jamesfarrell

Here's what I have

HPI Savage Flux HP. I'm replacing the stock system with a Spectrum DX3C with has the SR300 receiver that can handle 9.6 Volts.
I have this servo, a JR 8911

http://www.amainhobbies.com/product_...FdKd4AodhmsARw

I have the stock flux system, ESC and Motor. I have a castle External BEC. The servo is capable of 7.4 Volts.

So a guy on another forum said this diagram would work. What do you think?

SyCo_VeNoM

no it won't (well might but could cause issues)

you will need the ground(black wire) off the servo to connect to the BEC, and RX. If its not the servo has nothing to associate with ground for the signal and it could be detected as anything.


PERSONALLY I'd just disconnect the red wire that goes to channel 2, and plug the BEC into the BATT spot, and the servo like you normally would into channel 1

phmaximus

I agree, back out the red and black wires from the connector from the ESC, (ie disable the ESC BEC)

Then plug the red and black output wires from the EBEC into the connector from the ESC that u just removed the 2 wires from..

All u need is a pin to back the wires out of the connectors, just lift the plastic tab and they will slide right out.

Foxy

As Syco said, just take out the red pin from the esc plug and tape it back, so it doesn't go in the receiver. Attach the battery to the bec, and the bec to channel 3/Battery on the RX.

phmaximus

Ahhh but if u do it my way u have 2 power sources to run fans from
The batt plug on the receiver 7.4v
And the ESC's BEC 6v

One of my cars was like That because I had a 2s lipo capable fan on the ESC and only a 6v on the motor.
Either way works, all depends is u want 2 ready to go power spare sources or none

jamesfarrell

I'm confused guys. I don't need any more fans or anything else. I have the fan on top of the ESC, I want that to still work.

So is the rest of the diagram correct? All I want to do is provide 7.4V to my high voltage servo.

So is the diagram correct? But just remove the red (+) wire from the ESC> RX?

SyCo_VeNoM

you need the black wires for common ground all black wires NEED to be tied together somehow(through the RX). I've done this a few times wit my tamiya ESC's that like to pump 8.4V's into the RX. If you don't like I said the electronics will have no idea *** the signal is, and should be without reference.

If you want to do it in a way that you had pictured I modified it properly

to make things easier and neater I'd use a Y-adapter, and just cut the red wire off the end you plug into the RX


but like I said if your RX can take 9.4 volts then you can do it the other easier, neater way which as foxy said just pop the pin out of the plug that goes to the second channel from the ESC cover it with tape, and plug the BEC into BATT or chan 3 with the servo as normal into channel 1.


BTW your original picture technically should work, but without knowing how the companies designed the circuitry unless you take a multi meter and do a continuity check between the black wire that goes to the battery, and the black wire on the plug's black wire that comes off the bec side there is no way to know if they are truly straight connected to the ground. Why I just like to play it more safe then sorry cause if they are not you can add interference to the signal.

phmaximus

I disagree, It does not matter where its grounded, the top wiring diagram will work, its ground through the battery.'
well every thing is grounded to the battery,

there is absoultly no advantage from grounding the servo to the receiver. its allready grounded on a seperate loop to the battery and so is the receiver

im open to the idea, but can u explaine it to me in heapes more detail? to me it just makes no sence.


I still like my way more, is there something wrong with it? and with that way u dont have to buy any extra connectors.
(back out the power wires from the ESC and tape them up, and replace them with the UBEC out put wires, cant get any eaiser than that and u even end up with a spare connector)

phmaximus

This is the how one of my cars was done. So I know it works.

this is a more complex one that i made for lights and a sero that can draw more amps that the ESC's BEC could supply on but its the same thing.

****NOTE, there is a mistake in this one, The ESC's BEC has not been disconected from the receiver just ignore that part lol

SyCo_VeNoM

note I said with how its designed without checking.
Believe it or not I've seen step down convertors that didn't share a common ground in stuff I've worked on.

Simplest way is similar to how you done it just back out the red wire on the ESC, tape the end up, and put the BEC into port 3 or the BATT slot. (how I run my TEU104BK's, and was said by foxy)
No idea why you have the external BEC going to the 2nd port with the signal wire off the ESC.


BTW I run those same switches in my TT01E, and SCX10 for headlights

savagecommander

running the servo through the BEC gives an advantage. just also connect the black wire from the servo to the rx and your good.

jamesfarrell

Yep, I did all that with a Y connector. The problem is, I'm running 3s x 2 = 6s

I'm hoping I don't have to rewire it. Too much voltage going to the BEC like that you think?

phmaximus

I allways though the black servo wire was a connection to the battery via the receiver via the esc?
I'm just trying to understand this stuff in more detail, but why would u link two sepperate power circuits via a earth?
I mean both EBEC and the ESCBEC are both earthed directly to the battery, so why link the earth after the regulation?

Hang on... Is it because in some setups there is a problem with the recivers signal using a different earth, That is within the overall circuit but on a different feed?

phmaximus

The CC BEC is rated to 6s max
So that's all good, the CC Pro is good for 12s

[link]http://www.castlecreations.com/products/ccbec.html[/link]

phmaximus

Hey SyCo, on those controllers did u worry about stepping the volts town to 5.5v for the controllers power feed?

SyCo_VeNoM

no ones I got the spec sheet said 30V max. The logic voltage is what was limited to 5.5volts, and as I've never cared enough to go dig my oscilloscope out to check what my signal wire puts out as voltage I just hooked it up and hoped for the best
not sure if they are the same exact one, but they look it (http://www.pololu.com/catalog/product/1210 one I got)



Like I said the BEC's should already be grounded properly in the OPs pic, but I've hit some electronics where they weren't, for some stupid reason the designer thought it was best to isolate the - output for some odd reason from the - input.

The reason to link the grounds is to make 100% sure there is one common point for the electronics to gauge the signal level from. In all honestly its just as a backup in this instance to make sure there is a common reference point in case the manufacturer didn't do it right on the ESC's BEC, or the UBEC's didn't. When I was in college and had to bread board similar circuits you could not imagine how much of a difference a common ground made with signals. Like I remember signals without grounds hooked up right being like 2 volts off from what it should have been, and jumping around due to interference.

Now if he wants to take a multimeter and do continuity test from the black wire that goes to the battery, and the black wire on the leads that come off the BEC and make sure they both go straight through then yes his 1st pic would be valid if the are connected.

phmaximus

That's handy to know about those picco switches, cheers heaps, mind u the regulators are cheap as chips from hong kong

That makes sence, I wonder if anyone had had any problems with the modern receivers, ESC, BEC, and servos. And I wonder if some servos are more sensitive to interference? Got any idea of what types of interference they mainly suffer from?

SyCo_VeNoM

it would probably be the signal either not being strong enough to be read, or attenuating causing it to act up.

and yea I know the regulators are cheap just wanted the circuit as simple as possible.

jamesfarrell

So I'm good with the 2 3c batteries?

savagecommander

looks good