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Thread: $1.53 Step-down switching regulators - Usefull or not?

  1. #1
    I can't breathe Hans's Avatar
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    $1.53 Step-down switching regulators - Usefull or not?

    Credits to Volto for pointing out these Voltage Stepdown switching regulators to Chicken Sashimi, and then Chicken sashimi for posting this tip on the Lab.

    http://fpvlab.com/forums/showthread....482#post168482

    Quote Originally Posted by Hans View Post
    Thanks for the tip
    I've ordered a few at 50% off. Even when they are crap, they're still good enough to power some leds or a photocamera or whatever
    You can get them here: http://www.ebay.com/itm/1pcs-DC-DC-B...item3a74b337d4

    ***Fun fact: check your local supplier for the price of a single LM2596S

    After 19 days, this is what you get. A strip of 5 regulators, ready to be separated:




    ...But always check your goods to avoid nasty suprises (I forgot if the Chinese was either: 'This concert sucks like a cows vagina' or 'You are not educated':


    Let's get some voltage on the outputs. Using a 3S Lipo, i trimm the pot to about 5 volts:



    I use a 3S Lipo at about 11.40 volts as my supplyvoltage. I have already checked the range of the voltage regulator and it does what the description says: From 1.23 volts to 35 volts, depending on the input. The load for the first test is a geared motor that works from 1 volt to 22volts. Motors are known for bad noise, so here we go:



    Open end supply, NO motor as a load:


    Now with the motor running:



    Next tests will be to so if i get any nasty noise in my video when using these voltage regulators as the main powersupply for either my Fatshark 250mw Vtx or my ImmersionRC 600mw Vtx.

    If i do this the wrong way, please let me know to get more acurate results

  2. #2
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    Awesome! I was just going to build something like this! but for 1/2 the price of the regulator I can have the Chinese build, possibly test, and ship them to me!

    Hmmm...
    Build my own...
    --Chip from manufacturer $2.35+$3 shipping
    --Other components from local shop $15
    --Total ~$20 (for 1)

    Buy these...
    13 Chinese assembled regulators for $20

  3. #3
    Super Moderator Coyote's Avatar
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    I was talking with Sander the other day about some diagonal lines on my video footage. They did not react to throttle etc, just static.

    I tried all sorts of fixes, LC Filters, different cabling etc etc but the lines were still there. If I reduced the output from them down to 9v the lines nearly went away, or were at least hardly noticeable.

    After a quick chat with Sander it became apparent it was these units above conflicting with the switching regulators on board the camera and Vtx. I then realized that I only have this faint diagonal banding on the planes I have these fitted too, so it became pretty obvious they were as Sander thought the problem.

    I removed them and surprise surprise, diagonal lines gone
    "If everyone is thinking alike, then no one is thinking."

    - Benjamin Franklin

  4. #4
    Reckless Video Operator squishy's Avatar
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    I have what looks like the same thing in a metal shield, here it is: http://www.bevrc.com/voltage-regulat...dule_p143.html

    So far so good, I am using it on a 4 cell quad, LC filter after it and all seems to work very well.

    I also purchased the above regulator, without the shield and I will be placing it in a skywalker, I am curious if there's much of a difference between them.

    I also have one of these in the mail, looks cool with the voltage display on it, but I have no idea if it will work as well: http://www.ebay.com/itm/370700146811...84.m1497.l2649
    Flight Club - "In thrust we trust"

  5. #5
    Navigator fmkit's Avatar
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    These have switching frequency of 50kHz, such low frequency more difficult to filter -need large heavy choke and ceramic cap. The switcher is good to power digital servos.

  6. #6
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    Quote Originally Posted by fmkit View Post
    These have switching frequency of 50kHz, such low frequency more difficult to filter -need large heavy choke and ceramic cap. The switcher is good to power digital servos.
    ya, I was planning on using them as BEC's and building my Redundant BEC some day...

    Chris

  7. #7
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    What you're doing is testing for load transient response. It's not surprising that the converter didn't perform perfectly, as it wasn't really designed to switch motors.

    A more informative test would be output ripple at say, 500mA, with a steady input voltage. Or output ripple when an ESC is making 500mV of ripple on the input power rails.

    EDIT: Do you know how to AC couple your scope? You could get more informative measurements if you did

  8. #8
    Navigator guy1a's Avatar
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    Hi

    I use those for about a year now. They survive pretty good.

    Jave on planes and one on my ground station ...
    FPV piloting ... too much fun

  9. #9
    FPV Addict Scotttu's Avatar
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    Quote Originally Posted by Coyote View Post
    I was talking with Sander the other day about some diagonal lines on my video footage. They did not react to throttle etc, just static.

    I tried all sorts of fixes, LC Filters, different cabling etc etc but the lines were still there. If I reduced the output from them down to 9v the lines nearly went away, or were at least hardly noticeable.

    After a quick chat with Sander it became apparent it was these units above conflicting with the switching regulators on board the camera and Vtx. I then realized that I only have this faint diagonal banding on the planes I have these fitted too, so it became pretty obvious they were as Sander thought the problem.

    I removed them and surprise surprise, diagonal lines gone
    I have four of these sitting waiting, they are right at 5.1v out of the box.

    I figured I would wrap them in electrical tape or heat shrink and then mylar foil or alum foil and test.

    I just got them to play with since they are so cheap.

    I love the NGHobbies regulator for the $18 but seems about the same, 3 miles out I started getting diagnal bands.

    Never saw those with TBS Core but then I mounted it on the wing far enough away from anything.

    For a close in FPV - these are a sweet ticket item, I would probably be hesitant using them on long range.
    "Truly superior pilots are those who use their superior judgment to avoid those situations where they might have to use their superior skills"- Author unknown

    KF7TRX

  10. #10
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    For DYI this tricopter how to also has a 4S => 12v linear regulator howto near the end, which work fine http://rcexplorer.se/projects/2012/0...copter-v2-6hv/

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