Using a pot to control a digital pot

Bill Fitzpatrick · 23rd March 2004, 05:54 PM

I'd like to forego the controller chip and use a single pot to control several digital pots. Does anyone have experience or info on this?

macboy · 23rd March 2004, 06:36 PM

In theory, this should not be difficult.
Use the pot as voltage divider with stable voltage reference and suitable filter on the output (say 47K and .22 uF). The pot's output would feed into a microcontroller with an ADC. You might want to apply a digital filter of some kind to this input as well. The micro then calculates the appropriate value to write to the pots to give the desired attenuation. Same value to all pots. I'd use a PIC because they are easy to use and many include the ADC plus I2C and SPI peripherals needed to communicate with the digital pots.

Bill Fitzpatrick · 23rd March 2004, 07:01 PM

You missed the point. I want to avoid controller chips. I just want to use a pot as a voltage divider to control a digital pot chip directly.

mikewu99 · 23rd March 2004, 08:10 PM

Doesn't use a pot as the control, but eliminates the microcontroller:

http://www.maxim-ic.com/appnotes.cfm...mber/606/ln/en

If you're really set on the analog pot as a control you'll need some sort of A/D converter plus some glue logic to convert the ADC output into the proper format for the digital pot. Unless you get really lucky and find an ADC with a serial output that is exactly the right format for the digital pot input...

tool49 · 23rd March 2004, 08:25 PM

http://www.elecdesign.com/Articles/I...rticleID=2531#

Check this one out, I've built it and it works! but I went back to the microcontroller to be able to use the better chips. (i.e. PGA2310)

Sébastien

23rd March 2004, 05:54 PM	#1
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	Using a pot to control a digital pot I'd like to forego the controller chip and use a single pot to control several digital pots. Does anyone have experience or info on this?

23rd March 2004, 08:10 PM	#4
mikewu99 diyAudio Member Join Date: Jan 2003 Location: Audubon, PA	Doesn't use a pot as the control, but eliminates the microcontroller: http://www.maxim-ic.com/appnotes.cfm...mber/606/ln/en If you're really set on the analog pot as a control you'll need some sort of A/D converter plus some glue logic to convert the ADC output into the proper format for the digital pot. Unless you get really lucky and find an ADC with a serial output that is exactly the right format for the digital pot input... __________________ Mike "Never confuse motion with action." B. Franklin

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Digital Volme Control	elnino86	Parts	27	28th April 2009 05:27 PM
digital volume control	neazoi	Parts	1	21st April 2009 08:56 AM
Digital volume control	maharadza	Digital Source	9	8th April 2006 04:59 PM
digital volume control	Pulse-R	Digital Source	4	5th April 2005 01:33 PM
Digital Volume control for in Car use	dunderchief	Digital Source	7	28th March 2004 12:08 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

23rd March 2004, 06:36 PM	#2
macboy diyAudio Member Join Date: Oct 2003 Location: Ottawa, Canada	In theory, this should not be difficult. Use the pot as voltage divider with stable voltage reference and suitable filter on the output (say 47K and .22 uF). The pot's output would feed into a microcontroller with an ADC. You might want to apply a digital filter of some kind to this input as well. The micro then calculates the appropriate value to write to the pots to give the desired attenuation. Same value to all pots. I'd use a PIC because they are easy to use and many include the ADC plus I2C and SPI peripherals needed to communicate with the digital pots.

23rd March 2004, 07:01 PM	#3
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	You missed the point. I want to avoid controller chips. I just want to use a pot as a voltage divider to control a digital pot chip directly.

23rd March 2004, 08:25 PM	#5
tool49 diyAudio Member Join Date: Apr 2003 Location: Montreal	http://www.elecdesign.com/Articles/I...rticleID=2531# Check this one out, I've built it and it works! but I went back to the microcontroller to be able to use the better chips. (i.e. PGA2310) Sébastien

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)