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Electromagnetic Interferrence Fillters or EMI Fillters

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I have brought myself a small wood turning lathe ,a good bit of kit .......but the wife does not agree ,she likes to listen to the radio especially when outside ,but when I have the lathe on she can not listen to the radio ,due to interference from the lathe ,she likes to listen to AM stations. 

It is just like when  I was a kid someone riding a motorbike with unsuppressed plug caps drives past  the house it interfered  with our TV .

The lathe has an Inverter motor fitted ,asking the company they said fit an EMI filter ,now Lazada sell them ,but what type to buy,and looking at Google well beyond me fitting one ,and finding a  good Thai sparks in my rural  area not easy.

Anyone any ideas. Buy a new radio ?this one is new but a very old design ,would others be the same ? of course no DAB in Thailand.


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The interference is likely coming through the air, as opposed to being conducted along a mains power lead.  It is likely caused by the sparks within the motor of your lathe, so buying a new radio won't help, (unless she starts listening to FM).


Does the interference increase in speed as your lathe motor speed increases?


It's not an easy fix, because the sparks are often caused by the graphite electrical contacts on the motor. Did you buy the lathe new?  If old, you could try replacing these graphite contacts, which is usually not a difficult task - electric power drills often need these changed.


An alternative would be to see which AM stations she likes, because they are often also carried by FM transmitters.  So she could listen to them on FM, where this interference should be less or eliminated.

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HP9 has a good solution and likely easier than the alternative. 

Agree with Simon. Step 1 source of EMI

Step 2 - can it be fixed at source

Step 3 - try to attenuate source if can't be fixed. 

Could be metal panels/Farday cage for the frequencies you care about (Think microwave containing 1000w in the box but thats a higher freq so smaller slots. Probably get some cosmetically nice panels to do the trick with larger gaps on the walls. 

Could be filtering the power line but guessing it's not noise traveling back to the radio. 


Also noise should die off exponentially with distance so could also mean just moving further from noise source.  

Edited by SnowyWiez
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Probably the easiest fix suggested is to move further away. 

Also she could try the Radio Garden android app. Got lots of internet radio stations for Thailand.

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Thanks for the replies ,what I know an inverter motor is brushless ,would they be any sparks ,it was brought new .

An internet radio could be the answer , will look in to it ,but the wife is not good with the internet , it would be a learning curve for her ,but that app might work , and like an internet radio ,just preset the stations,  and she likes some specific radio stations. 

Moving away would not work, the lathe is fixed ,and the garden is not so far away .

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53 minutes ago, kickstart said:

Thanks for the replies ,what I know an inverter motor is brushless ,would they be any sparks ,it was brought new

The motor itself isn’t an inverter, that is the power supply, the motor is designed to be able to run at slower speeds without damage and they are not automatically brushless. 

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