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Futaba receivers and Diamond D 4.7 servos

Old 07-23-2008, 05:30 PM
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rcmark
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Default Futaba receivers and Diamond D 4.7 servos

I have Futaba R617FS and a Futaba R617FS receivers and am running Diamond D 4.7 servos. I want to run the servos directly off my two cell lipo pack. I connect the signal wire to the receiver and the red and black power connectors to the battery. The servos will not work! What am I doing wrong or will this setup just not work with Futaba receivers?
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Old 07-23-2008, 05:35 PM
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SkunkyMagoo
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Well for one...you just fried your servos by pumping 7.4V into them. Next you want to look into what is called a BEC which will power your servos directly from the pack while regulating the voltage.

Castle creations, Sport BEC, uBEC, etc.

EDIT:

Although I have been reading they take up to 9.6v? WOW that is a lot for such a small servo! I hope that it is a lot faster than .14 at that voltage...if it can in fact take that anyways...I have my doubts.
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Old 07-23-2008, 05:50 PM
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Originally Posted by SkunkyMagoo View Post
Well for one...you just fried your servos by pumping 7.4V into them. Next you want to look into what is called a BEC which will power your servos directly from the pack while regulating the voltage.

Castle creations, Sport BEC, uBEC, etc.
Wrong !! Diamonds will take 7.4V !!
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Old 07-23-2008, 05:58 PM
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2S Lipo (2-cell Lipo in series; 7.5-8.4 volts) is also not good for your radio-receiver. Standard voltage for servos and receivers is about 4.8-5 volts (4-cell nicad or nimh). Some "standard" receivers will tolerate 6 volts (5-cell nicad or nimh). A few low-voltage, micro-receivers will work with a 1-cell lipo. Many micro-servos will not tolerate 6 volts (smoke escapes). Whenever you use a 2S or higher-voltage lipo to power the Rx and servos, you will need a separate, voltage-regulator (e.g. the Battery-Eliminator-Circuit in the Electronic-Speed-Control) to power the Rx and servos.
D47 servos will work fine with a Futaba Rx, when the voltage to the Rx and servos is regulated to 5 volts.
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Old 07-23-2008, 06:00 PM
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I think he is powering the RX through is ESC. Which, hopefully, has a BEC internal.
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Old 07-23-2008, 06:13 PM
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http://www.rcgroups.com/forums/showthread.php?t=780986
There ya go!
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Old 07-23-2008, 06:22 PM
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Originally Posted by rcmark View Post
I have Futaba R617FS and a Futaba R617FS receivers and am running Diamond D 4.7 servos. I want to run the servos directly off my two cell lipo pack. I connect the signal wire to the receiver and the red and black power connectors to the battery. The servos will not work! What am I doing wrong or will this setup just not work with Futaba receivers?
Assuming the Rx throttle-channel is properly connected to the BEC-connector from the ESC; and assuming the D47 servo will tolerate 8.4 volts (fully-charged 2S lipo):
You should be able to drive the servo with the 2S lipo by joining the connector to the servo as follows: red wire from servo-connector joins to battery positive (red). Black (brown) wire on servo connector joins to Rx minus-pin. Signal wire on servo connector joins to Rx signal-pin.
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