[Tesseract]

Originally Posted by PeterH

...But based on the settings and what I see, it looks like the pulse is only worth about 12 or 13 mV...

That waveform is not what I expected. If Kostov uses an inductive coil type sensor I would expect to see a pulse that goes positive (or negative) as a magnet approaches then negative (or positive) as the magnet recedes. The amplitude should also be a lot higher than 12mV, too.

I suspect something is hooked up wrong or that the scope is way out of whack. Use the scope's "calibration" signal to make sure a 1V/1kHz square wave actually reads as such.

[PeterH]

Originally Posted by Tesseract

Use the scope's "calibration" signal to make sure a 1V/1kHz square wave actually reads as such.

If I had a signal generator I'd be happy to do that.

Meanwhile, I've gotten further information that suggests the gap between the sensor and the shaft should be about .040 inches. I also spoke with the person that installed the tach sensor and he is fairly certain the gap is much greater than .040.

My task for the rest of the day is to put the EV on the lift and see if I can use a video inspection camera and put an eye on the sensor. Then I can decide if I need to pull the motor or not. Hoping not, but all indications are that I'll be pulling the motor some time VERY soon.

Just had a thought... bet I can rig up an arduino circuit quickly to play signal generator!

I'll update this thread later today after I have some more solid information.

Thanks,
Pete

[Tesseract]

Originally Posted by PeterH

If I had a signal generator I'd be happy to do that.

Take a closer look at your scope... just under the screen is a calibration signal

Pretty much all scopes have one.

[PeterH]

Using a simple program for an Arduino Mega board I've been able to demonstrate that my oscilloscope is accurately painting an image of the signal it is observing.

Which further supports the idea that there is something wrong with the tach sensor installed in my Kostov motor.

Aparently the entire end of the motor face was replaced with one that contained the sensor. That suggests that the gap for the sensor was factory set.

Pulling the entire drive line just to adjust or replace the sensor is, to say the least, hard to imagine. Especially when I consider how much work it was to fit the adapter onto the shaft of the motor in the first place. This adapter is a keyed press fit. That meant several hours of careful tapping with a wooden mallet to get it on.

So for the moment, I'll wait a couple of days to see if anyone from Kostov or whoever he got the sensor from responds to our questions BEFORE I consider spending several days pulling everything apart.

Pete

[PeterH]

Originally Posted by Tesseract

Take a closer look at your scope... just under the screen is a calibration signal

Pretty much all scopes have one.

Nuts, wish I'd have seen this before I dug out all that gear! Still, the more I use the scope, the more I learn about it so it was a useful exercise.

Thanks,
Pete

[Tesseract]

In another post you mention that the tach sensor on the motor has 3 wires... is that correct? If so, how do you have it wired? Weren't there any instructions or at least a description of the sensor with the motor?

[PeterH]

Originally Posted by Tesseract

In another post you mention that the tach sensor on the motor has 3 wires... is that correct? If so, how do you have it wired? Weren't there any instructions or at least a description of the sensor with the motor?

I'm not aware of any instructions that came with the assembly. Apparently when my local vendor ordered the upgrade from another stateside Kostov vendor, he got a complete endplate for the motor that contained the sensor. I was overseas at the time and didn't see him do the installation.

From the sensor, a Black wire is connected to the Tach terminal, a Brown wire is connected to the S12V terminal and then there is a third Blue wire connected to the SGND wire. Those wiring instructions came from my local vendor that installed the upgrade. I've heard the same instructions from another user who also was never able to get it to work with his Soliton. Hence my other post asking if anyone has ever gotten this to work.

I wonder if there is a need for a pull-up resistor somewhere in this... I'm hoping someone from Kostov will respond to a query my vendor sent today.

Thanks,
Pete

[Tesseract]

Originally Posted by PeterH

....From the sensor, a Black wire is connected to the Tach terminal, a Brown wire is connected to the S12V terminal and then there is a third Blue wire connected to the SGND wire. Those wiring instructions came from my local vendor that installed the upgrade. I've heard the same instructions from another user who also was never able to get it to work with his Soliton. Hence my other post asking if anyone has ever gotten this to work.

I wonder if there is a need for a pull-up resistor somewhere in this... I'm hoping someone from Kostov will respond to a query my vendor sent today.
...

*groan*

Yes, this type of sensor needs either a pullup or a pulldown resistor. Try 1k from TACH to S12V first and if that doesn't work then move over to SGND.

[TigerNut]

Originally Posted by Tesseract

*groan*

Yes, this type of sensor needs either a pullup or a pulldown resistor. Try 1k from TACH to S12V first and if that doesn't work then move over to SGND.

Check out page 12-14 of the datasheet at the bottom of this page... they have the right color wires, anyway (both the NPN and the PNP open-collector sensors, still have to try the resistor both ways)
http://kostov-motors.com/tractionmot...otorrpmsensor/

[PeterH]

Originally Posted by Tesseract

*groan*

Yes, this type of sensor needs either a pullup or a pulldown resistor. Try 1k from TACH to S12V first and if that doesn't work then move over to SGND.

Progress!

I added a 1K resister between TACH and S12V and now I get a nice square pulse worth about .6V. However, the trace appears below the zero reference. The sweep time in this image is set to 2 mS and the Volts/Div = .5.



This isn't near the required minimum of 4 volts. Would changing the resistance in the pull up resister change that?

Thanks,
Pete