mrtinb wrote:- I have received a package with 10K ohm resistors that I've ordered. The label says 10K, but the colors are Brown, Red, Black, Black, Brown. I'm not very experienced with electronics, but my book says that that is 1.2 ohm. When I use my multimeter set at "200k", then the display says "10.0". Can anyone tell me if this is the correct resistor, that has been shipped to me?
Hi
There are on-line resistor colour code calculators like
this one that help. Note that any calculator cannot handle all the variations used by resistor manufacturers over the years. So it may not get it right every time.
Now, resistor colour codes come in a number of variations. The clue is the number of bands and the colours of the last two. Of course, the tricky bit is, which two are the last two....
With your "10kΩ" resistor, the code can be either:
Brown, Red, Black, Black, Brown
or
Brown, Black, Black, Red, Brown
So we decode both:
Brown = 1, Red = 2, Black = 0, Black = X 1, Brown = 1%
= 120 X 1 = 120Ω
but reading the other way gives
Brown =1, Black = 0, Black = 0, Red = X 100, Brown = 1%
= 100 times 100 = 10000Ω = 10kΩ
Note: this is for resistors with a four band colour code to make the number / value. There also exist resistors with a three band band colour code to make the number / value, these have the tolerance (brown = 1%) followed by a red band indicating the temperature coefficient += 50ppm/°C.
mrtinb wrote:- I have 2.2K, 2.7K, 200, 10K resistors. I need 5.1K ohm resistors that I forgot to order. Can any of the resistors I have be combined to this value?
If you connect resistors in series ( one lead connected directly to the lead of the next resistor), the combined value is the sum of all the resistors in the series chain. So you have a choice of 2.2kΩ + 2.7kΩ = 4.9kΩ, or 2.7kΩ + 2.7kΩ = 5.4kΩ
If you connect
two resistors of the same value in parallel, (leads connected together at each end), the resulting resistance is half the value of the resistors.
So two 10kΩ resistors connected in parallel gives 5kΩ.
In practice, most circuits are fine with a slightly different resistor value, so either 4.9kΩ, or 5kΩ should be okay.
I hope that helps
Mark