At first, all Maker “val3tra” wanted was an RF-accessible camera, capable of snapping some photos, saving them onto a microSD card, and on occasion, relaying them to a computer via an RF link. Well, the project has now evolved into an open-source device capable of capturing a year-long time-lape videos.
With the idea of leaving the camera “in a nice spot and coming back next year, without worrying about getting power there,” the build first began using a $20 JPEG camera from eBay that was modded for 3.3V, along with a $4 RF module, a megaAVR MCU and some batteries. The camera was 640×480 with each frame only an average of 48kb, while the additional components drew nearly 100 Joules of power per hour.
Since a D-cell has about 60,000 Joules, the Maker estimated that four of them would provide enough run time for about 200 days. As Hackaday’s Brian Benchoff notes, “This build was then improved, bringing the total battery consumption down to about 3.5-4 Joules per frame, or at one frame every 10 minutes, about 24 Joules an hour. That’s impressive, and getting this camera to run longer than a dozen or so months raises some interesting challenges. The self-discharge of the battery must be taken into account, and environmental concerns – especially when leaving this camera to run in a Moscow winter, seen in the video below – are significant.”
Power was supplied from 4.8+ V and over a 3.3V LDO, so four alkaline batteries were ideal. “I thought of using a switching regulator to increase efficiency, but it just isn’t worth it on this scale — at best you can get 20% increase in run time,” val3tra adds.
Now, one frame captures three seconds of footage at 100mA and takes seven seconds at 60mA to jot the picture down. Between frames, the Maker says it stays in deep sleep, consuming 91 uA.