View Full Version : mcpx board in trex 250
02-26-2012, 07:51 PM
From the thread I've read, anyone tried to install 3in1 on a 250 class heli. In the diagram above that I made, is the wiring correct? I do not understand how to reduce the voltage from 11.1V to 3.7V (mcpx-board) ? See in the image above, the position of a black box with a question mark.
02-27-2012, 09:43 PM
I love the mcpx but the only reason for to use it as a flybarless controller is becuase it's so small. The tarot zyx flybarless unit is cheaper and from what I've read and seen videos of will perform way better. That is the best cost effective option on for a 250 or any similar sized heli.
If you were just trying to experiment I think your idea is cool but I see guys with good flybarless units piro-ing and staying in place and when I piro on my mcpx it heads toward the ground. :)
02-28-2012, 03:11 AM
Hi, There is a good thread on RCGroups somewhere with a guy doing just this on a 450 clone, well worth a search as he's gone through all the pain already
Where you have your "?", you have the 2 power wires coming out of any spare port on the RX, this will be at the voltage that your ESC's BEC puts out, typically somewhere between 5 and 6 volts - you need to measure this to be sure
As the BEC output is regulated and the voltage requirement to the MCPX board is say 3.8 - 4.2 volts, then I understand that the most commonly used solution is to use a couple of silicon diodes in series
A standard silicon diode typically drops 0.6v across it's terminals, the number that you require depends on the actual voltage that your BEC is putting out