Hi, I am getting log pots (audio pots) very cheap. Is there a way to convert this to linear ones?
I've seen a few designs on the net that convert linear to logarithmic by adding a resistance or two, but not any for the other way round. Is this doable by similarly connecting a resistance?
Thanks, Venkat.
In short, no. If you want linear, buy linear.
Bob M.
Not that I've ever heard of. Adding resistances to convert linear to log is pretty easy, but as far as I'm aware, converting log to linear would require physically reworking the resistance element of the pot. Dunno about you, but that's a task that's *WELL* beyond my skill... (Well, OK, maybe not "beyond" - I'm sure I could hack on a pot and alter its performance, but I wouldn't count on the results being anywhere near reproducible or predictable, which probably eliminates any usefulness...)
-- Don Bruder - dakidd@sonic.net - If your "From:" address isn\'t on my whitelist, or the subject of the message doesn\'t contain the exact text "PopperAndShadow" somewhere, any message sent to this address will go in the garbage without my ever knowing it arrived. Sorry... for more info
If you are gettin em for half price, hook 2 of em up back to back to cancel each other out.
It probably won't come out perfectly linear, but you could straighten it out some by attaching a resistor to the wiper and one of the legs. Start with a resistor about one fifth the pot resistance and experiment. Let us know what happens.
How?
On a linear pot, each degree of rotation of the shaft has an equal resistance change. On a log pot, that change of resistance per degree of shaft rotation varies.
You can "syntheisze" a log pot with a resistor from the arm to one of the fixed ends (for discussion, we'll assume the ground end) of the pot because that resistor will be swamped out as the arm gets closer to ground (where the resistance from the arm to ground becomes less). Move the arm up towards the free end, and the resistor from the arm to ground will have more of an effect on the resistance of the pot.
But if add a resistor to a log pot, as the poster is asking, you will get the same effect, only magnified. Not only will the pot be logarthmic, but the resistor will add to the effect.
Michael
Listen, I know he's not going to get a true linear pot but he can fake it.
Set the log pot at its physical midpoint. Take resistance measurements from the wiper to the endpoints of the pot, call them R1 and R2. Get a resistor with a value approximately equal to the absolute value of R1R2/(R2-R1). Connect this resistor between the wiper and the end of the pot where you measured the higher resistance, you now have a pot with a resistance centered at its physical midpoint.
Yes, probably crappy. But what's the harm? If the guy wants to take log pots and try to "convert" them, let him.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.