to be ignored completely, but I don't think this would be standard -- and it's not indicated by the chart you included. I would expect a 0.33 ohm resistor to be marked as

black-orange-orange-silver-brown
You and others are right. I gave got it wrong trying to use both the zero and silver as multipliers.

Now I have no idea what the value actually should be.

WBahn

Joined Mar 31, 2012
26,398
You and others are right. I gave got it wrong trying to use both the zero and silver as multipliers.

Now I have no idea what the value actually should be.
I've been trying to find a site that might talk about exceptions for low-valued resistors. I found a site that claims that a five-band resistor having a fourth band of silver or gold is actually a four-band resistor with a tempco band. That would make this a 33 ohm, 10% resistor with a 100 ppm/K tempco. But that value isn't at all consistent with the given measurements.

ebeowulf17

Joined Aug 12, 2014
3,275
FWIW, I've got a meter that has just one band off by a factor of ten from what it indicates it should be. It's quite consistent and accurate, once you know there's a factor of ten error. I don't remember which meter or which band at this point, but it wouldn't surprise me if our meters have a chip and/or program in common and the 200ohm range is off by a factor of ten.

My guess is 3.3 ohm.