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Use magnets to nullify magnetic field ?

Use magnets to nullify magnetic field ?

(OP)
This is not a professional question:

I used 3 rare earth magnets to install a steel bracket in my track vehicle to support a GPS track timing system. the 3 magnets are fastened to a horizontal plastic surface with Gorilla brand double sided mounting tape. The wide steel bracket is L shaped providing a vertical surface to mount the timing device. The timing device itself has 2 rare earth magnets imbedded in the back for fastening to a steel vertical surface.

Question: The steel bracket is mildly magnetized from the 3 magnets that hold it in the vehicle. Would adding magnets to the steel bracket in the correct location and polarity, partially nullify the magnetic field around the steel bracket that may affect the timing system ?

RE: Use magnets to nullify magnetic field ?

I would expect that a DC (steady state) field has no effect on the unit.
It is receiving radio timing transmissions to do its job.
For maximum holding though there are two things to address.
1. large contact area so that it can't tip
2. the mounted magnets should align, and be in opposite polarity to the ones on the bracket

It would even be better if you had mounted the magnets to a piece of steel. You only have holding force when the magnetic circuit is closed.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Use magnets to nullify magnetic field ?

(OP)
Thank You for your reply. The 3 rare earth magnets provide a very durable mount to the vehicle's plastic dashboard surface. I had to add a mechanical interlock to prevent the steel plate from sliding on the magnet surfaces. The device works normally. I am happy the hear that a constant magenetic state (dc) should not interfere with RF reception.

Thank You again

RE: Use magnets to nullify magnetic field ?

No worries in this application, especially in your design: the magnetic flux from your RE Magnets will be shunt away by the steel, your GPS will actually not "see" a field.
Even with a magnetic filed pass through your GPS, you are probably still fine because GPS receives satellite signals.

Strictly speaking, however, a magnet could affect a GPS if it has a built-in hard diver and memory card. Also, a very strong magnetic field could disturb electrons to affect a GPS.

RE: Use magnets to nullify magnetic field ?

(OP)
Thanks for your input. The system in question doesn't have a convention hard drive, but of course has flash memory and its programs on a programmable chip. But everything is working.

RE: Use magnets to nullify magnetic field ?

It really depends. If your memory card functions with magnetized particles (FYI: people are trying to make one particle one signal, when nanoparticles are aligned, you can imagine how high the areal density it will be!), obviously, a magnet will affect. If the memory card is silicon-based (most probably), the effect from a magnet is very limited. Even so, if the magnet is strong enough, and when the GPS is loaded, unloaded...it "sees" a changing magnetic field, which could damage/decrease some of memory bits.

RE: Use magnets to nullify magnetic field ?

(OP)
OK, The manufacturer has two 3/4" diameter RE magnets built into the back of this device. Am I correct to believe that if these magnets do not adversely affect the unit, the similar magnets I have for mounting a bracket to the vehicle are will also have no adverse affect ?

RE: Use magnets to nullify magnetic field ?

Classical magnetic memories like magnetic bubble memories from TI are basically non-existent. Other memories, like the so-called "ferroelectric" memories are not actually magnetically based; the "ferro" refers to the hysteresis in the charge vs. voltage curve.

Most electronic circuits can withstand magnetic fields that are essentially impossible for ordinary people to generate; i.e., they require either a nuclear explosion or an EMP generator to cause disruption or damage.

TTFN
I can do absolutely anything. I'm an expert!
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers

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