This is a follow-up to my prior post about a DIY DC to DC power supply for my FujiFilm S100fs camera. I recently purchased a Pentax K-5 which I hope to use for time lapse work. After doing some testing I found that the internal battery in the K-5 will power the camera for 3 hours and was capable of taking more than 10,000 6MP stills in continuous shooting mode. However for longer term shooting, a DC power source is necessary.
The K-5 provides a strange DC-IN port labeled 8.3vdc. This is the same port used on several of the K-series cameras and would normally be connected to Pentax’s D-AC50 AC power adapter. But this would require me having an DC to AC inverter to power the AC to DC adapter. This DC to AC to DC conversion would be very inefficient, requiring 5x the battery capacity. So I built a similar DC to DC converter based on Dimension Engineering’s SWADJ-3 and D-SWADJ switching regulators.