I have a $40 action camera from Amazon. It’s a bit old, not even listed anymore as I believe it’s been superceded by upgraded versions.
I’ve been using it on my helmet when I ride and I wanted to add an external microphone. On these cheap cameras the firmware is hit or miss if you can use a micro USB to 3.5mm adapter. I found a few YouTube vids and websites where people have taken apart their cheap cam and solder in a 3.5mm jack.
I didn’t find one where they retain the internal mic, they yank it off and put in a jack. Here is how I did it to have both.
Cheap cam
The jack will end up on this side
Not sure if the newer ones will have glue but my cams front and back simply clicks off.
This is the internal mic, with convenient polarity label
Local store had a 5 pin jack (Torrance Electronics rocks)
Pinout
Wiring plan
Using the 5 pin, you can wire the internal mic in so that when an external gets plugged in the circuit opens and then just feeds in the external.
Then the first bump in the road. It’s all so small I couldn’t de-solder like I’m used to being able to
So the mic broke off from the pins.
Amazon’d some 6mm ‘upgrades’ (cause bigger is better? I noticed some of the other action cam hacks we’re simply replacing the internal mic with a larger version)
Now mistake two, I used gorilla gel super glue for the 3.5mm jack. This caused some kind of vapor that
overnight gunked up the PCB, lens, sd card holder etc (it was left out of the case so was well ventilated). I had to use acetone to clean off the lense. And now the SD card does not ‘click’ out, I have to pry it out with a jewlers screwdriver. Also I think it messed up connectivity with the micro USB.
But end result.
Drilled the hole
Test fit
I had a 3.5mm mic for smart phones, that doesn’t work. At first I thought I failed, but I just don’t know much about 3.5mm versions and cross comparability. To test, I took an old headphones wire I had, metered the ground (base) and tip wires, ignoring the two center sections, jumpered one of those Amazon 6mm mics and Bam, works. So just need to use mono 3.5mm mics.
End result, it works. But I’m not confident in reliability because of the gorilla gel glue vapor mess- be it ghost ‘clicks’ of bottons or simply the inconvenience of getting the SD card out.
Hindsight, if I used jb weld for the jack it would be stronger and imo no vapor issue and I would be good to go.
As is, the newer versions on Amazon have a faster 4k fps and external mic support right out of the gate. So I ordered one up and will use this modified one for risky stuff like mounting in the wheel well of my truck when desert running and stuff like that.
Anyhow, wish it went better but was still fun doing the research and jumping into it.