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GIRI Phone Based Speed Checker App

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#1 SlotsNZ

    Formula 1 Driver

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Posted 26 January 2019 - 10:03 AM

Someone shared this phone App on another forum.
The video compares it's result to using a Tamiya speed checking board with a Tamiya car.

A few talked about the theory, but no one had anything to say about having used it - so I have just done so
I was using the IOS version of the App on my 3 year old - and heavily abused i-Phone 6 plus. The mike on that may not be 100% as I have had it pulled apart twice to replace broken screens, and it has been dropped onto the cobbled streets of several cities.....

I have just run about 25 loose motors. About half being new of known spec., and half of which I had already written their RPM at 12V right braid positive on the can.
I also ran a couple of motors in pod with axle and gear, but no wheels, and about 10 in cars which have newish motors of known provenance - eg Slot.it MX15, V12/3 29k etc


- It is not a perfect tool, needs a bit of fiddling for each motor to ensure the mike is in the best position.
- Too much gear noise and the reading gets confused, flicking between what appears to be correct motor RPM, with a combination of motor and gear harmonics at around 2/3rds motor RPM.
- The odd noisy car is not measurable
- The odd very quiet motor is not measurable (accurately)

But in about 80% of cases I could say I was confident enough of the RPM figure given to use it - along with listening to the hum of the motor to known if it sounds smooth or has a few "hiccups" as it runs.
I mightn't trust my life to it, but if I had to sift through some motors I thought might need a flush, or to choose a motor, or find out what an unknown motor IS in RPM performance.
The two Flat-6 angle-winder in Slot.it pod (no wheels) I ran, were measurable - not much gear or bush noise
So I think it is a usable tool - and a lot faster than using my non contact tacho for a heap of motors.

It already told me I have a few motors that have worked hard, and need to come out of a car, try a flush, and then test again.
Of course none of these tools are telling us the power of a motor. For that we still need to rely on experience, or at least manufacturer and other data sources for basic motor use selection.
But if RPM is down for a known motor, you can pretty well assume torque is down at least proportionally, and probably more.

So I think it is a worthwhile tool with a place in our "toolkit"
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#2 dangermouse

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Posted 26 January 2019 - 11:02 AM

Tested it out with a couple of motors - it works.

Tested a motor with my DS rpm tool and then with the app.

results were comparable - 25.1 with DS and 25.3 with Giri

It probably works better with motor out of car but it does work with motor in the car. Also noticed that gear noise does effect it or maybe my Scalextric Javelin has a 60k motor in it Posted Image

I think it will be a handy tool for quick checking while trying to pick the 'best' motor and also for comparing motors between like cars.

It would also be quick and easy at racing to check a motor on a car that seems to be running 'hot'

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Edited by dangermouse, 26 January 2019 - 08:45 PM.

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