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Wavess

Avoiding Switching noise

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Hi all, this have been discussed many times here, but I still haven´t found the best way to solve it accurate.

I have on my Mikrokopter this Ubec

http://www.unitedhobbies.com/hobbycity/store/uh_viewItem.asp?idProduct=4319

for powering servos on tilt, shutter and so on.

And have another dedicated 5v linear reg for powerering the fpv gear:

1 Airwave 40mW 2.4ghz Tx

1 DPC-171 ccd cam

If I run the power from the main battery I see those horizontal lines on the video. If I run the fpv gear with a dedicated battery the video is clear.

I have tried to do a LC filtering with caps and an 330uH resistor´s style inductor in series with the +5V line. This reduced a bit the noise but not all.

Then I tried with a 470uH power inductor this one

http://es.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=233-5279

The result with this one is worst than with the 330uH resistor´s style

Looking at the Switching frequency of the Ubec it tells 300khz. I assume that I have to go to a higger value on uH to match that resonant frequency but how much?

BTW I´m placing this LC circuitry close to the video TX basically because the room on the Mikrokopter is not much to put it where I want.

How to determine the best value for the inductor to have a clean video with a single battery?

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Something is just not right. How about posting a wiring diagram that shows your video system's electrical layout?

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Something is just not right. How about posting a wiring diagram that shows your video system's electrical layout?

ok I will ASAP

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here we go

uploading directly through the forum didn´t work (got server error message)here is an external host

electricalsquematic1.th.jpg

Edited by Wavess

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Are you talking about interference from the UBEC or the motors?

Terry

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Are you talking about interference from the UBEC or the motors?

Terry

When I power up the video motors off I see some kind of lines across the screen, they go worst while motors on. So I assume both are putting noise out.

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I can see the wheels turning in Terry's head. :)

Let's just shotgun this. Do this:

post-2-125804776501_thumb.jpg

The two new inductors must have a low DCR rating and be able to handle >300mA current. The RS #233-5279 you selected should be fine. The diode must be 1A or greater rated Schottky type (1N5819 is common).

If this does not fix it then there is something you are not telling us!

uploading directly through the forum didn´t work (got server error message)

Looks like the new software upgrade has problems with attaching jpg and gif files. I'll get that fixed.

EDIT: FIXED FILE UPLOAD ISSUE

Edited by Mr.RC-Cam
FIXED FILE UPLOADER

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I can see the wheels turning in Terry's head. :)

Let's just shotgun this. Do this:

post-2-125804776501_thumb.jpg

The two new inductors must have a low DCR rating and be able to handle >300mA current. The RS #233-5279 you selected should be fine. The diode must be 1A or greater rated Schottky type (1N5819 is common).

If this does not fix it then there is something you are not telling us!

Looks like the new software upgrade has problems with attaching jpg and gif files. I'll get that fixed.

EDIT: FIXED FILE UPLOAD ISSUE

Ok great thanks for the schematic, would try that as soon as I get a proper diode to install.

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