Author Topic: Sliding varable pots 'Elp  (Read 1344 times)

Offline frenulem - No.5417

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Sliding varable pots 'Elp
« on: November 06, 2009, 06:32:46 AM »
i want an 47K pot(sliding) for school But can only get hold of a 10k 0r 100k is there any way of maybe putting in a resistor on the start of the por to make the min up ? (guppy question?)

Offline FOOKz™

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Re: Sliding varable pots 'Elp
« Reply #1 on: November 22, 2009, 05:30:34 PM »
you can put resistors in series with your pot to increase the resistance, obviously. but if you want to decrease the resistance you have to put a resistor in parallel. To calculate the resistance for a paralell setup you must use the product over sum formula:

(R1-1 + R2-1 + R3-1 ... )-1


sooo if you want to make a potentiometer that at approx 47K ohms out of a 100K pot then you estimate that 47 is about half of 100, so think whats about half of 47...

24 is about half of 47, add 24k to 47k to find the estimated value needed.

24k + 47k = 71k
we are estimating we need a 71K ohm resistor to paralell with the 100k pot. Now lets plug our numbers into the formula:

( 100,000-1 + 71,000-1 )-1 = 41,520 Ohms.

Thats Pretty Damn Close to your needed 47K Ohm Value. Play Around with the numbers and see what you can get.

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Offline frenulem - No.5417

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Re: Sliding varable pots 'Elp
« Reply #2 on: January 11, 2010, 03:04:13 PM »
Major Bump

Yeah Helped allot thanks I need this 'cuz it bumped my C Grade to a A Thanks

 

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