The Eachine VR D2 goggles are a nice bit of kit, but the there are currently two things that bother me with it currently:

• Black frames when too much static occurs in the recordings, does not happen on the live feed though so for flying it is no problem.
• No sound recording. It is marked as an option in the settings of the DVR to enable sound recording, but the audio is not physically connected.

The first problem will hopefully be corrected in a future firmware update by Eachine. The latter can be solved with a few components and a bit of soldering. This modification only takes the audio from one of the receiving channels so it does not abide the diversity aspects of the video receiver.

Audio signal

Both receiver modules provide an audio channel on the third pin from the right. The audio has a DC offset and it has quite high output level for my liking. I came up with a tiny circuit to remove the DC offset and to be able to adjust audio level to my liking.

The values I use for the pot and the capacitor are not critical. I used a trimmer pot because I have no intention to adjust it every recording so it can be all tucked inside without brutalising the housing.

On the DVR connect the audio signal on the 5th pin on the middle connector. The DVR looks to be closely related to the ProDVR device so I use the pinout on the Banggood website as a reference.

(Middle connector, pin 5 is audio in on the DVR module)

To secure the modification I applied copious amounts of hotglue to secure it all in place.

Future improvements

Add diversity support. With an analog multiplexer such as a 4051 it should be possible to implement audio diversity following the video channel. Both receiver audio outputs connect to a seperate 4051 input and the resulting output should be routed to the DVR audio input. Control lines switching the video on the original PCB could be extended to control the audio MUX as well.