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Carbon Film Resistors

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  • Member since
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  • From: Pottstown PA
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Posted by rdgk1se3019 on Sunday, January 13, 2013 9:52 PM

Blind Bruce

All of these replies pertain to carbon resistors. Carbon FILM resistors don't usually have color code bands but have their value printed on them. Film resistors are different from carbons in their temperature coefficents. Films are more stable with temperature variations.

Uh.....yeah ......the resistors that I do have .........have the 4 colors on them AND they are axial.

Dennis Blank Jr.

CEO,COO,CFO,CMO,Bossman,Slavedriver,Engineer,Trackforeman,Grunt. Birdsboro & Reading Railroad

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Posted by BroadwayLion on Sunday, January 13, 2013 12:02 PM

If you need an EXACT value from a resistor, you can measure that value for yourself before you use it.

LION is never that fussy about resistors. Him buys the cheapest available (1/4 W) and these happen to be in the 5% range. In lots of 1000 they are a penny each. I could use an 1/8th W resistor, but why pay more for it.

It is like buying Hydrogen Peroxide at the drug store: A pint costs 88c, and a half pint costs 98c. Go figure!

The Route of the Broadway Lion The Largest Subway Layout in North Dakota.

Here there be cats.                                LIONS with CAMERAS

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Posted by rrinker on Sunday, January 13, 2013 11:43 AM

 You're confusing leaded resistors with surface mount. Carbon film resistors come in standard axial lead packages with the color bands, just like carbon comp.

 The ones that have the value printed on instead of using color bands are the larger sandbar type high wattage resistors, and the tiny surface mount ones. Sandbar resistors usually list the value and tolerance printed as numbers - it will actually say 10% if it's 10% tolerance. Surface mount - well, if it has a 3 digit code for value it's almost always a 5% tolerance, if it has a 4 digit number or 3 digits plus a letter, it's a 1% or better.

              --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by Blind Bruce on Sunday, January 13, 2013 11:01 AM

All of these replies pertain to carbon resistors. Carbon FILM resistors don't usually have color code bands but have their value printed on them. Film resistors are different from carbons in their temperature coefficents. Films are more stable with temperature variations.

73

Bruce in the Peg

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Posted by rrinker on Saturday, January 12, 2013 2:52 PM

 It all depends on the use of the resistor if you need better than the common 10% tolerance. For example, the most common MR use is current limiting for LEDs lights. The recommended value of 1K gives about 9ma to the LED at typical track voltages. The LED will in fact work from around 2ma all the way up to about 20ma - so 9ma puts us well within the 'safe' zone (too low a current, it just won't light up, no ahrm done - too much current though, and it makes a neat little one time scale firecracker). 10% to either side of that is no big deal. Even 20% isn't. Waste of money to use a 5%, 1% or even finer resistor for this purpose.

 Now if you are building a radio and need to control frequency very tightly, 1% or better might be needed to make sure your circuit operates with the expected parameters.

 Bottom line, for MR use, common 10% resistors are just fine. If you get 5% or 1% given to you, they will work fine, but definitely do not spend extra to get the more precise versions.

                      --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by richg1998 on Saturday, January 12, 2013 2:50 PM

rdgk1se3019

So would you say that a 5% resistor is better to use than a 10% or 20% resistor?

If the circuit requires 5 percent, then yes.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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Posted by rdgk1se3019 on Saturday, January 12, 2013 2:09 PM

BroadwayLion

rdgk1se3019

Hi All,

I recently bought a pack of 1/8 watt carbon-film resistors and I noticed that the package says something about tolerance......gold 5%.....silver 10%......none 20%

What exactly is the tolerance for?

The manufacture of a resistor is sort of a random event. Like baking cookies: they do not all come out the same. So If I bake a batch of 100Ω resistors some will be exactly 100Ω, others might be between 95 and 105Ω and these get the 5% band and are sold at a higher price than those that fall between 90Ω and 110Ω which are painted for 10%. Those outside of these limits get no stripe and are sold off for even less.

Of course the ones I buy are all in the 5% range as manufacturing has become much more precise over the ages.These are no longer your grandfather's resistors.

ROAR

Okay.....now I get it.

Thanks to all that replied.

Dennis Blank Jr.

CEO,COO,CFO,CMO,Bossman,Slavedriver,Engineer,Trackforeman,Grunt. Birdsboro & Reading Railroad

  • Member since
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  • From: North Dakota
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Posted by BroadwayLion on Saturday, January 12, 2013 2:07 PM

rdgk1se3019

Hi All,

I recently bought a pack of 1/8 watt carbon-film resistors and I noticed that the package says something about tolerance......gold 5%.....silver 10%......none 20%

What exactly is the tolerance for?

The manufacture of a resistor is sort of a random event. Like baking cookies: they do not all come out the same. So If I bake a batch of 100Ω resistors some will be exactly 100Ω, others might be between 95 and 105Ω and these get the 5% band and are sold at a higher price than those that fall between 90Ω and 110Ω which are painted for 10%. Those outside of these limits get no stripe and are sold off for even less.

Of course the ones I buy are all in the 5% range as manufacturing has become much more precise over the ages.These are no longer your grandfather's resistors.

ROAR

The Route of the Broadway Lion The Largest Subway Layout in North Dakota.

Here there be cats.                                LIONS with CAMERAS

  • Member since
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Posted by rdgk1se3019 on Saturday, January 12, 2013 2:04 PM

So would you say that a 5% resistor is better to use than a 10% or 20% resistor?

Dennis Blank Jr.

CEO,COO,CFO,CMO,Bossman,Slavedriver,Engineer,Trackforeman,Grunt. Birdsboro & Reading Railroad

  • Member since
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  • From: Charlotte, NC
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Posted by Phoebe Vet on Saturday, January 12, 2013 1:51 PM

Most resistors use that code.  It is the last color band on the resistor.  As stated, it states that the value of the resistor is plus or minus that amount.

Dave

Lackawanna Route of the Phoebe Snow

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Posted by richg1998 on Saturday, January 12, 2013 1:40 PM

The resistance of each one. Plus or minus 5 percent as an example.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
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  • From: Pottstown PA
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Carbon Film Resistors
Posted by rdgk1se3019 on Saturday, January 12, 2013 1:26 PM

Hi All,

I recently bought a pack of 1/8 watt carbon-film resistors and I noticed that the package says something about tolerance......gold 5%.....silver 10%......none 20%

What exactly is the tolerance for?

Dennis Blank Jr.

CEO,COO,CFO,CMO,Bossman,Slavedriver,Engineer,Trackforeman,Grunt. Birdsboro & Reading Railroad

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