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-   -   FP S128 Voltage Limit (https://www.rcuniverse.com/forum/futaba-radios-direct-support-forum-125/9829477-fp-s128-voltage-limit.html)

RCPtero 06-27-2010 08:00 AM

FP S128 Voltage Limit
Hi! I'm assembling an Ultra Stick 40 ARF. I'm planing on using a switching BEC to supply the RX with 6.0v. I have an old Futaba FP S128 servo I was looking to use on the throttle. Can I drive the S128 at 6.0v? Or do I need to drop it down to 4.8v? I've looked on the web, but can't seem to find any specs that speak to the voltage requirements for this servo.


Krysta 06-28-2010 09:00 AM

RE: FP S128 Voltage Limit
The S128 servo will be fine at 6 volts as long as it's regulated.

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RCPtero 06-28-2010 06:01 PM

RE: FP S128 Voltage Limit
Thanks much!!

Creative RC 09-09-2021 05:00 AM

I know this is old, but I bought a plane that has 3 of these old FP-S128 servos and was wondering whether they could run on 6.0 volts. The fellow I bought it from had just recently installed a UBEC and set it at 6 volts. They seem to be working fine.

I found an instruction manual online for the Futaba FP-2GS transmitter which comes with two of these servos. See photo below.

The servo specs say the power requirements are 4.8V - 6V. Since it mentions current drain at 6.0V, I assume the torque of 48.7 oz-in and the speed of .24 sec/60 degrees are also at 6.0V, although it does not specifically state that.


FUTABA-RC 09-09-2021 06:48 AM

That servo as stated above in this tread are fine on 6 volts as long as it is regulated voltage. The speed and torque shown are at 4.8 volts. Both will be faster/higher at 6 volts, but not hugely faster/higher.

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