madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: soldersqueeze on April 14, 2013, 07:49:37 PM

Title: Harbinger speed pot
Post by: soldersqueeze on April 14, 2013, 07:49:37 PM
If I can't get hold of a 100kC dual-gang pot can I wire a 100kA pot in backwards and use it in reverse? Would it make any difference in response?
Title: Re: Re: Harbinger speed pot
Post by: jimilee on April 14, 2013, 08:46:06 PM
I've looked at the curves and they are the same except reversed.
Title: Re: Harbinger speed pot
Post by: nzCdog on April 14, 2013, 09:14:56 PM
Linear (B) is probably the best alternative.  'Reverse Audio Taper' is often confused as an Audio taper wired backwards... that's not the case.  Taper is simply the change in resistance for change in rotation, and can be represented in a graph to help you understand how they behave.

(http://www.geofex.com/article_folders/potsecrets/pottaper.gif)

You can read RG Keen's article on Pots here (http://www.geofex.com/article_folders/potsecrets/potscret.htm) if you wnt to understand pots better
Title: Re: Harbinger speed pot
Post by: soldersqueeze on April 14, 2013, 09:47:44 PM
I don't see how the graph doesn't show (for example) the resistance between legs 1 - 2 of a reverse log pot at 30% rotation wouldn't match up with legs 2 - 3 of a log pot at 70% rotation, but i'll read the article again anyways  :'(
Title: Re: Harbinger speed pot
Post by: nzCdog on April 14, 2013, 10:42:51 PM
Sorry I guess I missed the point of your original question Soldersqueeze... my bad ::)  Type A taper will have the same response wired backwards, only it will operate in the opposite way; so if turning right with C Taper sped things up, now turning right will speed things down :)
Title: Re: Re: Re: Harbinger speed pot
Post by: jimilee on April 15, 2013, 12:59:09 AM
Quote from: nzCdog on April 14, 2013, 10:42:51 PM
Sorry I guess I missed the point of your original question Soldersqueeze... my bad ::)  Type A taper will have the same response wired backwards, only it will operate in the opposite way; so if turning right with C Taper sped things up, now turning right will speed things down :)
This
Title: Re: Harbinger speed pot
Post by: soldersqueeze on April 15, 2013, 06:47:39 AM
Thanks guys

So to confirm- I can use the 100kA if I can't find a replacement then? Wiring pad 3 to lug 1, pad 2 to lug 2 and pad 1 to lug 3 and using it so clockwise rotation slows the speed?
Title: Re: Harbinger speed pot
Post by: nzCdog on April 15, 2013, 09:43:50 AM
Yup :)

Smallbear stock a 100KC Dual gang fyi
http://www.smallbearelec.com/servlet/Detail?no=1032 (http://www.smallbearelec.com/servlet/Detail?no=1032)