Esc with seperate bec - RC Groups
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Dec 30, 2012, 06:56 AM

Esc with seperate bec

I have just bought a second hand FunCub and it came with an ESC with a seperate BEC which is powered from the ESC Battery input. The BEC has a normal servo plug OUT with just black and red wires connected
I intend to use a Hitec Optic 5 TX with a Minima 6T 6 Channel RX.
My question is which channel do I connect the BEC Servo B/R output to on the Minima RX. The 6th channel is marked "chan6 Batt" and it would seem that I should use that one. But being a bit of a newbie I just wanted to make sure I do not end up with a smoking RX.
I will not have any spare channels on the receiver other than 6, although I will not be using flaps I will have Elev, Airlons, Rudder, Throttle and an Eagle Tree Stabilizer mode switch connected to channel 5.

The Throttle servo cable does have b/r/and white connected which I do not quite understand as it seems to me that power for the receiver is also available on that channel . All in all just a bit confused. Any Advise would be appreciated.

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Dec 30, 2012, 08:54 AM
An itch?. Scratch build.
eflightray's Avatar
If the ESC does not actually have BEC, (often referred to as an 'Opto' ESC), then a separate BEC or 4.8v supply, (4cell nimh etc), has to be used.

On all Rx's the +ive's are all connected together, same with all the -ive's, (at least to the best of my knowledge). So the supply to the Rx can be plugged into any spare channel, or even into any used channel via a 'Y' lead.

The ESC always has to be plugged into the 'throttle' channel.

If an ESC did have BEC, but wasn't powerful enough for the number of servos, a separate BEC can be used. BUT, the ESC's BEC should be disabled by removing the center terminal from the connector and insulating it, (red lead).
Dec 30, 2012, 09:24 AM
Thanks for that I think I understand:

The ESC in the FunCub has r/b/w servo connections but it might not have a BEC in which case it will not power the receiver anyway so the sepertate bec is used and plugged into a spare channel which I assume is "ch6 batt" I suppose it would be easy to connect the system up without the BEC servo plug. If I got power to the receiver then the ESC has a built in BEC. If I get no power to the receiver then I must use the seperate BEC. I would then have 2 choices of connection:
1. with seperate BEC or
2. without seperate BEC

But NOT internal BEC and external BEC together ie disconnect the red wire on the ESC throttle?

Am I correct in the above ?

Thanks again

Dec 30, 2012, 10:29 AM
An itch?. Scratch build.
eflightray's Avatar
Yes, use one or the other is the safer way to go.

Usually the ESC manufacturers label will state if it has BEC, and what current rating the BEC is.
Dec 30, 2012, 11:24 AM
Thanks a lot.
Tried power up without the BEC connected and RX was dead. I have no detail on the ESC also no name on the case but it looks "big". Anyway all connected and working now with the extrernal BEC thanks for the help good info for the future.Just got the eagle tree stabiliser to install now but thats another story. Thought the stabiliser may give me a fighting chance of putting the FunCub up and bringing it back in one piece until I gain some confidence and practice. Had 12 months now with a hawksky but I am expecting this will be a totally different flying experience


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