image
Page 9 of 9 FirstFirst ... 789
Results 81 to 89 of 89

Thread: 12v regulator or straight from 3s lipo?

  1. #81
    FPV addict ke123's Avatar
    Join Date
    Jan 2012
    Location
    Edmonton, Alberta
    Posts
    696
    I reported no noise on the canless version using it to power the video equipment off of 4S.. But that's with an additional LC filter in line with it. I will put it on an oscilloscope when I get a chance to get something more quantitative for the 'lab.

    I have the 3G combo version of the RF explorer good from 15-~2700MHz. I don't have the canless version of that regulator to test it..

    edit: I didn't actually bother to test the 2A regulator for video _without_ an additional LC filter as it's cheap insurance and Whakahere had told me in PM's that he noticed it threw noise into the video unless one added an LC filter.. he also mentioned that the 3A version had less of an issue with noise.
    Last edited by ke123; 7th December 2012 at 02:48 PM.

  2. #82
    Navigator
    Join Date
    Nov 2012
    Posts
    62
    Thanks for all the great info!

  3. #83
    FPV addict ke123's Avatar
    Join Date
    Jan 2012
    Location
    Edmonton, Alberta
    Posts
    696
    So as promised, for those interested in using one of these in a build I looked a little deeper into these SEPIC regulators that I linked earlier

    The 2a max version ($6)
    http://www.ebay.ca/itm/160895562573?...ht_2561wt_1105

    The 3a max version ($12)
    http://www.ebay.ca/itm/160885862679?...ht_2252wt_1105

    The 2a max version I was told by Whakahere is prone to giving rise to more video noise than the 3a max version. I run it through an LC filter on my quad (made up of a 25V 1000uF capacitor and a small-ish surface mount common mode inductor) and it works great for feeding the video.

    This is the 2a unit:


    Here's that unit hooked up to my oscilloscope, running off of a 3S battery at storage charge and set to output 12V. The ripple current is as advertised on the seller's ebay store (~40mV):


    This is the 3a unit:


    Oscilloscope read. The ripple current is MUCH larger than the 2a unit, 100+ mV, there are also a couple of different waveforms with different frequencies going on. The ebay seller advertises less than 40mV ripple but it just isn't true:



    Now as for the question of whether these SEPIC regulators output significant RF interference, I did some measurement with my RFexplorer while these were putting out 12V driving a load (2 video receivers located 7ft away).
    I used a Nagoya 433MHz antenna for the 433MHz band measurements, a 1.258 GHz tuned cloverleaf for the 1.2ghz band measurements, and a stubby 2.4ghz antenna for the 2.4ghz band measurements. All tests were done with the antennas point blank to the regulator.

    433MHz band:
    Noise floor (a bit high in the room from other equipment that I couldn't shut down):


    2a regulator running:


    3a regulator running:


    1.2 GHz band:
    Noise floor:


    2a regulator running:


    3a regulator running:


    2.4ghz band:
    Noise floor:


    2a regulator running:


    3a regulator running:



    So there's a little more objective data on these. Best bet for FPV is probably the 2A regulator. The LC filter on my quad reduces that ripple current to around ~15mV and I don't see anything in the video to date. Mind you I haven't tested the 3A regulator for powering video and camera as I haven't needed 3A on any of my ships. But the specs given by the ebay seller don't appear to be correct for that one.

    As for RF interference, while the noise floor in my testing room was a bit high around the 433MHz band (unavoidable), the antenna was _point blank_ against the regulator for testing. They both seemed to be very RF quiet across all the common bands. The only thing of note was a slight bit of noise around ~1200 MHz with the 3A regulator, oddly only as I first powered it up (it's not shown in the picture), it was a very small amount and wouldn't affect anyone using 1258 MHz or 1280 MHz for video.

    Cheers,
    Kris
    Last edited by ke123; 11th January 2013 at 07:52 PM.

  4. #84
    Navigator
    Join Date
    Aug 2011
    Posts
    387
    Wow amazing data, thanks Kris. 2A with LC Filter it is, then

  5. #85
    FPV addict ke123's Avatar
    Join Date
    Jan 2012
    Location
    Edmonton, Alberta
    Posts
    696
    I altered the post above - I have to revisit the RFexplorer data to make sure I didn't read with the wrong module or something

    Edit: I redid the measurements to make sure, and added the 2.4ghz band. Used a more sensitive module for the 433MHz measurements too.
    Last edited by ke123; 11th January 2013 at 07:52 PM.

  6. #86
    Sky Pirate & FPV Outlaw SecretSpy711's Avatar
    Join Date
    Dec 2011
    Location
    Denver, CO
    Posts
    4,936
    On my 3S Deep Reaper, I run power through a couple of diodes to drop the voltage, then feed that into an adjustable BOOST regulator (looks almost exactly like the SEPIC) and then through an LC filter. I ended up winding my own common mode inductor and there were still some lines because I could only get so many turns, so I added one more inductor and that solved the problem. No lines in the video now. Using the diodes on the regulator input ensures that it always sees less than ~11v, even on a fully charged lipo, giving the regulator the ~1v difference it needs to do its job and boost to 12v. Granted, there is some lost power as heat in the diodes, but to me that is negligible.

    On my 4S quad that I'm building, I'm using the SEPIC version of the same regulator (without the extra diodes), but the Foxtech 5.8 vTx is supposed to have good filtering so I don't have an LC filter planned. Will add one IF it needs it.
    Last edited by SecretSpy711; 11th January 2013 at 01:15 PM.
    youtube.com/secretspy711
    COFPV.com

  7. #87
    FPV addict ke123's Avatar
    Join Date
    Jan 2012
    Location
    Edmonton, Alberta
    Posts
    696
    sounds like a good setup. I've started using surface mount common mode inductors that I can get off of ebay for like $1-2 and they work much better (judged both by video quality and oscilloscope measurement) vs. hand-wound servo wires around soft ferrite rings.. and smaller too.

  8. #88
    Banned
    Join Date
    Feb 2013
    Posts
    2
    Hi everyone! Just in case it hasn't been mentioned, the V1 and V2 from trainaidsa.com might be suitable for some here. Just ordered V2 and can let you know later of my experience/s with it.

  9. #89
    Banned
    Join Date
    Feb 2013
    Posts
    2
    Sorry, I think that was a typo :-|

Page 9 of 9 FirstFirst ... 789

Similar Threads

  1. TBS LiPo - super-durable, high voltage lipo
    By Trappy in forum Team-Black Sheep
    Replies: 81
    Last Post: 9th October 2013, 12:45 AM
  2. Replies: 13
    Last Post: 1st July 2013, 07:27 AM
  3. Sander Style EZUHF antenna placement on a Straight Wing platform (skywalker)
    By ajhaggerty in forum IFR - Video Link Discussion
    Replies: 17
    Last Post: 23rd June 2012, 03:13 PM
  4. RiteWing ZII - Keeping the Wings Straight
    By CAM71 in forum RC TECH
    Replies: 9
    Last Post: 7th June 2012, 11:05 PM
  5. Pan Tilt on Quad that can look straight down?
    By schnellschnell in forum ROTORCRAFT
    Replies: 0
    Last Post: 13th April 2012, 03:23 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •