# [EVDL] Zolox RPM sensor flat-lining



## EVDL List (Jul 27, 2007)

Hi All,

I recently installed a Zolox speed sensor on the tailshaft of a Warp9.

Installation pictures:

http://civic-ev.blogspot.com/2008/12/mounting-zolox-sensor.html

I have a 2.2K pullup resistor on the output and I'm observing the
pulses with an oscilloscope. When I press on the accelerator,
the pulses tend to flat-line (i.e. pull the output to ground). When
I let up on the accelerator, the pulses correctly show the RPM
of the tailshaft.

I'm guessing that the magnetic field from the motor during acceleration
is activating the hall-effect sensor in the Zolox unit and pulling down
the output. This concerns me because that means I can't use the
sensor for over-rev protection during acceleration, which can be an
issue when starting in first gear.

Has anyone seen this issue before? Any suggestions on how to
fix it? Thanks for your input!

Cheers,
Tim
http://civic-ev.blogspot.com




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## EVDL List (Jul 27, 2007)

So? what does the manufacturer say is wrong with your installation? (What 
does changing the pull-up to 1K or 500 ohms do?) It does sound as if the shaft 
is becoming magnetized during motor run and saturates the sensor. If no more 
"Elegant" solution presents itself, add a 5 or 10 mm nonmetallic spacer to 
the end of the motor shaft and the magnet for the sensor goes on the end with a 
nonmagnetic screw. and a spacer ring goes under the sensor mounting bolts to 
hold it in the right location 5 or 10 mm away from the motor end too. The 
space will greatly reduce the strength of the magnetic field at the sensor. 
Alternatively, trade it in for a photo operated sensor which will be oblivious 
to the magnetic field. And Good-Luck, tell us what worked!


In a message dated 1/8/2009 1:55:05 A.M. Eastern Standard Time, 
[email protected] writes:

Hi All,

I recently installed a Zolox speed sensor on the tail shaft of a Warp9.

Installation pictures:

http://civic-ev.blogspot.com/2008/12/mounting-zolox-sensor.html

I have a 2.2K pullup resistor on the output and I'm observing the
pulses with an oscilloscope. When I press on the accelerator,
the pulses tend to flat-line (i.e. pull the output to ground). When
I let up on the accelerator, the pulses correctly show the RPM
of the tailshaft.

I'm guessing that the magnetic field from the motor during acceleration
is activating the hall-effect sensor in the Zolox unit and pulling down
the output. This concerns me because that means I can't use the
sensor for over-rev protection during acceleration, which can be an
issue when starting in first gear.

Has anyone seen this issue before? Any suggestions on how to
fix it? Thanks for your input!

Cheers,
Tim
http://civic-ev.blogspot.com




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## EVDL List (Jul 27, 2007)

I just tried mounting the zolox speed sensor (that I bought from evsource)
today to the tail shaft of my WarP 9 motor. I also bought the standoff that
evsource sells, so the sensor mounts perfectly. But it's the magnet that's
giving me trouble: apparently the screw that came with the magnet is too
small to screw into the existing threads on the tail shaft. Anybody else
have this problem? I'm thinking I could try a larger screw, but I'm afraid
that would require drilling out the hole in the middle of the magnet...
suggestions? thanks!

Philip Rash




> Tim Kutscha <[email protected]> wrote:
> 
> > Hi All,
> >
> ...


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## EVDL List (Jul 27, 2007)

Hello Philip,

Install a heli-coil into the threads of the pilot shaft. This is a thread 
reducer device. You can get them at some hardware stores or at a machine 
shop. Have the machinist show you how to install it. It takes a special 
installation tool that comes with a kit.

Roland


----- Original Message ----- 
From: "Philip Rash" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, June 20, 2009 1:51 PM
Subject: Re: [EVDL] Zolox RPM sensor flat-lining


> I just tried mounting the zolox speed sensor (that I bought from evsource)
> today to the tail shaft of my WarP 9 motor. I also bought the standoff 
> that
> evsource sells, so the sensor mounts perfectly. But it's the magnet that's
> giving me trouble: apparently the screw that came with the magnet is too
> small to screw into the existing threads on the tail shaft. Anybody else
> have this problem? I'm thinking I could try a larger screw, but I'm afraid
> that would require drilling out the hole in the middle of the magnet...
> suggestions? thanks!
>
> Philip Rash
>
>
>


> Tim Kutscha <[email protected]> wrote:
> >
> > > Hi All,
> > >
> ...


