problem:cant tell apart resistors!
Jun 1, 2002 at 3:22 AM Thread Starter Post #1 of 14

HD-5000

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Hi guys, I have a serious problem that im pretty sure some of you can solve. You see, I bought the 50 piece Resistor Assortment from Radio Shack (that includes all of the values required for building a cmoy) ,but I look at the back of the box and I simply cannot tell one set of resistors from the next. Has anyone bought the same package and give me a few tips. Thanks!
 
Jun 1, 2002 at 4:32 AM Post #2 of 14

JMT

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I would advise that you invest in a digital multimeter. I don't even try to see the value markings (it's a bitch getting old), let alone read them.
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Jun 1, 2002 at 6:01 AM Post #3 of 14

kerelybonto

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They're not that small. Is your problem in seeing the lines or in interpreting them? Find a magnifying glass for the former, otherwise look for a reference that explains them better than the box. On tanget's advice I picked up Forrest Mim's Electronic Formulas, Symbols, and Circuits at RadioShack, which has a nice explanation of resistor code things and a bunch of other useful information.

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Jun 1, 2002 at 6:22 AM Post #4 of 14

JMT

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Quote:

They're not that small.


As you get older, they get smaller.
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I would still recommend a multimeter.
 
Jun 1, 2002 at 3:41 PM Post #6 of 14

HD-5000

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This is what it says no the back of the box:

Resistor Color Code
First to Third Fourth Color Band: Fifth Color Band:
Color Band: Tolerance
Black 0 Black x1 Brown 1%
Brown 2 Brown x10 Red 2%
Red 2 Red x100 Gold 5%
Orange 3 Orange x1k Silver 10%
Yellow 4 Yellow x10k None 20%
Green 5 Green x100k
Blue 6 Blue x1Meg
Violet 7 Silver divide by 100
Gray 8 Gold divide by 10
White 9



I repeat-I DON'T KNOW WHAT ANY OF THIS MEANS!!!
 
Jun 1, 2002 at 5:51 PM Post #7 of 14

JMT

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HD-5000

A digital multimeter is a small compact meter that will allow you to measure resistance, continuity, VAC and VDC (voltage), and sometimes, capacitance.

For color codes, this can explain it better than I can:

Resistor Color Codes
 
Jun 1, 2002 at 7:45 PM Post #8 of 14

kerelybonto

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That explanation's a little confusing, JMT. ... Try this, HD-5000:

There are four stripes. The first two are the ones that actually give you the two-digit numerical value. Their color will correspond to a number using the following code:

black = 0
brown = 1
red = 2
orange = 3
yellow = 4
green = 5
blue =
violet = 7
gray = 8
white = 9

So say you had a resitor with the first two stripes yellow and violet, respectively. That stands for 47.

The third digit is the multiplier. It uses the following code:

black = x1
brown = x10
red = x100
orange = x1000
yellow = x10,000
green = x100,000
blue = x1,000,00
violet = x10,000,000
gray = x100,000,000

So if your first two stripes are yellow and violet, meaning 47, and your third is orange, you multiply 47 x 1000 = 47 kohms.

The fourth stripe is tolerance. It uses the code:

brown = +-1%
gold = +-5%
silver = +-10%
no color = +-20%

So if your entire resistor has stripes of yellow, violet, orange, and brown, in that order, it's a 47 kohm resistor with a tolerance of +-1%.

kerelybonto
 
Jun 1, 2002 at 9:46 PM Post #10 of 14

erix

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You should consider getting yourself a little digital multimeter.

Not so much as to identify resistors but to find pairs of resistors that are close to each other in value. Those resistors are 5% tolerance - meaning a 100K resistor can actually measure between 95K-105K. On the Cmoy amp 5% is close enough to make the circuit perform correctly but you should really try to match the parts used on the left and right channels.

The small folding one that they sell at the shack is more than adequate.

ok,
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Jun 2, 2002 at 2:46 PM Post #12 of 14

jarthel

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A VOM (volt-ohm meter) is a must for DIYers. You may have assembled it but it doesn't mean it'll work right out. You'll be able to trace most problems using a VOM.

jayel
 
Jun 3, 2002 at 2:03 AM Post #14 of 14

tangent

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Just a few details to be cleaned up in this thread:

1. The 50-resistor Radio Shack assortment HD-5000 talked about consists of 1% tolerance metal film resistors.

2. As puppyslugg said, there is a fifth stripe on 1% resistors. The first three stripes are the value code, the fourth is the multiplier, and the fifth is the tolerance band (brown, for 1%). This is simply a result of higher precision: you need more digits to describe that precision.

3. Because of the different numbers of significant digits, you can't compare stripe codes of 5% and 1% resistors. A 100K 5% resistor would be brn-blk-yel-gold, but the corresponding 1% would be brn-blk-blk-org-brn.

I second (third? fourth?) the recommendation to get a meter of some kind. Even if it's an ancient analog one you find used somewhere, get a meter. It's good for more than just sorting resistors. Even if this is the last amplifier you ever build, you can use it to test batteries.
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Personally I only use stripe codes when examining resistors already in a circuit, since you often can't measure resistors accurately when they're in a circuit.

Using metal film's stripe codes is especially annoying, since the tolerance band (brown) is easily confused with a '1', so you end up spending a lot of time figuring out which end is which. With 5% resistors (usually carbon), it's less of an issue because if you see a gold band at one end, you know it's the tolerance band for a 5% resistor, because it couldn't be anything else.

I tried to learn the stripe code a few times, but I found the best way to learn the code is to just play with the resistors long enough. Eventually it just soaks in. Until you reach that point, using a meter's a lot easier, and it's more accurate besides.
 

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