Carbon resistors power - Electronic Circuits Projects Diagrams Free

sbayeta · 28th July 2003, 02:05 PM

Hi,
How do I tell the power of a carbon resistor from its size ? Is there any reference on the web I can consult ?

Thanks

Nostrafus · 28th July 2003, 03:09 PM

A Carbon film resistor can be identified by it's markings, there should be between 3-5 colored bands which are used to identify a resistor.

Also size doesn't always matter when it comes to electronics, although with carbon film resistors it does, the longer the piece of carbon film, the more resistance, though it usually doesn't take much.

Here's the link.

http://webhome.idirect.com/~jadams/e...esist_calc.htm

Note: Look VERY CAREFULLY at the resistor, some colors are difficult to distinguish like blue/green, and violet/blue, I know the last one sounds kind of funky, but one time it took me about 1/2 an hour to decide which one it was, I looked under many different lights, but didn't actually decide until I went out into sunlight (The best to identify colors under, other lights emit a slightly different color, like a yellowish/pale color which can impare your ability to identify some colors) and some of these bands can be under 1mm in size so a magnifying glass may help.

sbayeta · 28th July 2003, 03:13 PM

Quote:

Originally Posted by Nostrafus

A Carbon film resistor can be identified by it's markings, there should be between 3-5 colored bands which are used to identify a resistor.

Also size doesn't always matter when it comes to electronics, although with carbon film resistors it does, the longer the piece of carbon film, the more resistance, though it usually doesn't take much.

Here's the link.

http://webhome.idirect.com/~jadams/e...esist_calc.htm

Note: Look VERY CAREFULLY at the resistor, some colors are difficult to distinguish like blue/green, and violet/blue, I know the last one sounds kind of funky, but one time it took me about 1/2 an hour to decide which one it was, I looked under many different lights, but didn't actually decide until I went out into sunlight (The best to identify colors under, other lights emit a slightly different color, like a yellowish/pale color which can impare your ability to identify some colors) and some of these bands can be under 1mm in size so a magnifying glass may help.

Thanks for the info, but what I need to know is how to distinguish the power of a resistor, not its resistance.

Any ideas on this ?

bogdanfirst · 28th July 2003, 04:18 PM

take a look at this
or go here to select other categories.

subzero349 · 28th July 2003, 09:07 PM

Quote:

Originally Posted by Nostrafus

Note: Look VERY CAREFULLY at the resistor, some colors are difficult to distinguish like blue/green, and violet/blue, I know the last one sounds kind of funky, but one time it took me about 1/2 an hour to decide which one it was, I looked under many different lights, but didn't actually decide until I went out into sunlight (The best to identify colors under, other lights emit a slightly different color, like a yellowish/pale color which can impare your ability to identify some colors) and some of these bands can be under 1mm in size so a magnifying glass may help.

a handy trick to finding out the resistance of a resistor if the colours are bad is to measure them with a DMM...

Noggin · 29th July 2003, 11:42 AM

my lazy butt skips the bands and goes straight for the DMM. As for determining power, I dont know

daviddoria · 29th July 2003, 05:53 PM

haha i agree with skipping the bands... who is going to be playing with carbon resistors w/o a DMM nearby anyway?

bogdanfirst · 29th July 2003, 06:45 PM

i don't see any way to determine the power of the reistor exept from it's size.....
maybe the colour of the reistor means something.....?

sbayeta · 29th July 2003, 06:48 PM

Quote:

Originally Posted by bogdanfirst

i don't see any way to determine the power of the reistor exept from it's size.....
maybe the colour of the reistor means something.....?

