# Gauss meters



## GoodwrenchIntim (Feb 22, 2005)

what kind of demand would there be for a simple gauss meter??
you would need to supply your own 9v battery an volt meter to get a reading, then compare it to a chart i'm making in excel for true gauss(each would have a custom chart as measurements will vary slightly from the voltage regulator), will work up to 1000 gauss. Would be around $25 for it 

Kevin


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## Ligier Runner (Nov 29, 2004)

Sounds interesting and the price seems fair considering the work that is going into it. I've always wanted a meter but the price is what keeps me out of the game. I can't justify spending big bucks when I'm only going to use something like that on occasion.


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## neorules (Oct 20, 2006)

Good idea, but the 1000 gauss range is too small. Most magnets even ceramic are well over 1000 gauss. Would need to be higher range to be realistic.


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## GoodwrenchIntim (Feb 22, 2005)

most stock mag are under 1000 gauss( at least tycos are), that is what this will be used for( stock mags). for higher gauss mags you can make a gig to hold the mags farther away an get a reading for matching purposes but not true gauss this way


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## Dranoel Dragon (Oct 9, 2007)

GoodwrenchIntim said:


> most stock mag are under 1000 gauss( at least tycos are), that is what this will be used for( stock mags). for higher gauss mags you can make a gig to hold the mags farther away an get a reading for matching purposes but not true gauss this way


The Aurora mags are way under 1000 gauss. Anything modern may be under 1000 but just barely. Even JL/AW mags are at 900. Most ceramic traction magnets go well over 1000. (including Tyco)

http://www.hoslotcarracing.com/index.html (look in the Magnets section for a chart.

I'm fairly sure there's a way to wire a resistor into the circuit that would cut the power output in half and double your gauss range.


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## GoodwrenchIntim (Feb 22, 2005)

Dranoel Dragon said:


> The Aurora mags are way under 1000 gauss. Anything modern may be under 1000 but just barely. Even JL/AW mags are at 900. Most ceramic traction magnets go well over 1000. (including Tyco)
> 
> http://www.hoslotcarracing.com/index.html (look in the Magnets section for a chart.
> 
> I'm fairly sure there's a way to wire a resistor into the circuit that would cut the power output in half and double your gauss range.


I wanted this basically for motor mags for t-jet/ afx. tyco an similar that use stock mags. My readings are a little lower then what he has, but all gauss meters will read different, Older tyco traction mags can be gaussed by this but I tested a new one from the mattel chassis an it pegged it so those wouldn't be able to be gaussed without a jig or resistor added, but Im more worried about motor mags then traction

As for the resistor, there is a way to do that by adding a couple resistors an a switch(may increase price, an that's what i am trying to stay away from). Ill have to research that more to find out how

I do have plans for a more advanced gauss meter but I have not got it to work yet. With it what your meter would say is what the gauss would be. with the one im doing now you would have to put the meter reading in an excel chart to get true gauss or I could do a chart for each one that you just look an see what the meter says an match it to the chart for gauss

This is just in the works an nothing definate. Im trying to make cheap good working things to keep the hobby growing an not dieing. If I could find a higher value Halls effect device this one i'm building now would do most mags, but the higher value ones are a lot more expensive


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## roffutt (Jun 30, 2006)

What is the milivolt per gauss rating of the hall sensor you are using?


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## GoodwrenchIntim (Feb 22, 2005)

2.5 milivolts


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## Tjettom (Jan 1, 2008)

I had used those devices only to find I much prefer using a cheap Harbor Freight digital scale much better. By attaching a metal slug to the scale plate and arranging the magnet on a fixture directly above and inline on center with the metal slug (and center of scale),I simply measure the pull on the metal slug. Of course the digital scale reading will show a - (negative) weight (pull)......

Hope this may help and work for you too....Should cost less than $20.00.......:thumbsup:

Tjettom Baker


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## roffutt (Jun 30, 2006)

Allegro A1302EUA-T

- Sensitivity 1.3mV/G

This seller on Ebay has them for $1.40 each.. shipped from hong kong, so it took about 4 weeks to arrive.. but can't beat the price.

http://cgi.ebay.com/A1302-Linear-Hall-Effect-Sensors-Magnetic-sensor_W0QQitemZ370113638834QQihZ024QQcategoryZ36332QQssPageNameZWD1VQQrdZ1QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247

I have a brp magnet matcher that I believe uses a 1.0 mV/G sensor. 

I always wished there was a more consistent process to use.. I found it very difficult to find and pin-point area on the magnet with the highest value. Especially with curved motor magnets. A lot of patience, which I've not been known to have any of.  I first upgraded to a good bench top multimeter that had options to hold the max/min values, which helped make the process a bit better. Recently I scored a top of the line gauss meter that has functions to hold the max value. I'm still not convinced that finding the strongest (peak value) is always the best... because another magnet may have a lower peak value but if you averaged the gauss of entire surface of the magnet, it would be higher.. just my theory, still working on trying to prove it.

