I'm trying to build a micro quad based on CJMCU flight controller. It is interfaced with an HC-05 bluetooth module and controlled by EZ GUI on android. For some reason, the output voltage on the 5v serial port is around 3.7v. Whenever the motors start spinning, the voltage drops to below 2.9 hence the bluetooth connection is lost. Kindly help.

there is no 3.7V to 5V voltage regulator on that board... so you won't get 5V on it... the voltage drop is due to the motors drawing current from battery, and it's normal.
You might need to add a 5V step up regulator on it if you need 5V.

(31-Jan-2016, 05:41 PM)fpvmonkey Wrote: there is no 3.7V to 5V voltage regulator on that board... so you won't get 5V on it... the voltage drop is due to the motors drawing current from battery, and it's normal.
You might need to add a 5V step up regulator on it if you need 5V.

There is a 5v serial pin on the board. The board uses a 3.7v lipo then it is not possible to have a 5v output pin without a regulator. While desoldering berg stips I kind of damaged C18 capacitor, I just hope it's not because of that. (I got it replaced but not sure if they put the right one!)

There are also some latency issues with the gyroscope.

Try to get bare HC-05/06 bluetooth module, without 5v-3.3V motherboard, it works on 3.3v so you can use 3.3v output of the cjmcu board, it looks like this