# Examples of digital potentiometer and Arduino

I have been trying to operate a digital potentiometer IC with Arduino. The digital potentiometer is a MCP4231, and actually contains two individual potentiometers. There are examples of the MCP4231 operated with Arduino, operating LEDs on the Internet. There are examples in the Jeremy Blum book--"Exploring Arduino" using the MCP4231 potentiometers in rheostat form, operating LEDs.
Here is where I think all of these examples are totally crazy: If you go to the data sheets of the MCP4231---"Absolute Maximum Ratings" The maximum current any of the potentiometer pins can have is +/-2.5mA. In these examples mentioned above, Arduino and the MCP4231 IC operate the potentiometers. The potentiometers are connected to LEDs with 220 ohm resistors. The potentiometers terminals are powered with 5 volts DC. The potentiometer wipers have a internal resistance of around 100 ohms. By Ohms law the current then would be 5 divided by 220+100=.0156. In mili-amps that would be 15.6mA That is way more current than the absolute maximum listed in the "Absolute Maximum Ratings" of the MCP4231. Meaning: 15.6mA is much more current than the absolute maximum rating of 2.5mA. So I ask this question: How in the world could these examples possibly work?
In breadboarding the examples mentioned above, and running the code in these examples, you get screwy results. Meaning the examples don't work. So why are these examples on the Internet and in books? Am I missing something?

Hmmm this seems all too familiar. Isn't this a repeat question? Yes, it is.
https://forum.arduino.cc/t/mcp4231-digital-potentiometer-circuit/923731

Yes, aarg it is a repeat of sorts. But it is not a repeat of my question; Why are these examples listed in a quality book like Exploring Arduino? Examples done so formally on the internet? I have found zero examples of the MCP4231 and Arduino that stays within the 2.5mA current limitation.

Did no one ever tell you that you can't believe everything you read? A modern expansion of that would be to not believe everything you find on the internet.

Using a digital pot as a voltage divider to fade an LED is just so not the way to go that it hurts to think about.

What is the end-to-end resistance of the digital pot? You can't use a 10K pot of any kind in this way. Digital won't make it work any better.

Supply a link to a or the website where this is taught. I am no doubt missing something or misinterpreting.

OK I found an instructables and there is video so cold me amazed - that just should not work at all.

What is your ultimate use for the digipots? If it in fact to just fade en LED, there a good ways to do that without anytinh but an LED and a current limiting resistor.

If you are just using an LED to verify that you are controlling the digipot, hanging a voltmeter off the wiper would be better.

Or it's getting too tired and I am really late.

a7

So the take-home message is that "digital potentiometers" are absolutely not intended for dimming LEDs notwithstanding anything you might read on the "instructables" site.

Which site one contributor here has described as people with negligible knowledge of electronics and engineering trying things of varying degrees of safety and if the components actually survive for over five minutes and give some appearance of doing what they wished, they write it up as a project".

Instructibles is not a peer reviewed journal.

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