Using a BNX022 as an LC Filter

[iPeel]

For those that like their video feed crystal clear, using an LC Filter is a necessity for clearing up ESC and other noise from the video image. An LC Filter is easy to knock up but the coil and capacitor can be quite bulky, especially on a 250 sized quad.

I decided to buy a bunch of BNX022 filters and see if they were any good, it turns out they are extremely good! I bought a pack of 10 from Farnell which ended up being £3.92 each:

http://uk.farnell.com/murata/bnx022-01l/filter-power-emi-10a/dp/1114996

The device is pretty compact and can draw 10A at up to 50V:



It's supposed to be a surface mount device so soldering is a bit tricky, looking at the back of them the pins are as follows:



I just wet each of the pads with solder and tacked the supply and load wires, allowing them to cross over the back of the unit:



The reason why I crossed them over was so that I could then glue everything securely with hot glue:



Then when it's wrapped in heat shrink it makes a nice neat LC filter:





They probably end up costing a little more than an LC Filter but they're very quick to knock together and make a much more compact filter.



Neil.

[Dizzy]

A very neat job well presented too :D

dizzy :)

[iPeel]

It actually is an LC Filter so does just as well as one you make yourself.

[g4uvz]

So you use one feeding the transmitter which then supplies the camera 5 /12 volts.. Or do you use one between the transmitter and camera?  As there is an inductor in the 'earth line' ..do you therefore just have a single conductor from the camera 75 ohm output? otherwise the earth conductor will be shorting out this part of the filter?  All  very theoretical ..but it obviously works !..If you have any spare I would be very interested to try one
Kind regards

Adrian

[CurryKitten]

Looks good, much more compact looking than the normal effort.  I could do with adding some around - I get a little bit of noise on my Falcon, but I'm running the little very basic OSD that going inline with power and video and that really seems to introduce loads of noise into the signal.

[Ratty]

Nice work. Looks like a nice small way of clearing up interference. Certainly a lot cleaner than a "normal" LC filter.

[Flyboysee]

BIG LIKE!

[iPeel]

So you use one feeding the transmitter which then supplies the camera 5 /12 volts.. Or do you use one between the transmitter and camera?  As there is an inductor in the 'earth line' ..do you therefore just have a single conductor from the camera 75 ohm output? otherwise the earth conductor will be shorting out this part of the filter?  All  very theoretical ..but it obviously works !..If you have any spare I would be very interested to try one

On my quad I'm feeding the VTX and camera from this alone. On my Skywalker and Z3 one of these feeds the MFD input and then the cam and VTX are powered from the MFD. I guess you could short pins 3 and 4 to get a common ground?

[Coyote]

Nice and compact, nice :)

[rob.thomson]

Incase anyone feels technically challenged...

http://www.ebay.co.uk/itm/261390391865?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Some enterprising chap has started to make them with a small pcb.

I have tried some and can confirm that these seem to be a 100% effective filter.  And VERY compact.

[mrwilljackson]

Anyone fancy selling on a couple of BNX022 - the postage is a killer for such a small item, and I have no excuse to order any electronics at the mo :+

cheers  :D

[rob.thomson]

Only takes a bit of time...

http://hobbyking.com/hobbyking/store/__68126__L_C_Power_Filter_0_7A.html?utm_campaign=180315.UK&utm_content=91953994&utm_medium=email&utm_source=EDM

Not sure it is a BNX022.. but certainly similar

Nice and cheap too!

[iPeel]

It's only rated up to 14v at 0.7a so limited really in what you can drive off it unless those figures are very conservative. By the looks of the choke though the 0.7a rating is accurate.

[iwan_canobi]

Yeah, I saw this this morning, its just an LC filter made from SMD components rather a discrete solution like the BNX022.