Replace Mechanical Pot with Digital

[mech3d]

First, thanks to those who have helped me in the past, much appreciated.

I would like to replace rotary pots with a digital pot to control volume.

I included the section of the schematic showing the potentiometer section.

I basically have (2) single pots and (1) dual-ganged pot.

I was looking at the maxim-ic device but there is a lot to choose from.

So what's the question, is there any guidelines to follow? Are these drop in or do you need supporting circuitry? I think you at least will need small push action switches to control the pot's steps. And then there is the question of using volitile or non-volitile.

This is sort of new to me so please don't mind my ignorance.

Thanks,
Joe

 

[mech3d]

The pots in the schematic are P1 and P3, the dual-ganged pot P3 is not shown.

 

[dawhale]

Maybe R1 is mis-labeled? I couldn't find it either
DD

 

[crutschow]

I don't think there are any direct drop-in digital pots for analog pots.

The volume control in modern electronics often uses a digital rotary control to generate up or down pulses. These pulses go to a digital potentiometer (chip) to control the volume. You could also use push buttons to provide the up/down pulses.

Non-volatile digital pots are used for permanent one-time (or a few times) setting of the pot (such as would be used for calibration of a device). They also can be used to retain the volume setting when the power is removed.

 

[mech3d]

Ooops,

I meant P1 and P2 are shown. R2 is at the 2M2 at the top of the schematic.

 

[MRubenzahl]

Reply from Maxim re digital pot choices

I saw your posting on Electro Tech site in which you had several questions relating to replacement of mechanical potentiometers with digital potentiometers and noted that you had already visited the Maxim website. Welcome!

I asked our technical support to take a look at the question and here is what they said:

Maxim does offer quite a few potentiometer solutions. Narrowing the search to the best of these can seem daunting at first but is actually as easy as identifying the application requirements*and then contacting Maxim's Technical Support group. Or you may use Maxim's*interactive parametric search engine to define the best component to meet your circuit needs.

You may look up our web site for application notes AN3417, AN4101, and AN1828 "Digital Potentiometers Replace Mechanical Potentiometers", "Differentiating Digital Potentiometer Features", and “Audio Gain Using Digital Potentiometers”. These application notes provide valuable information on how to use our potentiometers.

To answer your questions specifically, there is no “drop in”. Supporting circuitry is needed. You need a push button switch if you do not use a microcontroller. You may choose a non-volatile device if you want the device to power up to the previous value.

Please feel free to visit Maxim's online Technical Support site where we will be happy to review your circuit and offer*suitable component recommendations.*

 

[mech3d]

Thanks for your help but when I contacted Maxim all they said is we don't have a 5K digipot and offered no other assistance except to look at some application notes.

I was hoping they would have said "you can use XYZ as an alternative if you change these resistors in your schematic" but that didn't happen. Maybe I was asking too much.

Well, this is above my knowledge so I am still lost.