Changing Pot values

[tuffteef]

so changing pot values is do able right?

if i lay a 100k resistor across lugs 1 and 3 of a pot(100k) it should divide to 50 right?
or am i thinking about this wrong its been so long since i read a electronics book

[Scruffie]

Yup... along with a slight alteration in taper.

[tuffteef]

excellence i saved myself 11 dollars

[McSpunckle]

Yup... along with a slight alteration in taper.

Or huge, depending on the values.

It's a good way of testing if you need a different value, though!

[hclapp219]

Yup, and once that mod is complete the pedal you're working on becomes a Thaddeus Hogarth signature pedal.

[tuffteef]

Yup... along with a slight alteration in taper.

Or huge, depending on the values.

It's a good way of testing if you need a different value, though!

explain

i need scenarios

[eatyourguitar]

parallel resistor calculator
just leave one field blank and hit calculate.

I replaced a 220k resistor in the fuzz factory with a 250k pot. I wanted it to go from 0 ohms to 220k. so I just popped in R1 = 250k, Rtotal = 220k and the calculator tells me R2 = 1.8333333333333333Meg or 1M8. since 1.83 doesn't exist. i ordered a 1.87 metal film resistor. we plug that back in. R1 = 250K, R2 = 1.87M so we get Rtotal = 220.5188679245283K thats %0.025 tolerance. the pots are %5 tolerance so I say close enough.

you can also put the resistor across lug 1 and 2 since 2 and 3 would be tied together anyway. the opposite is also true. all ways will work. but using 1 and 3 is probably better standard practice.

[devnulljp]

Might find this useful: http://www.sengpielaudio.com/calculator-paralresist.htm

I have to do this with old Maestro wahs to change a HotPotz down to ~25k.

[morange]

Yup... along with a slight alteration in taper.

Or huge, depending on the values.
It's a good way of testing if you need a different value, though!

explain
i need scenarios

In the chart, the non-colorful numbers are the total resistance (k), when the pink and the blue are in parallel.

Parallel.JPG (63.13 KiB) Viewed 1603 times

The graphs show a few examples.

10k.JPG (25.99 KiB) Viewed 1603 times

100k.JPG (23.24 KiB) Viewed 1603 times

1M.JPG (26.92 KiB) Viewed 1603 times

[McSpunckle]

Woah! Graph overload!

If you look at the graph with the 10K parallel resistor, you'll notice how steep the curve is as you change pot value. That would also translate to the taper of the pot, so that as you turn the pot down, it won't do much, then do everything all at once, basically.

It still WORKS, just has a really awful taper.

[eatyourguitar]

I guess the rule here is that the resistor should be the same or bigger than the pot. like 1m9 + 250k pot is almost completely linear. I got lucky on this one.