My fan worked fine, so I gave it WiFi

Re:My fan worked fine, so I gave it WiFi by _ihaque on Tuesday November 11, 2025 @04:39PM (#45893239)

Based on the description of the wiring to the motor (24V, GND, POT1, POT2, NC), it doesn't sound like the original setup would have been drawing much power through the pot either -- there's probably something else on the other end of that wire that is doing modulation based on the sense resistance, and the motor is itself drawing power from the 24V line. So while it's true that there should be a check for the allowable limits on the digipot, I don't think it's actually being used to sink much power.

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Re:My fan worked fine, so I gave it WiFi by announcer4614 on Tuesday November 11, 2025 @04:41PM (#45893259)

Hey, author here. That's correct. The potentiometer has 5V going through it, with a current range of 30-164μA, which fell within limits of the digipot. I opted to use the digipot instead of my own PWM because something else must be doing PWM closer to the motor, where I didn't want to go modifying.

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Re:My fan worked fine, so I gave it WiFi by ttshaw1 on Tuesday November 11, 2025 @05:22PM (#45893703)

You're right, I didn't read thoroughly enough.

>Everything joined up via a 2-pin and 5-pin connector on the PCB. From there, it was a straightforward matter of measuring voltages and continuity to work out what connected to what: the 2-pin connector was offering 24V DC. The 5-pin connector was what went off to the motor itself. Two of its pins were passing through the 24V DC and ground directly. Two more pins were connected to the potentiometer. The fifth pin was not connected.

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Re:My fan worked fine, so I gave it WiFi by 05 on Tuesday November 11, 2025 @04:42PM (#45893272)

> there's probably something else on the other end of that wire that is doing modulation based on the sense resistance

And it would have been great if that arbitrary assumption had been tested by the OP and the results were documented in the article so that they wouldn't come off as somewhat clueless as to the limitations of their design.. oh well.

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Re:My fan worked fine, so I gave it WiFi by anamexis on Tuesday November 11, 2025 @05:17PM (#45893637)

From the HN guidelines:

> Be kind. Don't be snarky. Converse curiously; don't cross-examine. Edit out swipes.

> Don't be curmudgeonly. Thoughtful criticism is fine, but please don't be rigidly or generically negative.

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Re:My fan worked fine, so I gave it WiFi by TylerE on Tuesday November 11, 2025 @06:02PM (#45894108)

These passive aggressive posts are a far worse violation of the HN Guidelines than what they're in reply to almost all of the time - and this is no exception.

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Re:My fan worked fine, so I gave it WiFi by knappe on Tuesday November 11, 2025 @06:19PM (#45894261)

No, no they're not. I would much rather people are warned about the guidelines and adhere to them going forward than the opposite and we then just let violations run rampant.

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Re:My fan worked fine, so I gave it WiFi by TylerE on Tuesday November 11, 2025 @06:32PM (#45894378)

They're not "warnings". They're passive aggressive internet dick waving virtue signalling. The flag button exists.

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Re:My fan worked fine, so I gave it WiFi by wizzwizz4 on Wednesday November 12, 2025 @01:18AM (#45896909)

I, for one, appreciate knowing why people have flagged my comments. The "flag and move on" strategy is for use against bad actors.

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Re:My fan worked fine, so I gave it WiFi by bsder on Tuesday November 11, 2025 @06:00PM (#45894084)

There are a lot of people who read or watch stuff from the Internet and then play with mains voltages without giving a though to how dangerous that is.

See: any craze which uses the high voltage transformers from microwaves

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