Electronics > Beginners

Mass flow sensor

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Gyro:
You need to read the article again.... Reminds him of one, yes. Mentions and describes real MAF sensors, yes. Terms it as one, no. He says it is a wind sensor, possibly capable of room occupancy sensing experiments.

ZeroResistance:

--- Quote from: Gyro on May 06, 2019, 11:38:07 am ---You need to read the article again.... Reminds him of one, yes. Mentions and describes real MAF sensors, yes. Terms it as one, no. He says it is a wind sensor, possibly capable of room occupancy sensing experiments.

--- End quote ---

They are using the constant temperature hot wire method, wouldn't the same principle be used for sensing Mass Air Flow ?

Having said that I have a schematic for their latest version attached.
I don't understand why they are taking an output from the bridge itself if they are maintaining the hot wire at a constant temp. that voltage would be constant wouldn't it? They should have taken the output from the feedback op-amp output.
I hope I'm reading the schematic correctly.



mikerj:

--- Quote from: ZeroResistance on May 12, 2019, 08:15:03 am ---I don't understand why they are taking an output from the bridge itself if they are maintaining the hot wire at a constant temp. that voltage would be constant wouldn't it? They should have taken the output from the feedback op-amp output.
I hope I'm reading the schematic correctly.

--- End quote ---

The higher the wind speed, the more power you have to dump into the sensor to maintain its temperature and therefore the higher the voltage across it.

Simon:

--- Quote from: mikerj on May 12, 2019, 10:12:08 am ---

The higher the wind speed, the more power you have to dump into the sensor to maintain its temperature and therefore the higher the voltage across it.


--- End quote ---

i think most comercial sensors use the current draw by the hot wire to maintain a stable temperature as the actual signal.

radiolistener:
https://hackaday.com/2017/07/26/measuring-air-flow-with-ultrasonic-sensors/

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