I haven’t tried setting max power to another other than 100%. I’ll play with it this weekend and get back to you.
I have been playing around with the settings, and it seems, the setting is used but isn’t displayed how I expected.
The pwm speed will still ramp up to 100%, but that 100% is less with the setting on. I managed to get the rpm speed recorded and see that with the max set to 70%, it maxes out at 980rpm, but without the setting it was the full 1200.
Edit: and this mistake is my first clue. 1200rpm isn’t the max, 1500rpm is. 80% of 1500 is 1200 
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It looks like the reported RPM isn’t correct. Here are my results based on testing. I need to look further into the issue.
Calc RPM=1700 * (MAX/100)*(OVRD_PWR/100)
| Min | Max | Override Power | Reported RPM | Calc RPM |
|---|---|---|---|---|
| 1 | 100 | 100 | 1700 | 1700 |
| 1 | 100 | 66 | 1784 | 1122 |
| 1 | 100 | 33 | 773 | 561 |
| 1 | 75 | 100 | 2053 | 1275 |
| 1 | 75 | 66 | 1204 | 842 |
| 1 | 75 | 23 | 496 | 293 |
| 1 | 50 | 100 | 1200 | 850 |
| 1 | 50 | 66 | 692 | 561 |
| 1 | 50 | 33 | 330 | 281 |
| 1 | 25 | 100 | 494 | 425 |
| 1 | 25 | 66 | 330 | 281 |
| 1 | 25 | 33 | 203 | 140 |
@wardy277 I finally got it figured out. I looked at the docs for the fan again here. It mentions a pull up resistor and it hit me that I needed to use a 12V pull and not the 3.3V going to the D1. Previously I was using the internal pull up resistor in code. I used an oscope to verify the frequency of the wave on D2 and plugged it into the formula from the Noctua docs. fan speed [rpm] = frequency [Hz] × 60 ÷ 2. Now that I added a 10K pull up resistor to 12V my measured values are close enough to the calculate values. 
I’ll update the OP with the latest code and wiring diagram. Notice the new 10k resistor between 12V and the yellow RPM signal from the fan.
| With 10K Pull Up to 12V | |||||||
|---|---|---|---|---|---|---|---|
| Input Speed | Freq at o-scope (Hz) | Reported Speed (RPM) | Counter from ESP LOGS Pulse/min | Count/2 | Calculated Speed (1700*input speed) | ||
| 33.00% | 23 | 694 | 1388 | 694 | 690 | ||
| 66.00% | 41 | 1245 | 2490 | 1245 | 1,230 | ||
| 100.00% | 56 | 1700 | 3400 | 1700 | 1,680 |
Thanks for your work looking into this. I don’t have enough knowledge to have worked that out
Great job
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@Stu1811 I do not think the GPIO pin will survive 12v for very long. The tachometer is an open collector and is pulled down to the ground on pulse and floating otherwise, hence the required pullup at GPIO side.
With 3.3v, the internal pullup is a lot safer.
I’m building this myself and curious to understand your comment about the 12v a bit more. Are you referring to the voltage the Tach is sending in pulses?
I just tried to test this and never saw anything over a couple of hundred millivolts, although I’m not 100% sure my testing was correct.
I cant quite get the RPM sensor working as well which is confusing me.
My recommendation about the project though would be to strip out any automation from the controller. I move all my automation into NodeRed via HA. I have complete control that way and the programs need little tweaking if ever.
Tried the multi sensor doing lots of things and found it unreliable and full of bugs. Simple is best!
I’m about to build this and was a bit baffled by your comment. Could you explain it further for those of us on the learning curve.
I would be especialy interested in a proposed solution if there is a problem,.
Thanks for any help offered
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Why is there a 10k resistor between the tacho and 12V?
Uummm…I just can’t get over this. someone made this and it has the documentation, configuration , instructions and whatever else but you can’t get it working. You then make a public service announcement that you aren’t sure why this sensor wasn’t working , but I Checked whatever this here PWM pin thing is and my meter… ya, it ain’t working right now, it’s showing a couple milivolts but, I’m not sure what I’m measuring anyway. So clearly this is because of esphome, I’m gonna quit so should everyone else and let’s go to Node Red and rebuild it from scratch!
I’m sorry man it just cracked me up. I can’t stress this enough! You need to look at data sheets (aka the instruction manual). You would have know that sensor wasn’t going to work untill you added the reccomend pullup resistor ( pullup/down resistors they don’t have anything to do with voltage or reducing voltage. They limit how much current (a) can pass through it. All of this was in that data sheet, it even tells you how to calibrate the sensors and speeds, it tells you the fan logic is inverted, so if you wanted fan speed at HIGH(100%) the gpio (inverted)needs to be OFF(0.0v) so it explains what PWM is and how it changes the speed all that fun stuff to. Read those data sheets, .man. When you understand how something works or if there’s specific details you need to be aware of , I promise it will change your whole game and cut your troubleshooting times and irritation factor way down.
