Possible Fix for EMI

[DizzyDigger]

I've always said I know just enough about EMC to be dangerous. Spent half a day on Thursday in a 3M chamber fixing a client's problem. That's enough for me for a while. Maybe I'l try throwing a ferrite bead on my Teknetics 8500 to see if I can quite it down some.
Thanks, Dan

Dan, I spent half my career working in EMC test and instrumentation,
and my father spent his entire career in the field. Which facility were you at in NY?

Sometimes solving an EMI issue is like trying to catch a ghost in a hall of mirrors,
...and just when ya think you've got the problem solved...

 

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[Quisp]

Dan, I spent half my career working in EMC test and instrumentation,
and my father spent his entire career in the field. Which facility were you at in NY?

I'm in Rochester. It was a customers in-house chamber, which was previously run by Chomerics. My career has been in product safety but our emc guy retired last year so I've had to cross over to the dark side to help out.

 

[DizzyDigger]

I'm in Rochester. It was a customers in-house chamber, which
was previously run by Chomerics. My career has been in product safety but our emc guy
retired last year so I've had to cross over to the dark side to help out.

Seen that happen many times over the years...the EMC guy retires, and
the company decides to burden another engineer with understanding
the black magic of EMC.

At least you can spell it, so you're way ahead of curve..

We were rep's for most of the major test equipment providers, and
as a result I got to work with every test facility here in the NW. You
might be familiar with some of the manufacturers we rep'd: ETS/Lindgren,
Rhode & Schwarz, Haefely, AR Amps, etc.

There's been many times I've wanted to take a detector out to
one of the labs and see if they could help reduce the susceptibility
of it to random EMI. If someone could come up with a righteous
EMI suppression kit for metal detectors I think they'd have a
winner of a product.

 

[signal_line]

Never seen anything worse than a malfunctioning street lamp. It kept trying to light. The whole area was undetectable, maybe a hundred foot radius. Whatever that is, high voltage discharge.

 

[Slowtaknow]

There has to be a way to fix/reduce emi issues in place, i agree though that getting away from the source of issue is easiest. But what are you missing around power lines, etc..?

 

[vferrari]

There has to be a way to fix/reduce emi issues in place, i agree though that getting away from the source of issue is easiest. But what are you missing around power lines, etc..?

If you think about it, a metal detector is actually a sophisticated EMI detector. It is trying to detect micro changes in electric and magnetic fields and therefore is very sensitive to EMI by its very nature (at least at the coil end). EMI getting in through the coil is supposedly addressed through the noise cancel process, but it is not fool proof and you cannot go overboard there with filtering or suppression or you will basically render the detector useless. So, yes, the best EMI solutions knock down the noise at the source (or by the detectorist picking a site without EMI - not necessarily an option in all cases), second is good coil and control box shielding and a good EMI reduction filter, then you can attack EMI getting in through conductors that inadvertently act like antennas like the coil cable. Fortunately, besides NOISE CANCEL and lower gain/sensitivity, the Equinox allows you to select individual discrete operating frequencies which can help with EMI but you lose the benefits of MultiIQ, but if it enables you to swing the coil, be confident in the fact that you have a pretty good single frequency detector too, with choices. As last ditch effort you can notch out large swaths of the TID range silencing noise that is showing up in specific ID ranges. Of course you will not be able to detect targets in that range, but just another last ditch method to allow you to swing the coil in a bad EMI situation, like an invisible electric dog fence.

 

[Quisp]

Well, I'll be taking home a few of these this weekend and if things get a little noisy, I'll snap one on to see what it does.



Dan

 

[smokeythecat]

EMI? I must be doing something wrong. The only place I ever had a problem with the Deus was in a city park next to a transformer almost as big as a Volkswagon. Other than that, no issues.

 

[laidback4sho]

Yeah, no issues with mine either - the Deus or the Equinox.

 

[smokeythecat]

If we could see the EMI in the air (or contaminants in our food) we'd all probably freak out.