Like most people, I love taking things apart. Usually I’m foolishly drawn to take things apart in order to reclaim parts for reuse later. However, it can be a chore to find reusable parts, especially in modern consumer electronics. I picked up a broken portable DVD player (GPX PD708B) from the Goodwill outlet store. They price hard goods at $.79 a pound, so usually it’a a cheap way to get stuff like this. Now, I had done this to remove the LCD and attempt to drive it, as a learning exercise for myself. Now, I hadn’t even looked that close at the unit until I brought it home. The first unexpected thing was that it contained a sizable 2000 mAh LiPo battery. That could definiately be re-purposed in a future experiment. As a nice supprise, I found that the charging circuit for the battery, was actually separate from the main board on its own little module. Awesome! Now I not only have a large LiPo battery, but a propery charger/control circuit for it.
It seems to be a complete unit with DC power input, battery power output, managed charging, battery protection, and an empty space to add a charge status LED. It appears to be run off an unmarked (at least I couldn’t see any markings) ATTiny micro. My only clue was the name on the silkscreen was “Lili-new-2Li-TINY13.” A little probing with my meter and scope found that the IC on the right of the board had 5V and ground in the right spots, pin 5 was outputting the “blinky” signal for the LED, and pin 6 was actually spitting out a 32 kHz PWM signal with about 30% duty cycle. See below for my brief examination of the board.
Always nice to actually find something useful.