Clear Min/Max values

[dkpodder]

Hi.

When spooling up, my UniSens E detects some crazy high RPM.

How do I clear min/max values on a switch, preferably a sequenze started by amp draw?

[Groucho_]

Originally Posted by dkpodder

Hi.

When spooling up, my UniSens E detects some crazy high RPM.

How do I clear min/max values on a switch, preferably a sequenze started by amp draw?

Try connecting the RPM sensor wire to another of the three motor/esc cables.

It may fix it instantly.

[W.W.]

Maybe the Unisens detects the pwm-switching as rotation signals. I can observe this in my T-Rex 250 too. When Spooling up there is first a raise in RPM, then it Drops and raises again. And no, there is no rpm drop in real.

regards Wolfgang

[dkpodder]

Exactly same issue here, T-rex 250, RPM raising, lowering, raising, settling.

Could try switching sensor lead connection, just can't see why it should fix the problem.

[W.W.]

I can't see, why switching the sensor connection should fix it too!

I think, the pwm frequency comes in the same range as the field changing frequencies could be in. In my opinion ist a missinterpretation, but i could live with this, because in flight the rpm data is correct. Compared to helitach app there is a only neglectable difference.

best regards

Wolfgang

[Groucho_]

Originally Posted by dkpodder

Could try switching sensor lead connection, just can't see why it should fix the problem.

Originally Posted by W.W.

I can't see, why switching the sensor connection should fix it too!

Neither can I, but it fixed it for me when I had this issue with a Unisens.

[Coco66]

Logic says that something "flows" differently in the different wires, otherwise you could not change the motor direction by swapping two wires...

[W.W.]

@Coco66:

Thas just the signal timing between the wires

1 - 2 - 3 - 1 - 2 - 3
or
1 - 3 - 2 - 1 - 3 - 2

So swapping two of the three wires changes the direction. But when you only watch one wire, you only see on/off (or maybe +/0/-). The time between two "on/+"-Events is interpreted as on field change. So number of field changes per second divided by the number of poles gives the rpm. This is the same on all wires at the same rotation speed only detected at a slightly different time.

But in the spin up the esc reduces the effective voltage or current using pcm. Maybe it starts always with the same wire and this influences the rpm measurement by the Unisens.

I have this double ramp up in telemetry with both of my helicopters. So I think, ist not dependend of the wire (or ist simply by random the same wire I took).

[Coco66]

I actually now remember I used to have that problem with the Spektrum sensor, never experienced it after moving to the Hyperion sensors (on three helis).

[Groucho_]

Originally Posted by Coco66

I actually now remember I used to have that problem with the Spektrum sensor, never experienced it after moving to the Hyperion sensors (on three helis).

Which reminds me... What happened to those Hyperion sensors?

I haven't seen them in stock for a couple of years now.

[prototype3a]

FWIW, the hobbywing rpm sensors are better. I know some escs (Castle, maybe others) pulse the motor in a way that confuses the Hyperion sensor.

[Groucho_]

Originally Posted by prototype3a

FWIW, the hobbywing rpm sensors are better. I know some escs (Castle, maybe others) pulse the motor in a way that confuses the Hyperion sensor.

The good thing about the hyperion sensor, apart from it's tiny size, was the need for just a single cable to be attached between the motor and esc.

The hobby wing uses two, and I believe I had a spektrum sensor a long time ago that also used two.