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Takeing power from main batt for video tx?

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Old 02-11-2004, 08:07 AM
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SpaceCase
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Default Takeing power from main batt for video tx?

Iv got a corona and was thinging of useing the main batt for power for a black widow 5v tx. I would just use a "Y" harness from the speed controlers's bec? Anyone?
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Old 02-11-2004, 01:25 PM
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yb2normal
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Default RE: Takeing power from main batt for video tx?

I think you are asking if you can power the tx from the bec's output, and I would recommend not. There are two reasons for this.

First, you are putting an extra load on a critical part of your flight system. It would not be good if your bec thermalled on you!

Second, you would effectively be sharing the same power sources as those (electrically) noisy servos. You will very likely see lines when you work the servos.

I generally recommend that people share the main battery directly, and add a 5v regulator (and caps!) to the tx. This provides the lowest noise installation in my experience.

Regards,
Bill
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Old 02-12-2004, 07:26 PM
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Default RE: Takeing power from main batt for video tx?

I think that sounds good, I can get a 5 volt regulator from where? Tower might have this. Also what are "caps"?. Capacitors? If you might tell me wich ones I would greatly apriciate it!!!
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Old 02-12-2004, 07:41 PM
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Default RE: Takeing power from main batt for video tx?

you should be able to get a 5v reg and caps from radio shack in west leb. The regulator might suggest caps.

Do you fly a camera in norwich?
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Old 02-12-2004, 07:55 PM
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Default RE: Takeing power from main batt for video tx?

If you aren't comfortable with electronic design or soldering then I would suggest a ready-made 5v regulator. There are two that come to mind:

1) The "super-bec" or "u-bec" type switching regulators that allow you to power your receiver from high cell-count batteries. I have successfully powered my 5v transmitter from the 's-bec' from firmtronics.com

2) A regulator designed for lithium battery packs. These batteries are becoming more and more popular but they put out a nominal 7.2 volts, so designers are creating voltage regulators to bring the voltage down to 5v for our receivers. There is no reason you couldn't plug a transmitter into one instead of a receiver!

Bill
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Old 02-14-2004, 09:33 AM
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Default RE: Takeing power from main batt for video tx?

I just ordered the s-bec from firmtronics for use with my recently ordered 200mw 2.4 GHz system. I was planning on a linear regulator, but with my 7 cell flight battery I guess I would be wasting power (3.4v delta * .5a = ~1.7w (linear) vs. 5v * .5a * 1/.85 = ~.4w (switched)) and heating up the regulator. With an 85% efficiency, I guess a switcher is the way to go. I also think it might be tough to get a linear regulator under 8 grams with caps.
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Old 02-14-2004, 09:42 AM
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Default RE: Takeing power from main batt for video tx?

I try to fly some times here in Norwich, been too windy and cold now. And my Ap plane is down for now. Thats cool you are in Hanover. I have some Ap shots of Hanover And Norwich you might like!!
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Old 02-14-2004, 09:56 AM
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Default RE: Takeing power from main batt for video tx?

I know what you mean. I have not flown since early January. I am in Portsmouth NH. It looks like another windy day out there today...
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Old 02-14-2004, 04:02 PM
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Default RE: Takeing power from main batt for video tx?

My lastest video was shot with a BWAV system powered by a 2C 1020mAh Kokam LiPo pack using a 5v regulator that FMA sells. Bought the pack and the reg together from FMA. Its sold to be used for a rx pack but works great for my 2.4ghz video tx! The reg has LEDs to let you know how the battery is too.
ORIGINAL: yb2normal

If you aren't comfortable with electronic design or soldering then I would suggest a ready-made 5v regulator. There are two that come to mind:

1) The "super-bec" or "u-bec" type switching regulators that allow you to power your receiver from high cell-count batteries. I have successfully powered my 5v transmitter from the 's-bec' from firmtronics.com

2) A regulator designed for lithium battery packs. These batteries are becoming more and more popular but they put out a nominal 7.2 volts, so designers are creating voltage regulators to bring the voltage down to 5v for our receivers. There is no reason you couldn't plug a transmitter into one instead of a receiver!

Bill
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Old 02-15-2004, 10:56 AM
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Default RE: Takeing power from main batt for video tx?

Can I use the regulator fma sells on regular 7 cell nimh batteries?
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