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DIY Stompboxes => Building your own stompbox => Topic started by: toneless on April 01, 2004, 06:42:03 PM

Title: How can I make a reverse log pot?
Post by: toneless on April 01, 2004, 06:42:03 PM
Hi.I'm trying to make a reverse log potentiometer.Does anybody know how can I do this? I've read the "secret life of pots" article at geofex.com
but my english are not very good -my math aren't either- and there are
no examples in the article :(

Let's take a 100k linear pot as an example.What taper resistor shall I
use and where I must connect it?

Thanks in advance
Title: How can I make a reverse log pot?
Post by: brett on April 01, 2004, 07:19:06 PM
Hi.

If you are using the pot as a variable resistor (e.g. the "drive" pot in the RM Axis fuzz) then you can use lugs 2 and 3 of a log pot.

If it's being used as a voltage divider (all 3 lugs are used), then you can connect a resistor fom lug 2 to lug 3.  For a log taper, the resistor should be about 1/3 of the pot value (eg 100k pot, 33k resistor).  That makes a 33k reverse log pot.

To make a 100k reverse log pot, start with a 250k pot and use a 100k resistor.

(by the way, a linear pot doesn't usually sound too odd in place of a reverse log pot)

hope this helps
Title: How can I make a reverse log pot?
Post by: brett on April 01, 2004, 07:23:40 PM
Oops.  I think I got the lugs wrong.  The geofex article will explain which lugs. sorry  :oops:
Title: How can I make a reverse log pot?
Post by: toneless on April 01, 2004, 08:08:51 PM
Ok!Thanks.
I think I've got it now.