Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

My fan worked fine, so I gave it WiFi

ellis.codes

Post reply on HN
Print view View original

11–20 of 97 posts

Re: My fan worked fine, so I gave it WiFi

#11

Post by 05 »

_ihaque wrote: post #9
ttshaw1 wrote: post #6

I don't like the notion of doing speed control by putting a digipot in series with a motor. It worked because the fan happened to be low enough power but it doesn't seem like the author gave thought to the power handling capability of the digipot. If the fan happened to be beefier he's letting the smoke out with this design. Plus, this is more complicated than just doing PWM.

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 allowab…

> 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.

Re: My fan worked fine, so I gave it WiFi

#12

Post by [deleted] »

ttshaw1 wrote: post #6

I don't like the notion of doing speed control by putting a digipot in series with a motor. It worked because the fan happened to be low enough power but it doesn't seem like the author gave thought to the power handling capability of the digipot. If the fan happened to be beefier he's letting the smoke out with this design. Plus, this is more complicated than just doing PWM.

[deleted]

Re: My fan worked fine, so I gave it WiFi

#13

Post by Eric_WVGG »

kylehotchkiss wrote: post #4

Oh no don’t tell vornado this is possible and give them an enshittificafion pathway for their products

IMO anything with unnecessary digital interfaces is already down the path.

I have a Vornado fan that I would love to automate with a simple wifi-enabled plug, but due to the digital on/off/speed button, when you cut-off and restore power to the device, it stays off. If it had a dumb analog dial or switch, it would both be fine for normal use, and could be easily, cheaply made "smart."

They do sell wifi-enabled fans; none of them are in a form factor that would fit in my window.

I'm not even alone in this gripe, lots of other maniacs have done the hard work of conversions. Unfortunately I'm not confident enough in my soldering skills to try :\ https://www.reddit.com/r/electrical/comments/vaiskf/bypass_p...

Re: My fan worked fine, so I gave it WiFi

#14

Post by announcer4614 »

05 wrote: post #8

Why is there level conversion though if the digipot (MCP4141) is 2.7V to 5.5V? Personally I'd just use breadboard, it's just a 8 pin IC and a ESP module, for a one-off hack..

Hey, author here. There's a line in the digipot datasheet that says the voltage on the A/B/W pins must be within -0.3V to VDD + 0.3V. The fan's line for the wiper pin is 5V, which would fall well outside of that if I gave the digipot's VDD 3.3V.

Re: My fan worked fine, so I gave it WiFi

#15

Post by 05 »

announcer4614 wrote: post #14
05 wrote: post #8

Why is there level conversion though if the digipot (MCP4141) is 2.7V to 5.5V? Personally I'd just use breadboard, it's just a 8 pin IC and a ESP module, for a one-off hack..

Hey, author here. There's a line in the digipot datasheet that says the voltage on the A/B/W pins must be within -0.3V to VDD + 0.3V. The fan's line for the wiper pin is 5V, which would fall well outside of that if I gave the digipot's VDD 3.3V.

Thanks. Thinking more about that, might have been easier to just use 5V tolerant esp8266 :)

Re: My fan worked fine, so I gave it WiFi

#16

Post by IvyMike »

I've been toying with a variant of this project for my Honeywell home air filters. I have one in all my "big" rooms, and I like to keep them running at a low speed most of the day.

But I also have time-of-day energy pricing, and it would be nice to automatically turn off (or at least slow) my air filters during the 5pm-8pm window. This project inspires me to at least look into the feasibility of adding that functionality myself.

Re: My fan worked fine, so I gave it WiFi

#18

Post by announcer4614 »

05 wrote: post #15
announcer4614 wrote: post #14

Earlier quoted context omitted.

Hey, author here. There's a line in the digipot datasheet that says the voltage on the A/B/W pins must be within -0.3V to VDD + 0.3V. The fan's line for the wiper pin is 5V, which would fall well outside of that if I gave the digipot's VDD 3.3V.

Thanks. Thinking more about that, might have been easier to just use 5V tolerant esp8266 :)

Fair point, I hadn't thought to consider that aspect of the ESP8266. I mainly opted for the shiny new ESP32-C6 with the idea that I might one day set it up to use Thread instead of WiFi.

Re: My fan worked fine, so I gave it WiFi

#19

Post by uoaei »

I love upgrading simple home appliances with homebrew smarts using ESPHome so that they retain their original interface. I've mostly done lights that are still correctly switched at the original wall switches but up next is my fan and toaster oven! Then to tackle the thermostats.
Post reply on HN