-Robbie


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## roffutt (Jun 30, 2006)

Tjettom said:


> I had used those devices only to find I much prefer using a cheap Harbor Freight digital scale much better. By attaching a metal slug to the scale plate and arranging the magnet on a fixture directly above and inline on center with the metal slug (and center of scale),I simply measure the pull on the metal slug. Of course the digital scale reading will show a - (negative) weight (pull)......
> 
> Hope this may help and work for you too....Should cost less than $20.00.......:thumbsup:
> 
> Tjettom Baker


Tom, 

Sounds cool.. I'd love to see pictures if you have any to share. Same principle used by magnet marshal devices.

Do you find it easy to differentiate between a average magnet and good one? 

Thanks,
Robbie


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## GoodwrenchIntim (Feb 22, 2005)

Tjettom said:


> I had used those devices only to find I much prefer using a cheap Harbor Freight digital scale much better. By attaching a metal slug to the scale plate and arranging the magnet on a fixture directly above and inline on center with the metal slug (and center of scale),I simply measure the pull on the metal slug. Of course the digital scale reading will show a - (negative) weight (pull)......
> 
> Hope this may help and work for you too....Should cost less than $20.00.......:thumbsup:
> 
> Tjettom Baker


Ive did this as well, works good for matching magnet strength. A gauss meter will show the strongest edges though



roffutt said:


> Allegro A1302EUA-T
> 
> - Sensitivity 1.3mV/G
> 
> ...


I may have to look at those. I got all these I have now as Samples to see what was gonna work best. Ill have to see if I can get some samples of those from my sample sites

I used a brass tube an notched it for my halls effect sensor this way you can get the mag in the same spot each time

let me know about what you find out about avg, gauss compared to edge gauss would be interesting to know

Thanks
Kevin


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## bearsox (Apr 22, 2006)

neorules said:


> Good idea, but the 1000 gauss range is too small. Most magnets even ceramic are well over 1000 gauss. Would need to be higher range to be realistic.


Change the distance between magnet and hall effect device since all you would be changing is flux line stretch and problem solved. Personally i have 2 devices but really a compass , ruler and credit card work as well as most matchers do ! Put compass pointing due north. Ruler extending from south marker . Cut magnet shaped notch in card blank . Place magnet in notch and slide forward till compass needle moves . Mark spot and swap in more magnets until same result ! Voila. 

later , Dennis :wave:


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## neorules (Oct 20, 2006)

TjetTom--- I think I have the same scale from harbor freight. It reads up to 1000 grams positive or negative. I have been reading car down force through the plastic plate that covers the scale. Seems to give consistent negative lift readings so far. P.S drill a hole through plastic plate to reset switch on scale.


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## resinmonger (Mar 5, 2008)

Does anyone still use 0.177 steel BBs?


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## blubyu (May 4, 2008)

Yeah, when I feel like counting.....


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## majdave79 (May 31, 2006)

*Magnet reader*

Kevin,

I mounted my HE device in the center (arm) hole of an old chassis. I just place the magnets in their slots (one at a time of course) and get a consistent distance.

Personally, I am not convinced getting a Gauss reading is all that critical. You are really just trying to find your strongest magnets, and trying to match the strength of N-S magnets. Any reading device (voltmeter, force guage, digital scale) will do the trick.

Going to try to attach a photo of my latest MM.

Dave


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## noddaz (Aug 6, 1999)

*but, but, but*



majdave79 said:


> Kevin,
> 
> I mounted my HE device in the center (arm) hole of an old chassis. I just place the magnets in their slots (one at a time of course) and get a consistent distance.
> 
> ...


No, in serious building it is not just the gauss reading...
It can also be just where the strong point is on each magnet.
Let's say that the strongest spot on a N magnet is a bit offset to the right.
If you find a S magnet of the same strength with it's strong spot offset to the left it can have the effect of advancing (or retarding) the timing of the armature. Also magnets that are stong on the top (or bottom) can be flipped to line up the strong spot with the armature stacks..... Or to have a little more pull on the rails...
This is something you cannot do with BBs unfortunatly.
Do I do this? No, I don't own a gauss meter because I do not want to get that involved with my little cars... The science is cool, but for me some of the fun goes out of it. Of course if I manage to find a gauss meter somewhere really cheap that may change... :lol:

Scott


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## GoodwrenchIntim (Feb 22, 2005)

As Scott said , This isn't just for gauss but to find the strongest points to. Mountng in the chassis is a good idea, but then you are limited to just matching mags an not finding the strongest points


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