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     English: Magnets, love 'm, hate 'm, measure them
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tamar





Posts: 772
Registered: 5-1-1989
Location: Gouda
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Mood: A new beginning ;)
posted on 31-8-2018 at 11:35 Reply With Quote
Magnets, love 'm, hate 'm, measure them



When quotes like "Real men don't use magnets" start to appear in forum post...
... you know you're in for an other discussion round on the "big divide in 1/32 scale slotracing". Magnets in slot cars have always been a very opinionated topic. Some love em, some hate em...But if your track has "metallic" braids..you better start measuring them. As the handling of even the most "mag-less" slot cars will be influenced by the amount of "downforce" their motor magnets provide.


Marshalling Magnets

Which is why, at the turn off the century, many clubs started building their own magnet measuring devices. These devices were usually constructed around a regular scale with a metal strip suspended above the scale to simulate the track braids. Measurements required two steps, the first was weighing the car placed on its side on top of the scale, the second with the car placed on its wheels over the metal strip.
The increase in weight (due to the (motor) magnets pull on the metal strips) would be used as a value (in gr) to measure the amount of "down force". Did each gram of measured downforce really equall a gram of lead? Well it did not matter, as long as one used the same scale for all measurements it was a very exact way to compare magnet "downforce" between different cars.

To the right you'll see an image of one of the then commerially available magnet downforce measuring devices .The since long out of production, but still much saught after Magnet Marshall (image courtesy of Professor Motor)


Tesla Meter app
So fast forward two decades into the world of mobile devices and apps. Its really amazing how much computing power is stuffed into our favorite talkies. Some time ago I stumbled onto an app called Tesla Meter (available for both IOS and Android) This app takes advantage of the built in magnetometer in your mobile device, allows you to monitor the strength of magnetic field all around.
Cut a slot in the bottom side of an old display case, place your car on top andslide your mobile device underneath....and voila...you've got yourself a modern Magnet Marshall.


The app measures the magnetic field generated by your car and displays it in MicroTesla's (µT)
100 Microtesla (µT) = 1 Gauss (G) Again as with the original Magnet Marshall how this translates into grams (gr) isn't really important, what is important is the amount of "magnetism" when comparing different cars or car set-ups.

Replicable measurements.
Any true, professional measuring device would need a calibration tool for its measurements to be..well..calibrated so it can be replicated at other locations. Which off coarse my "high tec" tool utterly lacks. But as long as everybody would use the same smarthone (or at least with the same thickness) and the same old Slot.it display.....the measurements should be replicable world wide ;)





Note: I'm considering of setting up a "conversion" service. Send me your display an by using the latest technology I will transform it into a state of the art Magnetic field measuring device. Conversion costs would start at €100 ex postage (Smartphone and Scalectrix AMG GT3 not included) Custom liveries on demand (as long as they're black) ;)




With kind regards
Tamar
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