Projects Trex 450 Pro 3GX HV Servos build

kelleysislander

kelleysislander

New Member
Howdy,

I am wanting to use HV servos for cyclic on a 3GX with a 6V tail servo. How might I approach this? Can I run the unregulated 7.4V straight to the 3GX and run the ESC's BEC output to the tail servo? Has anyone done this? What would the wiring diagram look like?

Thanks,

Bill
 
Tony

Tony

Staff member
What i would do is run whatever voltage you want, up to about 8.4v on the Rx and jsut allow that power to go to the cyclic servos. Then, get a voltage regulator for the tail servo. This is how I would do it anyway.
 
Lee

Lee

Well-Known Member
Which servos are you going for? Are you building a 6S stretched 450? I'm trying to decide which servos to put on my Warp 360.
 
kelleysislander

kelleysislander

New Member
Hi Tony,

Thanks for that plan... Since the Spektrum RX's will handle up up to 9.6V, are you suggesting

A). Running the RX / 3GX on the 7.4V (8.0, whatever you want to call it) and
1. plugging the cyclic servos into the RX / 3GX
2. running the +/- (red/black) 5.0V leads only for the tail servo from the ESC's BEC output
3. Tail servo signal line jumpered straight from the RX

OR

B). Running the RX / 3GX on the ESC's BEC output of, say, 5.0V (or 6.0 if the tail servo can handle it), and
1. running the +/- (red/black) only from the 7.4V to each cyclic servo
2. jumpering the signal line for each cyclic servo from RX / 3GX to each cyclic servo
3. running the tail servo on the ESC's BEC output

I believe that Plan "A" and Plan "B" deliver the same practical effect...

In Plan "B" there is more wiring since we are jumpering each cyclic servo, whereas in Plan "A" we are only jumpering the signal line for the tail servo. In any event the cyclic servos are getting the HV while the tail servo gets BEC-regulated voltage.

What do you think?

Thanks,

Bill
 
Tony

Tony

Staff member
You will plug everything in as you normally would, directly into the Rx/3GX. All of your cyclic servos will be running at whatever voltage your ESC/BEC is putting out since that is what powers the servos and rx. Then, before you plug your tail servo into your gyro, you will want to plug THIS into the servo plug. The drop down will bring your voltage down to 5.2v which I have heard can be used with futaba that states 4,8v only. Hope this helps.
 
kelleysislander

kelleysislander

New Member
Lee,

I'm building a regular Align 450 Pro "3GX" version running on 3S with a Scorpion 2221-6 (3900kv) on a 11T pinion.

Ultimately I may end up scrapping the 7.4V setup and putting something like some nice MKS DS92+ servos @6.0V instead, but for now I have some pretty decent Corona HV servos http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=19961 that I thought I'd try. I got these for fun because I had some Corona DS939MG's in a 450 that were in a crash that fractured the servo arms right off two of them, and they were fine afterwards. I was absolutely astounded that they were still good after getting jerked so hard in the crash. They flew fine until the next crash at which time one of their "9 lives" bit the dust.

Cheers,

Bill

- - - Updated - - -

Tony,

Thanks for that...

I still want to run unregulated HV (7.4V, not 6.0V from the BEC) to my cyclic servos. If I did that I then could simply use my BEC's (set to 5.0V) to run my tail servo. What I'm basically doing is inspired by this:

http://www.beastx.com/showthread.php?1902-BeastX-and-Spektrum-AR7100r-Setup

If you scroll down to the illustration at the bottom and click you'll see the schematic indicate the power leads at 8.4V and the signal leads coming from another source, in this case the BeastX unit which is running at the regulated 5.2V. In my case, just substitute the BeastX for the RX running on the regulated BEC voltage. The tail servo (run from the RX like it is run from the BeastX in the illustration) gets the regulated output voltage and the cyclic servos get the unregulated HV power while their signal comes from the BeastX (my RX in this case).

I came across this idea while researching how I'm going to run my BeastX / AR7100R in the Trex 600 Nitro Pro that'll be ready soon.

Thanks,

Bill
 
coolgabsi

coolgabsi

Super Mod & DEAL KING!
Yeah bill I looked at that, and that is just complicating things for me. I had a 7100 too and was gonna put it on a beast. But when I looked at that, I wasn't gonna mess with my wiring like that and I didn't. That's why you saw in classifieds I sold mine lol ;D and went to a 7200bx .. Just so much cleaner and minimal wiring. :)

You don't need that here in your 450 . At all. :) it'll just complicate setup and cause more pain than is necessary :) :)

I was gonna suggest that same thing as tony too, just couldn't find a link, and tony did :D .. Thanks tony. :)

I actually might have an extra lying around if you want it... That'll keep your wiring clean on the 450.

On the 600 nitro with the 7100r and the beast (if you go with beast) , yes , you will need To follow that page.

Fly safe!! :) have fun!
 
Lee

Lee

Well-Known Member
kelleysislander

kelleysislander

New Member
Hey Lee,

Yep, that's in my HK "Wish List" as well. I first got onto those from a fellow who was selling a 450 with them. I had never heard of them so I looked them up. Once I get a little better and crash less I will "graduate" from Corona's at 8 bucks a pop to better servos.

Cheers,

Bill

- - - Updated - - -

Tony and Gabski,

Thanks for the input, y'all!. Yep, running HV on a 450 and doping that wiring is mostly overkill. As Tony suggested I'm probably gonna run those HV Corona's on 6V and either use this http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=6775 on tail @ 6V, or if that doesn't really work out I may get a "dedicated" tail servo that only likes 4.8V and step it down.

Cheers,

Bill

- - - Updated - - -

Hi Everybody,

Today I got my 3GX in and the first order of biz is to get it upgraded to v3.0 firmware, so I have a question before I even do any research:

Do I need to have the3GX unit installed on a heli to be able to upgrade it, as is the case with the 3G units?

Thanks,

Bill
 
coolgabsi

coolgabsi

Super Mod & DEAL KING!
Awesome bill!!!


Excited to see this puppy in the air soon.

What gyro you planning to go with 3gx? Total G?

My 700 is coming along too. May be we will maiden together :D

Fly safe!! :) have fun!
 
kelleysislander

kelleysislander

New Member
Howdy All,

I got 4 of the https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=33288 servos and right off the bat 2 had what I would consider minor servo play, so I sent those back. When energized the ones with servo play had less play, about .1 to .2 mm at the servo arm end. The ones with no servo play had no play when energized. Since that time I found another US source for that same servo but I had already ordered 10 of them from HK with the strategy of culling them out to get at least 6 "good" ones since their return policy is rather liberal as long as you send products back unused and in the original packaging.

In the US aloft hobbies

http://www.alofthobbies.com/kst-ds215-servo.html

sells them for about $3.50 apiece more than the HK USA warehouse. From researching I have found that the HK servo and the aloft "KST" brand servo are the same. Exact same specs and description and they look exactly alike save for the sticker. I emailed aloft asking about their experience with servo play on these and Wayne from aloft hobbies replied that their experience was very good - all KST servos were nice and tight. Good to hear but I do suspect that they do not test each one they sell.

Further, here are some good links I came across regarding this terrific servo, which apparently are MKS DS95 clones but with better specs:

http://www.helifreak.com/showthread.php?t=472020&page=2

One person posted that the gear sets for the KST servo from aloft are an exact fit for the Turnigy 306's that HK sells:

http://www.helifreak.com/showthread.php?t=462781

Anyways, once I get the 10 in and cull them for the "perfect" ones, and subtracting the $3.50 it will take to ship the "bad" ones back to the HK RMA center in WA state, I am still ahead of what I would have paid from aloft hobbies. I am seriously considering using them for both cyclic and tail on the Pro I am building and the future Pro I have planned.

Cheers,

Bill
 
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