center tapping a pot

[Dan N]

Not the most useful skill, as so few circuits use tapped pots. The Korg MS04, Ibanez PM7, and Boss PC-2 are the only ones I've ran into. Anyway, I made this fast and nasty tutorial:

http://users.rio.com/senorris/junk/ct/ct.html

Better ideas would be lovely...

[markm]

Ha!!
That's Cool!   

[stm]

Interesting! Thanks for sharing.
I understand this type of pot is key in high end equalizers.  Wouldn't know where to get one.

[The Tone God]

The same technique can be used in some amps' bias adjustment pot.

Andrew

[Dan N]

Wouldn't know where to get one.

Funny, I have an old Radio Shack dual 5K stepped pot with 40% loudness tap. Cat. No. 271-1730. It's from a lot of old RS parts, so perhaps discontinued.

[Paul Marossy]

Hey, that's a pretty cool idea! 

[Paul Perry (Frostwave)]

One thing a centre tapped linear pot is good for: more flexibility with a LFO.
instead of having a tri/square switch and a depth pot, you take the tapped pot, run square to one end, tri to the other, ground the centre tap, and now as you turn the pot the modulation goes from full square then less depth of square than no mod then the tri increases in depth. So you have saved a hole (or, you are able to make a mod without damaging the vintaj box). I have a bunch of 100K linear that were special ordered by someone on the synth-diy list, for this application.

That eyelet thing is beautiful, I have to say!! thanks for the tutorial, Dan!

[MKB]

WOW, what a GREAT idea, thanks!!  Another good application is for building an all tube graphic EQ out of a Fender Super Twin Reverb amp; a very simple circuit but uses strange center tapped pots.  Now they are available!!

[R.G.]

From "The Secret Life of Pots", GEO, 8/99

Tricks you can play

This simple structure means that there are lots of non-standard things we can do with pots.

    * if you have a brand of pot that can be reassembled, you can swap wafers between pots to repair a broken or worn out one
    * if you have a dual pot body, you can assemble custom dual pots with wafers from other single pots of that same brand
    * if you have to repair a pot and don't have another wafer, any connection you can make between the two disconnected sections of pot will work
    * you can bend the wiper contacts sideways to let them contact new, unworn areas of resistive material
    * you can bridge over breaks in the resistive material with copper or silver conductive paint, or make a custom tap point
    * I have heard that you can use copier toner dust to melt over a section of worn resistor material and repair it.

You could hypothetically scrape material off the resistor band and make a higher resistance, odd taper pot, but there are better ways to do that.

[Dan N]

* you can bridge over breaks in the resistive material with copper or silver conductive paint, or make a custom tap point

There we go. I still like the eyelet as a way to hook into the tap. 

Thanks for the response, guys!

[R.G.]

Oh, yeah! The rivet is a great way to hook to the tap. Much more solid than silver painting to a wire.