I have a case for my portable dvd player that has attached speakers. They run on a single 9 volt battery. How can I wire an AC adapter to the case so I can use a cord instead of batteries(which only last about 3 or 4 movies)?
Eh Greggo,
Siliconchip did a project a while ago that uses two AA nimh batteries to output 9 volts and with AA batteries at 2300mapms they last a heap longer than 9 volt batteries. The kit only costs $10 australian and I have one that I use for powering a pic project. Altronics and jaycar sell the kit so check it out and it should be good enough but that depends on the current comsuption on your dvd.
Yea Tansis Lithium cells are the go, especially the ones out of old laptop batteries. I've arranged two lithium cells in parrallel to power a 12 lumen 8 mm white led as a nite light and I only need to bring it in once a week for a charge. But size will be a factor for a dvd player though, the best source is laptop battreies that gave up the ghost but usually only 1 or 2 cells go south and the rest are fine.
Be real careful about the polarity of a 9v battery connector. The source and load connections are identical but mirrors of each other; the side which is + on the source is - on the load. The guy who made up that scheme should be beaten severely. I remember how when I was little I thought plugging two 9v batteries into each other to make an 18v dead short was the coolest thing.