Turn a log pot into a (kind of) linear pot

osterchrisi · 12th October 2011, 10:56 AM

Hey there!

I made a terrible mistake in a circuit that I have to fix now: I ordered 250 wrong potentiometers (logarithmic scale) but they should be linear. Ordering new ones is not an option as this would take 8 weeks to wait for but we start production next week.

Is there ANY way of hacking a logarithmic pot into a linear-like one? The resistance value is 100K but I also wouldn't mind loosing part of this range, to like 50K or whatever.

Any clue anyone?

PS: Cross-posted this also on the electronics point forum for desperateness' sake...

osterchrisi · 12th October 2011, 11:28 AM

Mhm, thought I attach some more info: The log pot is actually responsible for setting the speed of a 555 timer (you know, between Trigger and Discharge). So maybe there are more possibilities of changing the logarithmic behaviour of the setup?

mickeymoose · 12th October 2011, 01:12 PM

Look at pix 3a and 3b, making a lin pot into "log". This should help you linearize your pot. E

osterchrisi · 12th October 2011, 01:24 PM

Thanks, mickymoose!, I know that trick already, works really nice

But I want to perform the opposite: Converting a log pot into a lin pot...

Frank Berry · 12th October 2011, 01:40 PM

You can convert log to lin if you follow the "B" schematic.

12th October 2011, 10:56 AM	#1
osterchrisi diyAudio Member Join Date: Jun 2011	Turn a log pot into a (kind of) linear pot Hey there! I made a terrible mistake in a circuit that I have to fix now: I ordered 250 wrong potentiometers (logarithmic scale) but they should be linear. Ordering new ones is not an option as this would take 8 weeks to wait for but we start production next week. Is there ANY way of hacking a logarithmic pot into a linear-like one? The resistance value is 100K but I also wouldn't mind loosing part of this range, to like 50K or whatever. Any clue anyone? PS: Cross-posted this also on the electronics point forum for desperateness' sake...

12th October 2011, 01:40 PM	#5
Frank Berry diyAudio Member Join Date: Sep 2003 Location: Midland, Michigan	You can convert log to lin if you follow the "B" schematic. __________________ Frank

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12th October 2011, 11:28 AM	#2
osterchrisi diyAudio Member Join Date: Jun 2011	Mhm, thought I attach some more info: The log pot is actually responsible for setting the speed of a 555 timer (you know, between Trigger and Discharge). So maybe there are more possibilities of changing the logarithmic behaviour of the setup?

12th October 2011, 01:24 PM	#4
osterchrisi diyAudio Member Join Date: Jun 2011	Thanks, mickymoose!, I know that trick already, works really nice But I want to perform the opposite: Converting a log pot into a lin pot...

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