# Tachometer EC Fan

**URL:** https://discourse.nodered.org/t/tachometer-ec-fan/6475
**Category:** General
**Created:** [6 January 2019 20:35 UTC](https://discourse.nodered.org/t/tachometer-ec-fan/6475 "2019-01-06T20:35:13Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![dakure](https://avatars.discourse-cdn.com/v4/letter/d/59ef9b/32.png) [@dakure](https://discourse.nodered.org/u/dakure)
#### Post date: [6 January 2019 20:35 UTC](https://discourse.nodered.org/t/tachometer-ec-fan/6475/1 "2019-01-06T20:35:13Z")

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Hi,  
I want to read the rpm s from a EC (Electronically Commutated) fan.  
I did it with a python script but I was wondering the best way to do it in NodeRed.  
I don t realise how to get the pulses for minute using the raspberry nodes... My plan is to control 4 fan with one raspberry.  
The tachometer info says : Tach output: open collector, 1 pulse per revolution, electrically isolated.

Thank you and happy new year everybody!

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### Author: ![simonsparks](https://avatars.discourse-cdn.com/v4/letter/s/dc4da7/32.png) [@simonsparks](https://discourse.nodered.org/u/simonsparks)
#### Post date: [9 December 2021 13:11 UTC](https://discourse.nodered.org/t/tachometer-ec-fan/6475/2 "2021-12-09T13:11:42Z")

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Did you ever figure out how to achieve this?

I would like to also control 4 x EC Fans from a Raspberry Pi 4B and also read the Tachometer Open Collector Signal and display it in Node RED using a Gauge on the UI.