Re: [sdiy] Potentiometer standards and the pot graph

[Roman]

	if you're talking about Bouns model 53, they were at 20cents each in electronic Goldmine at the good times when they were on sale. Well, they're all gone now :( 

	For attenuator I use something like 30:1 ratio between pot value and resistor at the wiper. That's 300k pot and 10k resistor. In reversing attenuator this gives extremely flat curve in the middle, which is convenient for setting small ammount of modulation. 

	100k resistor on 300k pot gives expo-looking curve, which is usefull for audio. If you want linear, you can always add buffer and VCA. 
	Roman, a happy owner of almost 1000 Bourns 300k pots :) 
---- Wiadomość Oryginalna ----
Od: Peng 
Do: SDIY 
Data: Wed, 15 Dec 2004 18:39:31 -0800 (PST)
Temat: [sdiy] Potentiometer standards and the pot graph

 Hi again,     I bought a bunch of Bourns 300K panelmount pots for a great deal (50 cents each!) I figured, hell...I'll use these in place of the typical 100K attenuator pots. I read something about a higher resistance results in higher noise. I don't know where I read that, or if it's actually true.   Couple days ago I was using this: http://www.mindspring.com/~clist/PotGraph.html (http://www.mindspring.com/~clist/PotGraph.html)   To my dismay, I found if I use 300K pots I'll get a response closer to exp(log?) than linear. Bummer. Then I checked 100K pot into 100K input resistor and the response is in the middle of log and linear response. Surprising. It seems the ideal attenuator pot value for 100K impedence is a 10K pot. Shouldn't this value be the standard as opposed to 100K or 50K pots for true linear response.     What do you think? Am I missing something?      BTW the 300K are good for audio mixer attenuators with the 100K impedence (oh...and the fine tune on my VCO cause it connects to a 3.3M resister,  check the graph).   Thanks for reading, P.v3 
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