You are about 99.999% likely to be right. 😀 I haven't looked at that third lead
yet with a 'scope as I told John I would by email yesterday, but for my
application I can use an old style thermostat to power both fan and pelletier
devices on and off. I don't think I have to care about the .0001% chance this
is some outlier design.I was mostly ignorant about these fans and how many
flavors there are, not thinking right about the high resistance, not wanting to
blow the thing up, conflicted about the third wire being tach or control,
etc.As I shared with you, the last "weird motor" I encountered was from a
server disc drive with just three windings in series.I didn't include yesterday
that I learned in the hardest way imaginable how difficult it is to control
such a motor without arranging to sense the back EMF the motor design requires.
The summary is that it is a fool's errand. There are no Hall effect sensor(s)
in that motor, in case somebody is tempted to 'splain this. I spent an
embarrassing number of days on that, against the hard stop in Edison mode and
wishing I'd spent five minutes in Tesla mode earlier. By the time I realized I
had to use a controller my time budget had been exhausted five fold and I never
confirmed the Phillip's chip was the right part. Bought a stepper motor and got
on with my life. 😀Thanks again, everybody. This was fun.PeteSent by my phone
with an editing mind of its own
-------- Original message --------From: Brian via TriEmbed
<[email protected]> Date: 2/3/21 10:42 AM (GMT-05:00) To:
[email protected] Subject: Re: [TriEmbed] laptop fan motor control question
On 2/2/21 5:14 PM, Pete Soper via TriEmbed wrote:> Thanks, guys. The
connections were red for positive, blue for ground and > brown for what I
assume is the PWM input. That third wire is almost certainly[1] a tachometer
OUTPUT, not an input. It's there so that the motherboard can monitor fan
speed. Modulating the speed would be accomplished by one of the several methods
that other folks've mentioned.-B[1] - unless, ya know, it isn't. :)
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