I needed to send this Nikon compact camera up on a High Altitude balloon to take continueous HD video. However, this Nikon compact from ebay would not record continueously for more that 8 minutes. Once the file size got to 2GB, it stopped. It was a limitation of the FAT file format which limits the video to 2 GB. So I soldered wires to the camera shutter button, tried find out which onces had to be connected to start and stop the video and then connected it to an arduino nano to apply the required voltage to the right pins.
I figured out that connecting 2 of the pins would trigger off the video. One was connected to ground and the other measured at +3V. I used an Arduino nano to generate the +3V by putting the 5v ouput pin through a 2k,3K voltage divider which brought it down to 3V. That triggered off the shutter.
Interestingly, I could power the camera at 5V via the Arduino’s voltage regulator. The battery for the camera is rated for 3.7 V but it is quite happy to work at 5V. However, there seemed to be some sort of current limiter on the arduino that sometimes dropped the voltage.
Warning!! BE very very careful about handing the camera when it is opened. There is usually a fully charged capacitor charged to 180-330 volts that can hurt. Trust me. I got shocked by them. On the nikon, there were 2 pads marked by a lightning symbol that indicated the live points. You can short them with a wire if needed. Otherwise, it is best to cover those points with tape.
I did create a schematic of the wiring just to make things more organised.