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## EVDL List (Jul 27, 2007)

Thanks for the suggestion, Roland; I'll check into the heli-coil approach! I
suppose I'll need to know what size/ thread the pilot shaft has... does
anybody happen to know, or can suggest a way to measure it? Thanks again for
all the help,

Philip




> Roland Wiench <[email protected]> wrote:
> 
> > Hello Philip,
> >
> ...


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## EVDL List (Jul 27, 2007)

Hello Philip,

The pilot shaft is tap for a 1/4-20 thread size. Just try a 1/4 inch bolt 
with 20 threads per inch bolt size.

Roland


----- Original Message ----- 
From: "Philip Rash" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, June 20, 2009 3:38 PM
Subject: Re: [EVDL] Zolox RPM sensor flat-lining


> Thanks for the suggestion, Roland; I'll check into the heli-coil approach! 
> I
> suppose I'll need to know what size/ thread the pilot shaft has... does
> anybody happen to know, or can suggest a way to measure it? Thanks again 
> for
> all the help,
>
> Philip
>
>
>


> Roland Wiench <[email protected]> wrote:
> >
> > > Hello Philip,
> > >
> ...


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## EVDL List (Jul 27, 2007)

awesome; will try that... thanks again!

Philip




> Roland Wiench <[email protected]> wrote:
> 
> > Hello Philip,
> >
> ...


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## EVDL List (Jul 27, 2007)

> Roland Wiench <[email protected]> wrote:
> "The pilot shaft is tap for a 1/4-20 thread size.
> Just try a 1/4 inch bolt with 20 threads per inch bolt size."
> 
> ...


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## EVDL List (Jul 27, 2007)

>>>so for under $10, I save many trips....

(The other few dollars goes toward the Sharpie
pen to write the bolt spec on the bolt.)

BTW, it's nice to have a nut to test a bolt,
but you can also test a bolt against a bolt.
if it is the same size and tpi/tpmm, it will
mesh perfectly.

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## EVDL List (Jul 27, 2007)

Philip,



> Philip Rash <[email protected]> wrote:
> 
> > I just tried mounting the zolox speed sensor (that I bought from evsource)
> > today to the tail shaft of my WarP 9 motor. I also bought the standoff that
> ...


----------



## EVDL List (Jul 27, 2007)

> TimK wrote:
> >
> > Hi All,
> >
> ...


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## EVDL List (Jul 27, 2007)

It is best to make the mounting bracket for any magnet sensor and a magnet 
device that attaches to a motor out of aluminum. I have 4 layers of 
aluminum 1/8 x 1 inch bar that is bolt to the face of the motor. The 
magnets that Otmar sent me are 0.25 inch diameter place on a solid steel 
coupler that is 2 inches in diameter place which 4 of them are place 90 
degrees apart.

This makes the spacing equal to 3.14 x 2 = 6.28 minus the four 0.23 inch 
magnets or 6.28 - 1 inch = 5.28 inches. The space between the magnets is 
5.28/4 = 1.32 inches. The maximum calculated space that these magnets can 
be space is about 1.50 inches. If you have a larger space between the 
magnets then this dimension, than you would have to stack two magnets 
together to get below this spacing.

This spacing of one magnet space every 90 degrees with a 1.32 inch space, 
works good so far up to 5500 rpm, which is the maximum I set my motor for.

Another thing, that most motor installations is setting on rubber engine and 
transmission mounts like my motor is. There is a lot of motor magnetic flux 
that is conducted by the fields to the motor case and may have some type of 
capacitance reaction to near by devices and the body of the EV.

The sensor cable that goes to the sensor unit and to the motor controller, 
is double shield. The aluminum tape shield around each conductors are left 
floating, meaning they do not attach to any vehicle chassis ground. The 
other shield at the sensor unit is only grounded to the aluminum bracket 
that holds the speed sensor.

I also have every devices install in seal cast aluminum boxes, that each one 
is cable grounded to a ground counterpoise system.

The tack wire that goes to the motor controller is also double shield and 
only the outer shield is ground to the tack ground.

If you still have a problem with noise, it may help to install a large 
ground strap from the motor to a 12 volt ground point that is counterpoise 
connected with a large conductor to the 12 volt source. I do not relied on 
any sheet metal of the EV to carry the 12 volt negative return circuit.

When I install this grounding system in this way, I do not get any AM radio 
noise, except only when I first start up the motor and it goes way when I 
get up to about 1 mph.

Roland


----- Original Message ----- 
From: "Otmar" <[email protected]>
To: <[email protected]>
Sent: Sunday, June 21, 2009 9:40 AM
Subject: Re: [EVDL] Zolox RPM sensor flat-lining


>
>


> > TimK wrote:
> > >
> > > Hi All,
> > >
> ...


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