cheap linear digital pot search

xplod1236 · 28th September 2004, 10:36 PM

I need some help finding a cheap digital pot( I need 14 of them). It will be used in an adjustable low pass filter, so it needs to handle ac (+/-). I don't want to use the pga2310, because that pot is logarithmic and not linear. I would prefer serial control and a dip package.

Does anyone have any suggestions?

dmfraser · 28th September 2004, 11:20 PM

www.maximic.com

xplod1236 · 28th September 2004, 11:24 PM

I already looked thru that site. I was looking for specific ones tho.

johnnyx · 28th September 2004, 11:47 PM

I think it depends on how many steps you need on the wiper. I was thinking about this too; there is a circuit idea in Electronics World that uses digital pots to set the frequency and Q of 2nd order state variable filters. It uses 256 step pots, and is scaled to give fs = 1 to 256Hz, and Q = 0.01 to 2.56. I thought an active crosover design using these would be very versatile, but (and there's always a "but") each stage uses 8 op amps and four pots; one for Q, two for f and one for level.

One thing I found on searching for suitable devices is that no distortion figures are given, so I'm not sure about their suitability for audio circuits. If they're anything like CMOS switches then they aren't that good.

We need someone with experience.

xplod1236 · 29th September 2004, 01:52 AM

Quote:

I think it depends on how many steps you need on the wiper.

That doesn't really matter for a sub filter. 256 would be nice, but 64 would work too.

Quote:

Originally posted by johnnyx
...and four pots; one for Q, two for f and one for level.

The circuit that I want to build uses 8 pots; 4 for f, one for q, one for phase adjustment, one for boost, one for boost frequency, and one for volume.

I will replace the volume pot with the pga2310, and all the other pots with digital ones. I want to build 2 of these (stereo), but I do not want to turn 20 pots to adjust one setting.

Edit: I checked out maxim again, and I found these 2 pots that would work: DS1868 and DS1267 . I found the DS1868 for $2.53 (if i buy 125 of them) and the DS1267 for $8.32, both at digikey.com.
Is that the cheapest I will get them for, or is there some other place that sells them cheaper?

28th September 2004, 10:36 PM	#1
xplod1236 diyAudio Member Join Date: Dec 2003 Location: On the couch	cheap linear digital pot search I need some help finding a cheap digital pot( I need 14 of them). It will be used in an adjustable low pass filter, so it needs to handle ac (+/-). I don't want to use the pga2310, because that pot is logarithmic and not linear. I would prefer serial control and a dip package. Does anyone have any suggestions?

28th September 2004, 11:20 PM	#2
dmfraser diyAudio Member Join Date: Dec 2003 Location: Orange County, CA	Look at the Maxim web site www.maximic.com __________________ Dan Fraser

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28th September 2004, 11:24 PM	#3
xplod1236 diyAudio Member Join Date: Dec 2003 Location: On the couch	I already looked thru that site. I was looking for specific ones tho.

28th September 2004, 11:47 PM	#4
johnnyx diyAudio Member Join Date: Jan 2004 Location: manchester	I think it depends on how many steps you need on the wiper. I was thinking about this too; there is a circuit idea in Electronics World that uses digital pots to set the frequency and Q of 2nd order state variable filters. It uses 256 step pots, and is scaled to give fs = 1 to 256Hz, and Q = 0.01 to 2.56. I thought an active crosover design using these would be very versatile, but (and there's always a "but") each stage uses 8 op amps and four pots; one for Q, two for f and one for level. One thing I found on searching for suitable devices is that no distortion figures are given, so I'm not sure about their suitability for audio circuits. If they're anything like CMOS switches then they aren't that good. We need someone with experience.