Calculating resistor values in parallel and in series

Frequently asked question regarding resistors, potentiometers, types, requirements, ratings etc.

Calculating resistor values in parallel and in series

Postby ChuckNorris1982 » 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.
Last edited by modman on 17 Mar 2016, 02:51, edited 2 times in total.
Reason: Edited topic title
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Postby madbean » 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
http://www.learningaboutelectronics.com ... ulator.php
http://physics.bu.edu/py106/notes/Circuits.html
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Postby ChuckNorris1982 » 22 Feb 2008, 15:29

Thanks mate, that's most helpful indeed.
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fl301 substitute

Postby ballfire » 17 Mar 2016, 01:28

hello everybody..

i have a question what would i substitute in 24k, 510k, 51k, and 5.1k resistors on fl301 flanger clone on the schematic parts?? becasue we dont have any of these resistor in our place..

thanks ..
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