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Discussion
Hitec 9381 any good?
I think the 9380 is the best product in the RC hobby. But, I don't know how these 9381s will be. They have all metal cases, but I haven't had a case go bad or get distorted on my 9380s. They both have the same low current draw. Hitec claims 5x less current than other servos and in my hands on experience for the last two years that is exactly right. Stalled they only draw 2amps whereas other servos draw 5-6amps or more. They advertise constant torque output regardless of load, and I've found that to be true, also. The new servos, the 9381s are said to use a magnetic encoder. As far as I know the 9380s use a potentiometer. We'll have to see what kind of difference that makes, as well. Interesting, though, interesting.
http://www.ni.com/white-paper/4500/en/ https://www.engineersgarage.com/tuto...-potentiometer |
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Potentiometer has continuous resistivity change, but hall sensor base magnetic device has a bit steps in resistivity change.
Interesting to see how 9381will be accurate relative to 9380. I also 100% agreed with what rcfly mentioned about 9380. Technically wise it is the best servo on the market for heavy duty tasks on large planes. |
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Joined Jan 2008
682 Posts
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I will be interested to see if the "magnetic encoder" makes it to retail. Many have tired this including Hitec and dropped it. But someone may get it right some day. I have been waiting for potless servos since 1968. Kind of like jet packs.
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The hall sensor in the JR MPH83T-M2 worked great. That was my favorite servo two years ago, until I found the Hitec 9380. The MPH83T was good, but the 9380 is great.
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I bought a plane full of 9380's based upon Rcfly's recommendation and they are awesome. Extremely strong and very fast.
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Joined Jan 2008
682 Posts
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Joined Jan 2008
682 Posts
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Hitec coreless brushed stall current - 9.8 Amps
Hitec brushless stall current - 2.7 Amps There are no magic motors. How is this achieved other than current limiting at startup - soft start/neutral ? Not that I have anything against soft start. I used to fly Proline servos and liked the feel. How many milliseconds does it take to saturate the field at motor startup/reverse ? Maybe this is a great idea! If you have 12 servos that stall at 9.8 Amps, it is easy to see why plugging them into a 6014/7014 receiver is a bad idea - depending on how much wire is between the RX bus and the 2S LiPo batteries. Suppose you have 6 aileron servos and slam the stick over. |
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The Hitecnology website has a lot of products that will not be available to consumer hobbyists, many of the servo models are strictly for commercial/industrial use only and a number of them will not have PWM frequency control as an option.
Our brushless servos use an extremely unique motor and circuit design- we stuffed a massively oversized motor inside and had a custom circuit designed to control said motor. It is capable of many things, including an incredibly low stall current- these servos can be run at full stall all day long and not burn up. |
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Joined Jan 2008
682 Posts
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OK. We are going with magic motor/controller.
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Nothing magic about it, it's an oversized motor and a unique circuit that work in conjunction- the motor itself is dialed way back in its power output. The motor itself could push almost 1000oz/in of torque, but it's dialed back because neither the gears nor servo case would withstand that kind of force. The circuit itself is smart in how it controls the motor also, and one of the unique features is these servos actually send some power back to the power source, further aiding in their efficiency.
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