Anybody with experience with reading tiny amounts of EMF an inch away the contacts of an electromechanical timer as it switches internally? If I can do "before & after" measurements putting properly grounded barriers & shielded wiring it could helpful. That way I can see how much each step helps & if the only solution is to move an Arduino I2C LCD a tiny bit farther away from the 200 terminal washing machine electromechanical timer.

Will the following Gauss Metera or similar AC EMF Gauss have that ability?

https://www.amazon.com/Gauss-Magnetic-Field-2000mG-Meter/dp/B00MNEFCI6/ref=cm_wl_huc_item

https://www.amazon.com/KKmoon-Handheld-Electromagnetic-Radiation-Dosimeter/dp/B073W7MPNN

 

Hold a scope probe with a wire on it close to where you want to read the EMF.

 

Hold a scope probe with a wire on it close to where you want to read the EMF.

Thanks for the answer ... I was hoping that the Gauss-Elf approach could be another less costly alternative. One guy said that an AM radio in between stations holding the antennae would tell a general intensity by way of the increased static. That is a bit too crude so I did not try that.

I have a Fluke 325 & a Fluke 771 meter .. if it is do-able with one or both of those. I never did invest in the more "gold standard" oscilloscope approach to testing electronics.

 

You may also be able to detect a field change using a FET with an antenna connected to its gate and an Ohmmeter connected from drain to source. Not guaranteed to work, though.

 

what exactly are you trying to measure?

 

what exactly are you trying to measure?

kubeek& others,

The Arduino I2C LCD works perfect during the whole 35 minute process when I move it away from the washing machine timer so I know that the problem is with some sort of electrical noise emitting from the timer contacts as they switch. That intensity of EMF??? that is between the timer & the LCD would be nice to see in terms of the amount of mG??? That way after I build a grounded on one side enclosure over the back of the LCD or other step that I take to solve the intensity problem... I will be more sure as to how much good each step did. Shielded Beldon wire is on its way so that is another step that might help. I have some 3M shielding tape which could also be part of the steps that may or may not be needed.

 

kubeek& others,

The Arduino I2C LCD works perfect during the whole 35 minute process when I move it away from the washing machine timer so I know that the problem is with some sort of electrical noise emitting from the timer contacts as they switch. That intensity of EMF??? that is between the timer & the LCD would be nice to see in terms of the amount of mG??? That way after I build a grounded on one side enclosure over the back of the LCD or other step that I take to solve the intensity problem... I will be more sure as to how much good each step did. Shielded Beldon wire is on its way so that is another step that might help. I have some 3M shielding tape which could also be part of the steps that may or may not be needed.

Check the datasheet for the tape. I doubt it attenuated anything at 60Hz. It is intended for higher frequencies. You'll need more than tape for 60Hz.

 

I just read that grounded enclosure that I was referring to is technically called a Faraday Cage. The ability to measure the EMF could affect how that is constructed possibly. Hopefully, an expert can share something about what would be the most likely pattern of construction of the cage that would be the best fit for the 60hz line voltage 110 & 220 source of the ambient EMF.

 

If the Arduino is outside the machine and the machine is properly grounded, then the machine casing is a Faraday cage preventing internal fields from affecting the Arduino. Or is the Arduino inside the machine?

 

If the interference is only during the switching, it’s probably not 60Hz. More likely a higher frequency propagated RFI.


Abbreviations corrected since this appears to be abbreviations lecture day.

 

If the Arduino is outside the machine and the machine is properly grounded, then the machine casing is a Faraday cage preventing internal fields from affecting the Arduino. Or is the Arduino inside the machine?

Alec_t,

The Arduino SparkFun Uno Clone Redboard is & has to be inside the machine. So ... the need for more than just the metallic frame of the washing machine as the Faraday. Thanks

Elect' e, Can a higher frequency rf cause the I2C LCD to go blank or have uncoded unintended ASCII characters?

 

Depends on what the device is susceptible to, and what kinds of problem it causes. Hard to answer really.

 

To what else is the arduino connected apart from the power supply and lcd?

 

I spent months struggling with similar issues on a very sensitive LCD package. I'm pretty confident that @ElectricSpidey is right about high frequency switching noise, as opposed to 60Hz hum, being the problem.

Can you eliminate the noise at the source? Snubbers across the relay contacts, or in parallel with the switched load, can make a huge difference in the amount of arcing you get when switching the load. Replacing the relays with SSRs will reduce switching noise even more than snubbers (that was ultimately what solved this problem, and several other, for us.)

I could be way off base, but I'm skeptical about shielding saving the day. Will the wires to the display still have to pass through the rest of the machine (I'm assuming yes?) I'd guess that the noise is being induced into wires to and from the display, not the display itself, and that shielding the display won't do any good unless you're also protecting all relevant wiring.

Grounding issues also seem a likely candidate. In our scenario, we had crummy grounding but we were kind of stuck with it and just had to do the best we could with a bad situation. How is the display assembly grounded? Are you employing "star" grounding techniques? If not, you may want to consider them.

Just to be clear, I'm the farthest thing from an expert on any of this. All of my opinions above could easily be wrong. However, your experience sounds very similar to what I've been through not that long ago, so I thought I'd share my experiences.

 

To what else is the arduino connected apart from the power supply and lcd?

I appreciate the discussion.
The reason why I am pretty sure that the noise to the back of the I2C LCD is the cause is because when I move the LCD & its 4 wires the problem goes away. The other switching works perfectly along with the LCD as long as the LCD is moved away from the timer contacts. The SDA & SDL wires & the ground & 5V wire are not the problem or it would not be so reliable when I move the LCD. As a precaution, I will use 22 gauge Beldon Shielded ... just in case. The purpose of this thread was mostly to have input from people who have used an Elf Gauss meter in this kind of situation to see if one is making headway in the area behind the LCD.