Converting audio pots - linear?

[H4T]

I recieved my parts for the Nurse Quacky today, sans copper-clad board (stupid me >_<), and I realized that I stupidly ordered audio pots, instead of the linear the schematic calls for. This was before I knew the difference, now I do.

Is there anything I can do to have these pots work as linear pots, or will the difference be mostly negligible? Maybe a simple circuit before the pot, or take apart the pot and mess with the inner windings? Feel so stupid, but can't afford to go out and buy 3 new linear pots >_<

[niftydog]

Is there anything I can do to have these pots work as linear pots

If it was simple and effective, we'd all be doing it. Sadly, it's just not possible - at least, not simple.

You can sometimes open up the pot and change the carbon tracks, but you've gotta have the right carbon tracks to begin with!

Stash them away, you'll no doubt use the one day in the future.

[H4T]

Hm, I rechecked my order request (from Small Bear) and on it I did indeed order linear, not audio pots. I was confused because the labels on the backs of the pots are rather misleading.

Looking at the bottom of the pot, I see a "a" in a circle, then underneath it is "ALPHA B25K." The "a" in the circle I thought meant "audio" but I wasn't sure.

I trust that my order was fulfilled correctly :\ lol

[Melanhead]

Yup! ... the "b" means linear ... build away

[toneman]

use an ohmmeter to verify the taper.
an analog meter works best.
RatShack has several, under $10 analog meters.
when in doubt, ohm it out....
T

[H4T]

Ah yeah, I really need to get one of those, lol. Seems whenever I get my hands on $10 or more bucks I blow it on parts, haha, I need to get a multimeter sometime.

Glad I got that figured out, now I gotta buy me some copper-clad board. Which no place in town carries apparantly, not even Ratshack, gwar.

[Paul Marossy]

Most of the time, you can use log pots on most circuits with no adverse effects. Tone controls, gain controls, etc. The opposite is not always true, though, especially for a volume control. A linear pot as a volume control is way too abrupt to be real practical in most cases.

[H4T]

Yeah, thats something I'll have to experiment with someday, but this circuit will need linear pots for "Attack," "Range," and "Sensitivity." I think all of those would work best as linear pots, which is why I didn't really like to think I had audio pots. I could use audio pots, but I don't think they'd be as good as linear in this situation.

[Paul Marossy]

Well, I said most circuits. At least the distortion type circuits.  :wink:

[MartyB]

Check these multimeter deals out:

http://order.harborfreight.com/EasyAsk/harborfreight/results.jsp

[H4T]

Yeah those would be great deals in real life, but the problem with anything online-based is you have shipping an handling. That site wants $6.99 for shipping an handling, almost doubling the price of the lowest $10 meters. I hate shipping and handling >_<

[jra2217]

Yeah those would be great deals in real life, but the problem with anything online-based is you have shipping an handling. That site wants $6.99 for shipping an handling, almost doubling the price of the lowest $10 meters. I hate shipping and handling >_<

i hate tax .

[toneman]

*****Check these multimeter deals out: *****

I said "Analog"........U know, the one with the little moving pointer.

Harbor Freight lists no analog meters....only *digital*.
I have several of the little $4 digital meters.
They are fine...even come with a 9V batt!!
But, to measure the taper of a pot, U *need* analog.
If i say "analog" one more time.....i'm gonna .....
T

[Johnny Guitar]

But, to measure the taper of a pot, U *need* analog.

I don't know about this. What I've done in the past is verify the pot value (leads to the outer lugs) and then leaving one lead on one lug, move the other lead to the wiper. Crank the pot all the way around until you measure 0 ohms. Now, noting the orientation of the pot shaft (or by using a knob with a marker line) check it at 3 places: 1/4 of it's movement (less than a 1/4 turn of the pot since most pots have only 270 to 300 degree rotation), 1/2 of the pot's movment, 3/4 of the pot's movement.

A linear pot will have almost exactly equal divisons of the pots value. An audio pot will have radically different values for each partial turn.

I use a DMM all the time to do this.

[puretube]

courtesy R.G. Keen (GeoFex):

http://www.geofex.com/Article_Folders/potsecrets/potscret.htm

[travissk]

If you keep blowing $10 on parts, just save up $50 to blow on parts and get a free DMM from circuitspecialists.com (web-tronics.com if you're outside the USA)

[toneman]

PT & Johnny,
U both R right.
Half travel, shouldB half R w/linear pot.
i'm just sooo used 2 watching the little pointer move up
and down "linearily"   :lol:
my mantra:
stayohmmmmmmm(ed)
tone

[MartyB]

del

[MartyB]

*****Check these multimeter deals out: *****

I said "Analog"........U know, the one with the little moving pointer.

My suggestion wasn't addressing you or your comment Toneman.  H4T said he needed a multimeter.

Ah yeah, I really need to get one of those, lol. Seems whenever I get my hands on $10 or more bucks I blow it on parts, haha, I need to get a multimeter sometime.

My suggestion was to check Harbor Freight's prices H4T.  I have two of their retail stores in my area so shipping isn't always an issue.  YRMV.   As  Travissk said you can also get a very handy DMM with transistor hFe test function for free with a large-enough order from Circuit Specialists in Arizona.  I kept and use mine - gave my old one to my dad.  I have an analog Micronta meter but don't find any use for it.

[puretube]

tone: recently asked my lovin`wife to bring me 2 ana-meters from a clearing-sale (§2.75, each) - love them for monitoring slow LFOs, LDR- and `lytic cap circuits...  

by now, I got used to the slow reaction of DMMs when it comes to checking lin/log "halfwayrotation"- measuring...  :lol: