Magnetics

[(unknown)]

Is there a way to make a device to hear magnetic fields/flux through a simple amplified circuit? My goal is to produce a varying tone for different flux strengh.

Anybody have any suggestions??? Please help!!

[bob golding]

hi, if you look up linear hall effect devices first. find the output they give then interface that to a voltage to frequency converter chip and use the output of that to drive an amplifier. just  to give you somewhere to start. there are other ways to do it but that should get the ball rolling.

bob golding

[stop4stuff]

lol...

i was searching just yesterday for a homemade gauss meter,

here's a circuit using readily available parts that gives a varying DC output based upon the magnetic field strength

http://my.execpc.com/~rhoadley/magmeter.htm

so linking from that circuit to Bob Golding's method shouldn't be too difficult

from what i can figure a hall effect sensor with a rating of 2500 gauss should be ample enough for most magnetic fields inc NdFeB (neo's)... someone please correct me if i'm wrong (because i'd like to make something similar too)

[Flux]

2500 gauss is too low to be much use with neos. Their Br is about 1.2T (12000 gauss)

Even in air gap dual rotor machines neos generally operate at about 0.6T.

2500 is probably usefull for dual rotor ceramics if you keep the gap large.

I have never found a sensibly priced Hall sensor that will handle neos.

Flux

[kitno455]

any way to shield the hall effect device so it wont saturate? like some steel screen wrapped around it, or stuck in a ball of steel wool?

allan

[(unknown)]

Beldon Sheilded cable works good, It has 2 insulated conductors and a bare ground, all three covered with a metal sheith

[(unknown)]

Thank you for the help. Although i have a gauss and tesla meter the link you provided is very helpful in finding polarity of field. It will work well with a buzzer type meter and db meter

[kitno455]

but can you get the shield off and put it around the hall effect device?

allan

[(unknown)]

Yes you can strip back the outer jacket and un-wrap the metallic shield. Unfolded it is about one and a half inches wide.  (its Belden cable not Beldon.)

[(unknown)]

Thank you for your help. I will try a converter chip method for this project. Tell me if you think this would work...using the schematic stop4stuff suggested could I not just replace the volt meter connections with a variable voltage hi/lo piezo type horn? Or do I still need a amp?