Electronics > Projects, Designs, and Technical Stuff

Digital rules !

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DavidDLC:
I will never never use analog potentiometers again !

Well it's better to say: I will use digital potentiometers whenever is possible, of course they are more complex and expensive to use but I'm loving them !

I mean it's not the same to be turning the volume up and down or other controls on your tv knowing there is one there compared to implement one yourself, at least that is my case.

So next step will be to replace the 10 turn pot on Dave's Electronic Load for a digital one.

Dave do you have an idea of a good number of steps for a digital pot that can suitable for your project ?

Here are some pictures:

Zad:
Useful little things, but they can kinda fall into the "when all you have is a hammer, everything looks like a nail" category. Volume controls are my pet hate. Analogue (or at least rotary) controls are the optimal solution, but up/down buttons are cheap and easy to manufacture.

Bored@Work:
Well, digital pots are often used as a kludge. Your usage to regulate an LCD contrast is such a kludge. A single MCU output pin with hardware or software PWM and an RC filter would do the job for a fraction of the cost, instead of that digital pot.

Same for Dave's electronic load. No need for some digital pot junk, just one output pin, a 10 or or more bit PWM, and an RC filter into the OpAmp voltage follower.

ziq8tsi:
just wow.  i had never heard the term "digital pot", and at first i took it to mean "rotary encoder".  those are relatively expensive, but have most of the advantages of pots, plus the fact that you can turn them indefinitely in either direction.

i am totally with Zad that turning is a better user interface than clicking.  in the early 1990s it was quite common for remote controlled devices to have motor-driven analog pots so that they could be controlled locally by turning or remotely by clicking.  the move to all button interfaces quickly facilitated nasty menu-based systems like you get on modern tft monitors.

the ten turn pot in particular is a gold standard for fine user interface.  you will never reproduce the simultaneous coarse and fine control using a small number of buttons.

JohnS_AZ:
If you look inside most modern auto and home audio equipment (with volume knobs) you'll find that they actually use shaft encoders that ultimately control digital pots or the like.

There are two big gotchas with resistive analog pots; They are mechanical assemblies and thus expensive to manufacture, and being mechanical they are subject to wearing out and getting dirty (thus injecting noise and intermittent failures into whatever circuit they are controlling). 

The gotchas with digital pots are that they are pretty limited in how much current they can handle, and by definition they do not offer an infinite range of settings.  Digital pots are great for setting volume in an audio circuit, but you'll never see them used for, say, calibration points of instrumentation amps.

Resistive pots are great. Digital pots are also great. It's all about the application.

All that being said, nothing can match the feel of a big heavy knob spinning a high quality wirewound pot.  :)

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