potentiometers

[gstopp at fibermux.com]

     The best thing to do is to find a great big electronic surplus 
     warehouse in your town. If you must go 100 miles, so be it. Ask 
     around, look in the yellow pages, call around, drive around, just find 
     it. There's got to be one in every major city. Some people will not 
     reveal the location of their favorite place because then the parts 
     will get scarfed up. Besides, finding these places is part of the 
     learning experience.
     
     You should be able to find a box of pots that will work. If I find a 
     box of 100K linears for .50 each, and I like them, I'll buy a hundred. 
     Yeah it's fifty bucks but if you think you're gonna be a builder you 
     might as well cough it up. Things I look for:
     
     Feel - smooth gliding turn from min to max. Not too much effort, but 
     not floppy like it's loose inside. No scratching or grinding or 
     crunching. Wirewounds allowed only for small values (100 ohms or 
     below, besides I never need that kind anyway so it's not an issue).
     
     Shaft - 1/4", at least 1/2" sticking out. Longer is okay, that's what 
     hacksaws are for. Flat side is not a problem. Nylon splined okay if 
     there's most of 1/4" of meat there. Plastic okay. If I get to choose 
     I'll take a 1/2" long metal flat-sided, since that means I can use 
     them as-is and won't have to make 100 cuts with a hacksaw.
     
     Value - 100K is my favorite. 50K will do. 10K I'll buy (but not a 
     hundred, maybe ten). 1M are important for lag circuits and envelope 
     generators - these are less common, so if you find some and they're 
     decent then buy even more.
     
     Taper - linear is the most flexible for general use. You can use a 
     linear even if the application is calling for an audio or a log - it 
     won't be ideal but it will work. However using an audio or log where 
     it's needed is always a good thing. If you know what you want and you 
     find it, buy it.
     
     Mounting bushing - 1/2" deep is the best compromise. Diameter not too 
     critical. Be sure you can find the nuts, if they aren't included - 
     hopefully the pots will have the nuts included. Then you don't have to 
     spend extra to buy those. Washers are icing on the cake - if good 
     washers are part of the deal then buy even more. Washers are important 
     when mounting to avoid wrench/socket scratches on the panel. I do not 
     buy pots that have no bushings, like PC mount. I can't use them.
     
     Solder lugs - those little ring-shaped solder lugs are the best. 
     PC-mount legs are okay. No matter what is there, you can usually just 
     solder on a wire with no problem. Center-tap terminals are rare and 
     can be extremely useful - be on the lookout for those! You can leave 
     it un-connected and the pot will function normally.
     
     My "dream" pot would be a 100K smooth-turning center-tapped linear pot 
     with 1/2" bushing, nut and washer, and a 1/4" metal flat-side shaft 
     that's 1/2" long, for .50 apiece. Not that I sit around and dream 
     about pots, but there ya go.
     
     I hate slide pots for anything other than replacing broken slide pots 
     on ARPs. I can't easily make slots in panels so I don't like them. 
     Others may like them, go ahead, you can have them.
     
     Duals, concentrics, and other weirdos can be useful for certain things 
     and so I keep a drawer-full of those around just in case, but I don't 
     buy them unless I'm looking for them.
     
     Another great source of pots - garage sales! Snap up those old 
     stereos! Talk about center-taps and duals and concentrics - old 
     stereos are full of those! Usually the knobs are goofy and should be 
     tossed. But the pots are usually in fine shape and quite useable. 
     Prices can be excellent. However care must be taken not to strip out 
     anything that may be a classic, like most old tube amps (Dynacos, 
     Fishers, etc.).
     
     - Gene
     gstopp at fibermux.com


______________________________ Reply Separator _________________________________
Subject: potentiometers
Author:  mute at ma.ultranet.com (Solipsist Nation) at ccrelayout
Date:    11/19/96 10:06 AM

     So, here I am with a couple of big boxes of knobs (for 1/4" shafts), 
     but no potentiometers upon which to place them. Can anyone suggest a 
     decent type of pot to use for the ASM-1?