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transmitters and power draw

Discussion in 'FPV (First Person View)' started by QYV, Jul 28, 2014.

  1. QYV

    QYV

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    I saw someone claim recently that the Immersion RC 600mW transmitter pulls less power than a Boscam TS352 500mW. I'm trying to figure out the validity of the statement of course, and this is a piece I don't really understand well so I'm trying to learn how exactly that determination is made. I've been googling trying to figure out the power consumption of the devices and the only thing I'm seeing on the IRC is it draws "2.2W" or sometimes "3W".
    but I don't see anything like that on the Boscam devices when I search for TS352 power consumption. I could find this...
    [​IMG]
    but I can't find anything like that for the IRC for comparison?

    If someone doesn't mind, I'd love to learn how to read those charts for myself so I can go compare a few transmitters so I can see for example how much the power draw difference is between a TS352 vs a TS353 (400mW) I'm thinking about dropping down my transmitter power to try to increase flight time. My TS352 is rock solid out past 600m just with the set of FPVLR pinwheels I have, haven't even gone to the helix antenna yet so I feel like I could drop transmitter power
     
  2. OI Photography

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    I don't know the exact power draw differences between those units, but I would be surprised if changing from one to the other has any useful impact on flight times. The amount of current they draw is very very small compared to the motors...even when you look at the power used by all the onboard electronics combined that's still a small fraction of the power used to actually make it fly.

    I'm not saying you won't get any dividends at all from changing the vTx, but they may be so small that you'll have difficulty quantifying them in normal flying.
     
  3. Buk

    Buk

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    You can use this web page to explain how to figure watts.

    http://videos.cctvcamerapros.com/voltage-to-watts-conversion

    basically multiply mA by 100, multiply that times volts and you get watts
    from your chart 550mA at 12volts
    550mA X 100 = .55Amps
    .55 X 12volts
    6.6 watts

    Perhaps this has a fan compared to the Immersion which does not have a fan for cooling?
     
  4. QYV

    QYV

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    hey man. Yep I know that's the general consensus around here but here's a fact: my original P2 with H3-2D and Boscam 200mW got me darn near 20 minutes of flight time (100% to ~30%)
    my new P2 with H3-3D and Boscam 500mW I feel like I'm lucky to get 15 minutes of flight time.

    Then a guy in one of the other FPV threads was trying to convince someone to go with the IRC 600mW vTx because they said it had "significantly less power draw than Boscam transmitters" so I am trying to research that.

    Now I also think part of my flight time problem is that the H3-3D seems to work MUCH harder than the H3-2D... I'm sure you've seen my other thread where I can tell the motors are running hard pretty much all the time especially if I try to aim the camera straight so I'm thinking that might be part of the issue... but like I said I was also curious about the different power draw of these transmitters so I can add that piece of knowledge to my toolkit when I'm discussing different FPV options with folks.


    thanks Buk I'm definitely going to dig into this. That's over twice what the ImmersionRC 600mW vTx claims on it's website to draw.
    There might not be a huge difference in say a Boscam TS352 vs a TS353 but 6.6W for a Boscam TS352 vs 3W for a IRC 600mW has to have some sort of impact on Phantom battery life!
     
  5. QYV

    QYV

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    I'm already proving myself wrong. A TS353 400mW only has a 220mA draw, compared to 550 for the TS352 500mW. I can already tell that's less than half, and doing the math per Buk's conversion page it's telling me the TS353 only draws 2.6W compared to 6.6.

    I think I'm going to give the TS353 a shot. With any luck it's the TS352 and it's fan maybe causing these weird problems with my gimbal.

    The next thing I don't understand is that the TS832 (600mW) and TS353 (400mW) both say they only draw 220mA. How can one be putting out an additional 1/3 power output with the same input?
     
  6. chuddly

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    The better way to look at it is this way. The "stand by" time (motors not turning but everything powered on) on a P1 (stock) is right about 8 hrs if I remember right. And the flight time is about 10 min. If you put FPV on it the flight time drops to about 8 min. So the motors are the MAJOR draw (as we all would have guessed). But the difference between having FPV and not having it is about 20%. So even if the difference between the 2 systems is as massive as you say your talking about maybe 30 seconds of flight time difference AT BEST. I would guess its closer to 10 second flight difference if any at all. So your talking about next to nothing.
     
  7. QYV

    QYV

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    okay, fair enough. I legit believe that the gimbal is the main problem I just want to make sure I'm not being wasteful with an overpowered vTx.
     
  8. OI Photography

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    I've never tested the boscam vTx's myself, but back when I started adding components to the Phantom I put a current sensor on so I could measure the real-time draw of different parts and combinations. Even if the models you're looking at draw twice the power as my Immersion 600mW or more, I think it still won't make a worthwhile difference in flight time...30 sec would surprise me.

    You'll probably get more variance in flight times due to temp/pressure changes in the air than this would net you. But, if you're going to try the 353 I'll be interested to see what the real world impact is.