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valvehead
Joined: 27 May 2009
Posts: 4
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 Posted: Wed May 27, 2009 10:11 pm Post subject: weird Resistor ? |
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Ive got a couple resistors on a board that are coming up weird as far as the color code...
They are , red / red / silver / gold / orange
or the other way around..
so what is the value ? |
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jts1957
Joined: 24 Nov 2008
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Location: Far, Far Away
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valvehead
Joined: 27 May 2009
Posts: 4
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| Posted: Thu May 28, 2009 1:24 am Post subject: |
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thanks.
i still dont get it though. silver isnt even listed |
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jts1957
Joined: 24 Nov 2008
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| Posted: Thu May 28, 2009 1:27 am Post subject: |
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Read through more carefully ...
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| If the 'multiplier exponent' band is Silver move the decimal point two places to the left. |
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valvehead
Joined: 27 May 2009
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| Posted: Thu May 28, 2009 1:29 am Post subject: |
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ahh-- didnt see that.
cheers ! |
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jts1957
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valvehead
Joined: 27 May 2009
Posts: 4
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| Posted: Thu May 28, 2009 3:56 am Post subject: |
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| i tried that, you cant enter silver on the 5 band . |
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jts1957
Joined: 24 Nov 2008
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| Posted: Thu May 28, 2009 6:04 am Post subject: |
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Try it on 4 band and, AGAIN 
Read (1st site) through more carefully ...
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If the resistor has one more band past the tolerance band it is a quality band.
Read the number as the '% Failure rate per 1000 hour' This is rated assuming full wattage being applied to the resistors. (To get better failure rates, resistors are typically specified to have twice the needed wattage dissipation that the circuit produces). Some resistors use this band for temco information. 1% resistors have three bands to read digits to the left of the multiplier. They have a different temperature coefficient in order to provide the 1% tolerance.
At 1% the temperature coefficient starts to become an important factor. at +/-200 ppm a change in temperature of 25 Deg C causes a value change of up to 1%. |
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vtech
Joined: 08 May 2006
Posts: 1264
Location: USA
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| Posted: Thu May 28, 2009 7:09 am Post subject: |
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Basically boils down to your circuit application but can be confusing looking through various calculator sites. Unless you are dealing with Military or precision equipment, the 4 band scheme can safely be used (in this case .22ohms@5 percent). However it can also be a 22.8ohm@3 percent in tight tolerance applications such as very low noise op-amps or an instrumentation circuit.
http://www.audionotekits.com/resistorcodes.html
http://www.hobby-hour.com/electronics/resistorcalculator.php
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kenray
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| Posted: Thu May 28, 2009 4:40 pm Post subject: |
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| what color is the resistor itself. sometimes that will tell you if it is a precision resistor or regular tolerance resistor. |
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