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### Calculating resistor values in parallel and in series

Posted: 22 Feb 2008, 13:54
I bought a big selection pack of resistors, and I have 50 different values of resistors to play with. Some are commonly used in effects, but quite a lot of them are more obscure values that don't seem to be of much use to me.

Is it possible to combine 2 more obscure values to achive 1 value I need?

For an example, would wiring 2 x 330R resistors in parrallel = the same as 1 x 660R resistor on it's own?

And if so, can you mix different values like a 1k and a 2.2k to achive 3.2k?

All these values are pulled out of thin air and not relevant to the question, they're just examples for the sake of my understanding.

I'd really appreciate someone's help on this if anyone knows the answer. Thanks.

Posted: 22 Feb 2008, 15:09
You can put them in series to add up to the value you need. In parallel, the value you get is inversely proportional to the sum of the inverses of the individual values of the two resistors.

ex. R1= 8k, R2=5k.
(R1||R2)^-1 = 1/8 + 1/5
= 5/40 + 8/40
= 13/40

so, R1||R2 = 40/13 ~ 3.07k

parallel calculator
http://www.calculator.net/resistor-calculator.html