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