Thread replies: 8
Thread images: 2
Thread images: 2
Anonymous
Battery Charger RF Interference 2016-02-03 22:46:55 Post No. 940920
[Report] Image search: [Google]
Battery Charger RF Interference 2016-02-03 22:46:55 Post No. 940920
[Report] Image search: [Google]
File: 1454539519644.jpg (2MB, 3264x1836px) Image search:
[Google]
2MB, 3264x1836px
When I plug my Milwaukee battery charger in at work, my boss' Makita radio goes to static. I've never had this problem when using a Milwaukee radio, and the Makita radio works fine with the Makita charger. So it looks like the switched mode power supply in the charger is causing rf noise that neither the radio or charger has adequate filtering to remove. I tried just moving the two away from each other, but there was no improvement in the sound, so it looks like the rf harmonics are traveling through the wires instead of just through the air. The two work fine when they're plugged into outlets on different circuits, but this isn't always possible. I was thinking that adding an rf choke into the power supply of the drill charger might fix this problem, or putting a large cap across the hot and neutral wires. I'm an electrician so I know how to safely work with electricity, but I don't know if this is going to work or if I'm gonna screw up my charger. Much thanks for any help.
>>
Does it mess with AM or FM?
>>
We've only used the radio on FM
>>
It's because hackers
>>
File: Image1.png (14KB, 470x238px) Image search:
[Google]
14KB, 470x238px
My guess would be that the charger is two wire main. That means it is dumping its excessive rf noise into the neutral wire instead of the ground. To stop that you need to make a line filter that is tuned for around 100 Mhz. If you look at this PDF fig 3 has a diagram for the filter.
http://www.we-online.com/web/en/index.php/download/media/07_electronic_components/download_center_1/application_notes_berichte/netzfilter___letzte_huerde/TR_Netzfilter-Die_Letzte_Huerde_im_Schaltnetzteil_EN.pdf
I've attached a screenshot of the diagram. The main parts of the filter is a properly sized choke, capacitor, resistor to discharge capacitor when unplugged, and they add a fuse for safety and varistor to trap surges.
>>
Also here is a premade solution if you don't want to diy. http://www.okaya.com/products/noise-surge/noise-filter/single-phase/ Google ac radio frequency interference power line filter for more.
>>
Awesome thanks dude, that should do it
>>
I just realized my charger has a two prong cord and no earth ground to divert the noise to. Also, idk how it stands for engineers, but I know that by the US national electric code, you are NEVER allowed to intentionally put any current on the earth ground, not even the tiny LED lights in a dimmer switch. Not that would be a problem here, but what if I just put an rf choke in series with the neutral?
Thread posts: 8
Thread images: 2
Thread images: 2