counter clockwise log pot?

[homer09]

i want to design an amp with mono volume controls. i think its much more natural for the left control to be counter clockwise and the right control to be clockwise. so, when adjusting volume, you can grab a knob in each hand and turn outwards from the center. a more natural movement, and hence easier adjustment.

now, its easy to switch the direction for a linear pot, a simple switch of leads and yer set. but volume controls are logarithmic, and you cant just switch a log pots direction, right? If you switch leads, then in the middle wiper setting you would have ~80% Vin instead of ~20%.

SO, how can i switch the direction on a log pot?

[gmphadte]

If it is not available, make ur own fixing the shaft from behind. May not be easy but it's a solution one can try, u know...

Another solution, gear drive...

Gajanan Phadte

[richie00boy]

You need an antilog pot. I would just use lin pots with law faking resistors.

[homer09]

Yup, fake lawing was my initial idea. im sure richie you know that from the other post i made recently. I was looking for a fresh view i guess.

speaking of the other post, you didnt end up replying. lets say i choose a 10:1 ratio for pot and fake law resistor, how should i go about choosing the values of the pot? What i mean is, what is the difference between choosing a 250K pot with a 25K resistor or a 500K pot with a 50K resistor? I know input impedence will change but the pot law will stay the same. How do you recommend i choose? or does it even make a difference...

[richie00boy]

Sorry, I obviously missed your question in that thread. The choice comes down to the simple matter of impedance and compromise. Too high and the noise will be noticeable and susceptibility to RF and interconnect capacitance higher. Too low and you load the source too much. I use 100k pots purely because they are always easy to get.

PS I would like a copy of that spreadsheet where you tested the different pot/shunt values, if you are still giving it away Click the email button.

[homer09]

Richie, i cant attach to emails sent through the forum, so i attached it in the other thread, since i think its more appropriate there.

*technical elec question* DC offset/input impedance relation

[richie00boy]

The idea was that you click my email button, I get an email then I reply to you so you get my address But no matter now as I got it from the post you linked Thanks