I think my comment maybe slightly unclear/incomplete so I will try to do better.
ESPHome is working great for me. In this instance I used what @Stu1811 has created as a good base (Thanks again for that!) and modified it to fit my needs/wants. I had a few questions going into it though and I was looking for some help to understand some weirdness I was seeing. My testing wasn’t that in-depth and felt understanding the comments about the voltages, pull up/down resistors etc may help me to see what and how I should testing.
Now I still get unusual readings for RPM with only two exceptions. 100% and 0%. They read correctly as per the fans documented speeds but anywhere in between I get readings higher than 100% or that don’t register at all when they should be. For what its worth its a small problem and I rarely run the fan at anything less than 100% anyway.
My suggestion with NodeRed is to remove only the automation from the device. Let ESPHome read sensors and control things when told to and allow NodeRed/HA to control when to do things based on those sensors. Minimizes code and means you can edit parameters without re-programming it each time you want to change it.
With regards to this project I refer to the section that says when temperature is above X turn fan on, and when below X turn fan off. Wouldn’t it be good to be able to edit those temperature limits from the same place you can monitor the fan from? Tis merely a suggestion. Each to their own. My preference is to let the software built for automation do the automation.
Thanks again for your comment and to @Stu1811 for putting in the work to share their hard work 
Sharing what your using, a link to the project, your fan config, how your getting RPM, is it a sensor or is somehow calculated from somewhere else? Your question was a little confusing but that’s not unusual. Posting actual data, links, config, etc that’s how confusion is minimized and someone can actually help. No details then people are just going to take guesses or ask you for the information that should have been attached to the initial post.
I’m not picking on you or anything, I’m just saying for future reference. Adding one or a couple of these things, pictures, a config, a link and then a to the point description of the problem would have been more helpful than a 3 or 4 paragraph thing. All that extra stuff over multiple paragraphs, it makes it more confusing a lot of the time. I really mean no offense but, you put some time and a few minutes into that post and it’s obvious you meant well and you tried but, it’s all mostly not important, not useful and now confusing.
Would you be talking about a server rack ran controller with rpm sensor?
Thanks for this code, it’s just what i need, but…i’d like it to work with a dallas sensor instead. I’ve tried but just cannot get it to work. Would anyone be so kind as to post up the code, but for a dallas sensor instead of a dht ?
Thank you in advance
Lee
Go look at the documentation , it explains how to do it. You gotta be a big boy and make an effort.
I already done it. I’m sorry but I forgot to post up to say so.
Thank you so much for your reply, it means the world to me
This is ace.
Am going to do this.
I have three NF-F12 Industrial 3000RPM fans.
If I were to extend this circuit for controlling the three fans individually, I assume:
- Add PWM & RPM for Fan 2 to D3 and D4
- Add PWM & RPM for Fan 3 to D5 and D6
- Would need 2 extra 10k Resistors
- would keep the single DHT11
Rather old thread but I still like to add, that based on what I read here and elsewhere I also did my fan controller to upgrade my deye inverter (remove the noise). You can find my code here: GitHub - sker65/esphome-fan-controller: Yet another esphome based fan controller. Can be controlled either manually or by temperature sensor.
From my point of view the code is cleaner (simple linear temperatur characteristics), simple switch between manual and temp controlled, optional MOSFET to turn the fans off. See some more comments on the github
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Just clarifying it a little bit about what @fr8tra1n said about the 12V:
The OP said he was using a 10KΩ resistor from the 12V to the fan tachometer pin. This pin is also connected to the ESP8266, which he assumed, correctly, won’t survive to be exposed to 12V very long.
Quick clarification: the tachometer is not “sending pulses”. The line is always UP (12V), and the tachometer connects it to ground (GND) 2 times per revolution. Yeah, it’s “sending pulses” in the sense that the line is always at 12V (pulled up by the pull-up 10KΩ resistor) and those “pulses” are 0V (GND).
The tachometer may not work correctly with a lower voltage, let’s say, 3.3V, because, as the OP said before, the RPM readings were not accurate.
I’ve seen people trying to use a voltage divider (other 2 resistors) to bring the 12V line down to 3.3V, a voltage that the ESP8266 can stand, before reaching the ESP8266 pin. I didn’t test it yet but, in principle, it should work. These voltage dividers can be configured in many ways and there are many calculators on the web that you can use for helping with that. For example:
Voltage Divider Conversion Calculator | DigiKey
You can use, let’s say, a 27KΩ resistor for R1 and a 10KΩ resistor for R2, bringing the 12V input to 3.2V.
The formula is simple:
Vin / (R1 + R2) * R2 or, in our case, 12V / (27KΩ + 10KΩ) * 10KΩ which gives us 3.24V
Notice that Ohm’s Law (I = V / R) units are still obeyed in this formula. So, when we divide V / (R1 + R2), we have the current (I). But then we multiply it by R2, and I * R = V, so having our result in volts (V) is correct.
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