Since I first made my arduino intervalometer two years ago, I have used it several times and come to the conclusion that I could make a few improvements to it. The first change I wanted to make had to do with powering the unit. The original design allowed for an external power source and while this allowed for maximum flexibility, it also made the device somewhat unwieldy. Whenever I wanted to setup for a timelapse shot I had to not only bring the intervalometer but also a mintyboost or other power source as well as a power cable. The other major change I wanted to make was to reprogram the timing ranges to something more useful.
In order to power the unit I could have simply placed a mintyboost inside the intervalometer and changed the wiring accordingly, however, I did not want to have to open the device to change batteries. To get around this and still be able to provide the 5V power I needed I decided to use a lithium polymer rechargable battery. This requires both a charging circuit and a voltage booster to convert the battery’s 3.7V to 5V. Luckily Sparkfun Electronics makes just a device that charges the battery via a micro-USB port and is also very compact. Since the intervalometer draws only 28mA while running I chose a 1000mAh battery which not only fits inside the case it should also power the device for over 30 hours, more than enough for a typical timelapse session. Now I have a completely self contained, rechargable intervalometer.
For timing ranges I changed the low range to 1-60 seconds in 1 second steps and the high range to 5-300 seconds in 5 second steps. I think this should end up being much more useful since most of the timing intervals I have used are under a minute in duration and having the capability to more finely tune that interval will be very handy.