Re: What's my resistor?
- From: dplatt@xxxxxxxxxxxx (Dave Platt)
- Date: Wed, 21 Sep 2005 20:14:46 -0000
In article <dgsdgi$j2f$1@xxxxxxxxxxxxxxxxxxxxx>, Bill <a@xxxxx> wrote:
>I am an electronics newbie, so please be gentle with me! I am trying to
>make up a circuit as described on a web site. All it requires is a
>couple of connectors, a transistor, a resistor and a chip. It is the
>resistor I am having problems with. It is supposed to be a 100K
>resistor. I bought one at Maplin for the pricey sum of 9p. But I
>wanted to check that it was the correct one, so I used my meter on it.
>It has 5 bands: brown, black, black, black, brown. According to my
>meter, on the 200 scale, it says 100. On the 200K scale it says 0.1.
>surely this must not be the correct resistor (I would have expected to
>see 100 on the 200K scale not 0.1). I looked at the Maplin web site
>and found a picture of the resistor I bought and it says it is a 100K
>resistor - at this point I got confused.
>
>Can someone please help me. What 5 coloured bands should I see on a
>100K resistor.
See http://www.electronics-tutorials.com/basics/resistor-color-code.htm
for an explanation.
Briefly: for the digits, brown corresponds to a "1", black to a "0".
There are three digits indicating the value, one digit which indicates
the multiplier (a power-of-ten), and the final digit indicates the
precision.
What you have, it appears, is a 10001 coding, which means
(100 * 10^0), (1%) resistor. In other words, the color coding says
that it's a 100-ohm 1%-precision resistor, which matches up nicely to
what your meter is saying.
A 100K 1% resistor would be (100 * 10^3), (1%), which would be
color-coded brown-black-black-orange-brown.
A less-precise resistor such as a 5% would have only four bands, with
two digits for the value. A 100-ohm resistor of this sort would be
coded brown-black-brown-gold (10 * 10^1) (5%), and a 100k-ohm resistor
would be brown-black-yellow-gold (10 * 10^4) (5%).
In the European system of writing resistor values, it's usual to write
an "R" or "K" or "M" in the location of a decimal point or comma...
for instance, "2R2" would be 2.2 ohms, "2K2" would be 2,200 ohms,
"10M" would be 10,000,000 ohms, and so forth.
In this scheme of writing, what you *wanted* was a 100K, and what you
got was a 100R.
--
Dave Platt <dplatt@xxxxxxxxxxxx> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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