Can Futaba receivers handle 8.4 volts? - HeliFreak
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Old 04-23-2010, 02:03 PM   #1 (permalink)
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Talking Can Futaba receivers handle 8.4 volts?

I'm in the process of adding a new heli to my fleet. I have decided to use outrage cyclic and tail sevo. I am going FBL. The sevos can take 8.4 volts. My question is if futaba receivers can?
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Old 04-23-2010, 02:05 PM   #2 (permalink)
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Not officially and even unofficially I know some guys that tried it but had some failures later.

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Old 04-23-2010, 09:10 PM   #3 (permalink)
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Is there anything I can do? What's the purpose of having all servos being able to to handle 8.4 if your receiver can't?
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Old 04-23-2010, 09:29 PM   #4 (permalink)
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Run a regulator after the RX.
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Old 04-23-2010, 10:12 PM   #5 (permalink)
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No way.....6v is their celing..in the 35%+ planks I used 8.4 Lipo packs and a power expander to supply the rx unit with steady 4.8v - 5v & power the servos with 8v signal.....going higher than 6.5 volts into the rx would likely kill it over time.....the power expander was from chief aircraft and not cheap, but worth it....a voltage regulator is another option...

Course I was also running 10 - 12 digital ultra hi torque servos, and ya aint powering that many with most rx units.
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Old 04-23-2010, 10:16 PM   #6 (permalink)
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Depends on the rx you are thinking off.
I know for a fact that the R6106 line does.
It is listed as 3.3~8.5V regulated output on the leaflet that comes with the rx.

Not sure how much does the regulated part is important, but the lipo will be inside the operating range, so I think it should be ok.
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Old 04-23-2010, 10:18 PM   #7 (permalink)
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+1 fixnfly70

From Futaba FAQ:

Can I use 6v (5 cell) receiver packs with my Futaba receiver/servos? Will I get increased performance from my equipment? Are there any drawbacks to using 6 volts?
All Futaba systems are designed to operate on either 4.8 volts (NiCD 4 cells) or 6 volts (Alkaline 4 cells OR NiCD 5 cells), except certain servos which are specifically labeled for use at one voltage or the other only. Some manufacturer's systems are not designed for and do not operate well on 6 volt, but most Futaba equipment handles the increased power input and provides increased performance, speed and torque.
Please note that while 6 volts provides you more torque and speed from your servos, it also provides you a significantly shorter run time for the same milliamp hours of capacity and may shorten the life of your servos proportionally. This sounds confusing, so it may help to compare the current in the battery to water in a bucket. If you have four small holes in the bucket, the water will come out at a certain rate. Add a fifth hole the same size, and you're supplying more water (increasing the current and therefore making the servos stronger AND faster); however, the bucket empties 25% sooner than when it only had four holes.
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Old 04-23-2010, 10:23 PM   #8 (permalink)
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Quote:
Originally Posted by hahahell View Post
Is there anything I can do? What's the purpose of having all servos being able to to handle 8.4 if your receiver can't?
You power your servo directly on 8.4VDC, and step down or regulated 5~6VDC for your receiver. The receiver will put out pulses at its power level, but this should be plenty for the servos to pick up. You can make a little "power bus" adapter that goes between the servos and receiver for this purpose.

The same arrangement is necessary between many gyros and their tail servo, this is just a larger application of the concept for cyclic servos.
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