I know that. What I need to know is if is there any reference to determine the power.
E.g.:
Lenght: 10mm, Diameter: 1mm ----> 1/4W
Lenght: 20mm, Diameter: 3mm ----> 1W
etc....

bogdanfirst · 29th July 2003, 07:21 PM

look at the links i posted......the first one.....it has a chart that contains the dimensions of different power resistors.
i think that the dimensions don't matter from different manufacturers

sbayeta · 29th July 2003, 07:24 PM

Quote:

Originally Posted by bogdanfirst

look at the links i posted......the first one.....it has a chart that contains the dimensions of different power resistors.
i think that the dimensions don't matter from different manufacturers

I saw that when you posted it, and was great. But my doubt remains if is there a standard reference

bogdanfirst · 29th July 2003, 08:22 PM

i don't know about standards....,but the fact is that you will not find a 2 W resistor from one manufacturer the same size as a 1/2W resistor from another manufacturer....if you know what i mean/////

Nostrafus · 29th July 2003, 08:39 PM

Quote:

a handy trick to finding out the resistance of a resistor if the colours are bad is to measure them with a DMM...

Yeah, but not everyone has a DMM, like me, I just haven't had much spare time to go get one, nor the spare cash, because if I get one, I'm probably gonna get one of the $100 that can measure voltage, resistance, capacitance, and all the extras, because I don't want to have to spend a whole lot of time trying to identify components.

subzero349 · 29th July 2003, 08:51 PM

Quote:

I'm probably gonna get one of the $100 that can measure voltage, resistance, capacitance, and all the extras, because I don't want to have to spend a whole lot of time trying to identify components.

Good idea, a DMM that can measure the values of caps (along with resistance, voltage, current, and all the other standard stuff) is very worth the money...

As for the power of carbon resistors I would bet there is no set standard. Obviously size plays a factor, so good luck sbeyeta!!

bogdanfirst · 30th July 2003, 03:27 PM

yes, it can do that, but you CAN NOT mesure the power of a resistor with a DMM
the best way is from it's size, and probably the only way

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28th July 2003, 02:05 PM	(permalink)
sbayeta	Carbon resistors power Hi, How do I tell the power of a carbon resistor from its size ? Is there any reference on the web I can consult ? Thanks

28th July 2003, 03:09 PM	(permalink)
Nostrafus	A Carbon film resistor can be identified by it's markings, there should be between 3-5 colored bands which are used to identify a resistor. Also size doesn't always matter when it comes to electronics, although with carbon film resistors it does, the longer the piece of carbon film, the more resistance, though it usually doesn't take much. Here's the link. http://webhome.idirect.com/~jadams/e...esist_calc.htm Note: Look VERY CAREFULLY at the resistor, some colors are difficult to distinguish like blue/green, and violet/blue, I know the last one sounds kind of funky, but one time it took me about 1/2 an hour to decide which one it was, I looked under many different lights, but didn't actually decide until I went out into sunlight (The best to identify colors under, other lights emit a slightly different color, like a yellowish/pale color which can impare your ability to identify some colors) and some of these bands can be under 1mm in size so a magnifying glass may help. __________________ E=MC^18357891237358179238, it\'ll still come out right every time. Try it some time, it\'s all relative to the equation. Take that Einstein.

28th July 2003, 04:18 PM	(permalink)
bogdanfirst	take a look at this or go here to select other categories.

29th July 2003, 11:42 AM	(permalink)
Noggin	my lazy butt skips the bands and goes straight for the DMM. As for determining power, I dont know __________________ A rectangular bear is just a polar bear after a coordinate transform. -- I dunno who. A recent study shows that research causes cancer in rats. -- I dunno who said that one either.

29th July 2003, 05:53 PM	(permalink)
daviddoria	haha i agree with skipping the bands... who is going to be playing with carbon resistors w/o a DMM nearby anyway? __________________ thanks, david

29th July 2003, 06:45 PM	(permalink)
bogdanfirst	i don't see any way to determine the power of the reistor exept from it's size..... maybe the colour of the reistor means something.....?

29th July 2003, 07:21 PM	(permalink)
bogdanfirst	look at the links i posted......the first one.....it has a chart that contains the dimensions of different power resistors. i think that the dimensions don't matter from different manufacturers

29th July 2003, 08:22 PM	(permalink)
bogdanfirst	i don't know about standards....,but the fact is that you will not find a 2 W resistor from one manufacturer the same size as a 1/2W resistor from another manufacturer....if you know what i mean/////

30th July 2003, 03:27 PM	(permalink)
bogdanfirst	yes, it can do that, but you CAN NOT mesure the power of a resistor with a DMM the best way is from it's size, and probably the only way