On Sunday 22 August 2021 17:04:06 Gene Heskett wrote: > On Sunday 22 August 2021 12:46:14 Polyna-Maude Racicot-Summerside wrote: > > On 2021-08-22 10:02 a.m., Emanuel Berg wrote: > > > tomas wrote: > > >> I disagree. The thing poses [1] as a DC motor (2 pins power, > > >> one tacho). I don't think you get too much control over RPM > > > > > > That's what you get with the 4th wire/pin? A sensor to > > > read RPM? > > > > Opposite > > 3 wire = 2 wire to drive motor + 1 wire to get speed > > 4 wire = 2 wire to drive, 1 to get speed, 1 to modify speed > > I as a CET, am totally unimpressed with the miss-information being > thrown about in this thread. A total lack of how its actually done in > real hardware. > > 1. Any si diode, passing a few microamps of fwd current, is in fact an > excellent, does not need to be calibrated, thermometer capable of 1 > degree C accuracy. There are several million candidates buried in > todays cpu's. > > 2, even a 2 wire fan can be controlled by using this voltage to > determine the on time of a small transistor. Often down to 1% speed at > room tmps, so other than the cost of the time at die bondout time, its > free. The 1% minimum is actually used to help distribute the motors > lubricant. > > 3, boiled down, the temp measured by this diode can be scaled to > control the fan to maintain the device being monitored at a fixed > maximum temp, and its done on 2 or 3 of the gates on the cpu die > intended to be used to replace a bad gate in you cpu. Intelligently > done at test and bondout time, it might add 10 seconds to the time > needed to verify the rest of the chip. > > > > "What you can't measure, you can't control" > > Better, if you can measure it, you can control a 2 wite motor. > And I knew I couldn't get by without a typu. s/b wire. In fact, if a motor has 3 wires, there is a good chance its a tacho wire, used ONLY to tell /you/ how fast its running.
> Cheers, Gene Heskett Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene>
