Switched Pots SMD - nice price?

[conleycd]

Hey folks,

I thought this might interest people (it's an ebay link but it's the product that matters):
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160381198671&ssPageName=ADME:X:AAQ:US:1123

It is a stepped stereo 10k log pot.  21 steps.  I emailed the auction fellow.  They also have 100k, 50k, 20k.

I thought it still looks like a good price.

P.S Does anyone have a calculator for creating stepped potentiometers?  Say if I have a 21 step switcher, wanted reverse log linear - it would spit out what each resistor should be?

CC

 

[gemini86]

There are stepped attenuator calcs out there, don't know if they do reverse log though.

 

[ChrioN]

worse comes to worse, you can buy a rev log potentiometer and "match" the values

 

[abbey road d enfer]

A rev log pot is just a log pot that turns in the wrong direction 
So, if you have a log pot calculator, you use these values but wire them from top to bottom instead...

 

[abbey road d enfer]

I like that!
"Deepter depth and sweeter vocal.
Cleaner bass and sweeter treble.
Sound image is much improve. Pin point image!!!"  :'(

 

[12volts]

It doesn't get more up to date posting on a subject than this;
My stereo 10k log pot arrived from them 2 hours ago. I will admit to being sceptical but I was wrong.
It's a very tidy unit, gentle switching action and as far as I can tell, a smooth log. response. Now the bit I didn't expect -
the spacing between the 2 PCB's and the hole spacing is identical to the Ohmeg pots. This for me is engineering nirvana.
Small diameter too .....

The one down side is it has a split, splined control shaft, I would have preferred a solid, round 1/4" or 6mm shaft, but I guess you
can't have everything. For $10 these pots are a bargain. I'm off to check the availability of the linear configurations, I've got an idea.

 

[gyraf]

Good idea - but from the looks, it seems to simply be a rebuilt alpha potentiometer, meaning that the mechanics of the "switch" was probably meant for potentiometer, not for switching use. Which makes me think it won't have a very good life expectancy because the "slider" will wear prematurely from sliding on a non-even surface.

But I hope I'm wrong.

Jakob E.

 

[Ian MacGregor]

very interesting. I'm having a hell of a time finding a supplier for inexpensive dual rev log pots. I too wonder about their reliability though. Wouldn't be too hard to jig up a PIC controlled rotational tester with a PWM driven DC motor though... Do you think that the internal contacts (for the wiper) are just exposed (maybe gold plated) traces without soldermask? The wiper just drags across the exposed pad/trace? What's to keep you from just setting the pot in between a position?

I suppose there are more possibilities, such as center tapped rotary switch/pots as long as one was willing to roll their own (and I am)... Would anyone mind opening one of these bad boys up and snapping a couple shots?

ian