An Arduino can be used to test the life of any battery with less than 5 volts, Boxall says. So, for a quick way to see how much juice your AAA, AA, C, or D batteries have left, build this ...

Making a servo tester using an Attiny85 micro chip, Attiny45 also works for this project. This diy servo tester is as good as any other servo tester, the difference is that it can be programmed to do ...