Timeline for How to interpret the output of a 3-pin computer fan speed sensor?
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 16 at 16:36 | comment | added | Tank R. | Tach is an interrupt to gnd (a momentary high z state) when the field direction through the sensing region of the hall effect and coil control device (the thing with the 4 legs between the motor coils) changes in a specific direction. Assuming N to S, as the ring magnet polarity at the sensor face transitions from N to S it changes the coils and shortly interrupts the tach wire circuit to ground as if the wire wasnt connected to anything. S to N does nothing but change the coil polarity as normal. N to S, again interrupts. With 4 poles of the magnet, NSNS, thats 2 interrupts per rotation. | |
| S Sep 4, 2013 at 11:08 | history | suggested | Bruno Bronosky | CC BY-SA 3.0 |
what you describe is PFM not PWM
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| Sep 4, 2013 at 9:51 | comment | added | Bruno Bronosky | @NickT I proposed an edit. Let's see if it is accepted. | |
| Sep 4, 2013 at 9:50 | review | Suggested edits | |||
| S Sep 4, 2013 at 11:08 | |||||
| Dec 27, 2010 at 18:46 | comment | added | Nick T | it would be PFM (pulse frequency modulation) | |
| Dec 26, 2010 at 12:24 | comment | added | starblue | That's not PWM (pulse width modulation). | |
| Dec 26, 2010 at 2:15 | history | answered | Seidleroni | CC BY-SA 2.5 |