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Why is the Sidewinder SCT BEC 5V?
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kazuaki
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Why is the Sidewinder SCT BEC 5V? - 01.22.2011, 06:11 PM

Just wondering why this is 5V. My standard Sidewinder is 5.67V and the new SCT version is 5.0V. Unfortunately, the lower output doesn't work with the stock servo on my SC10 brushless, which happens to be a HV unit that expects at least 6.0V. Needless to say, the steering is terrible. It work OK with the older Sidewinder. Will there be any firmware available to alter this output, or do I have to swap to a different servo?

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George16
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01.22.2011, 06:41 PM

Just install a BEC so you can get enough juice to your servo.


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kazuaki
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01.22.2011, 06:49 PM

Well, for $30, I can get a servo that is a step up from the stock one anyway. I'm just wondering why have the built-in BEC output set at 5V instead of closer to 6V? I can't think of any good reason why less than 6V would be preferred.
   
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Arct1k
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01.22.2011, 07:09 PM

Iirc the reason was that some old rx can have issues with 6v
   
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BrianG
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01.22.2011, 09:18 PM

That's a linear BEC and 5v low drop-out regulators are pretty common. Also, a BEC output of 5v on 2s lipo ensures the output won't change near LVC due to dropout.

If you want exact 6v or higher, get a BEC or one of these and add the appropriate resistors. Just be aware of the dropout.

If the servo accepts 7.4v, just run battery power (2s only) directly to the servo and have the BEC just power the receiver. This would require a bit of wiring, but nothing too complex.

Last edited by BrianG; 01.22.2011 at 09:19 PM.
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E-Revonut
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01.22.2011, 09:25 PM

OR....since it's a HV servo as long as your rx is capable of handling the voltage you could disable the bec by pulling the red wire from the plug into the rx and get a pigtail with servo plug and wire it directly into the rx from the battery. Presto! Your servo will be operating at it's full potential


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BrianG
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01.22.2011, 09:26 PM

I said that already.
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E-Revonut
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01.22.2011, 09:38 PM

Quote:
Originally Posted by BrianG View Post
I said that already.
Sorry, when I pulled up the page your last post wasn't there


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BIG-block
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01.23.2011, 08:42 AM

That's why I love my Speky receivers. They can take 2S voltage with ease. Pretty cheap too, when compared to some of the Futabas.
   
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simplechamp
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01.23.2011, 12:14 PM

+1 to that. I have always wondered if other brands could actually handle 2S even though they are rated up to only 6V. But who is going to be the guinea pig with a $60-100 RX?!?!


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bruce750i
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01.24.2011, 05:56 PM

Or let the bec run the RX, and hot wire the servo to the lipo. I've plugged 4s(MMP) into that AE HV servo on accident that way, It lived!

Would your Specy Rx live if you accidentally ran a 3s through your RX to power your servo? I don't think it would like it very long.

Last edited by bruce750i; 01.24.2011 at 05:58 PM.
   
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coreyfro
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02.14.2011, 09:54 PM

I'm glad I already have a monster, then. I was going to swap it out to save some weight, but the added weight is a small price to pay for a switching BEC.

I'll put my sidewinder in something lighter.
   
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BrianG
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02.14.2011, 10:02 PM

Quote:
Originally Posted by simplechamp View Post
+1 to that. I have always wondered if other brands could actually handle 2S even though they are rated up to only 6V. But who is going to be the guinea pig with a $60-100 RX?!?!
My Spektrum receiver has handled 5s lipo before without issues (well, sort of). I had a BEC blow and sent full 5s battery voltage to the rx and servo. The servo fried which pulled enough current to blow the PCB traces in the rx (between the power/ground pins). I bridged all the power and ground pins via a wire to replace what was blown and it's still working fine ever since.

IIRC, I was snooping around inside the Rx and there was a small linear regulator between the power pins and the actual receiver circuitry. I don't know if I'd run that high voltage for very long, but it apparently is possible.
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