Thursday, December 28, 2017

Zeta FX-79 Buffalo Build - Wiring plan

Zeta FX-79 Buffalo Build - Wiring plan

The stock configurations for the FX-79 seem to recommend running with 3s lipos, so that's what I'm planning to do.  I'll be using two 5000 mah batteries in parallel.    My Flight Controller is rated up to 5s, as far as I can tell on the forums, so I have the option of upgrading later if I wish.

The Omnibus F4 Pro V2 comes with an onboard 3 amp BEC.  However, as I read the forums, I understand that it can get rather warm.  As a precaution, I'm planning to run very little through the onboard BEC.

Power Plan

  • Direct from batteries
    • Flight controller - rated to 5s (I think).
    • Runcam and VTX (through a filter).  Both are rated up to 6s.
    • ESC (via the Flight Controller for current measuring)
  • BEC on Flight Controller
    • GPS
    • Uart inverter
  • External BEC
    • Servos
    • Receiver
  • External BEC (auxiliary port)
    • Lights or special effects
I roughed out a wire plan on my office whiteboard.

About Club24A

There are known problems with this board with regards to reporting accurate current if VCC is jumpered into the Camera or VTX pins.  It's known as "Club24A" in the forums.  I'm avoiding that problem entirely by not using the onboard jumper to apply power to the RAM pins.  I'm actually hijacking the RAM pins for another purpose (RSSI).  I'm providing the power to the camera and VTX via the wiring harness, apart from the Omnibus board, so I do not expect any of the Club24A issues.

Riser pins

Since I'm providing power to most of the external devices via the external BEC rather than through the FC, it's led to a rather convoluted wiring harness.  While the FC provides 3 pins in most places, for powered servo cables, I'm generally using just the signal wire, and drawing power from my external BEC.  I decided to solder wires directly onto the Flight Controller and terminate with female servo connectors.  This makes the flight controller a bit of a hassle to wire up, but with care, it should be alright. 

I'm planning to use extension cables everywhere, so that the FC can be removed for calibration or reprogramming if necessary.  Also, being the most convoluted part of the build, it should be fairly easy to transplant, if the plane crashes badly enough that I need to replace the foam.

Here's the flight controller wiring, about 3/4 done.  I'll update this picture when it's complete.  Note the heavy cables which lead to the batteries and ESC.  The servo cables patch into other cables to provide power.

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