aeclark@watyew.waterloo.edu (Robert Fridrich) (12/15/89)
Hi there. Being fairly new to electronics I figured I would run some of my ideas though this news group before attempting this project. ANY input would be appreciated. I have just bought a protable top o'the line Sony tape/radio/cd player, and I was thinking about attempting the following: -Installing rechargable batteries (permenently) into the unit and have them self recharge when the unit is pluged in. And also install a charge meter to tell me when the batteries are running out. Problem: Is this a good idea? Would it be better to have a different jack for the recharging? When recharging how would I regulate the input volatge into the unit, or should I have a recharge mode and a play mode separate from one another. -I would also like to install audio jacks so that I could hook up my VCR to the speakers. Is this a non-trivial thing to do? -A cable input would also be nice, to get those hard to hear radio stations. Has anyone out there tried these, and if so any advice would be helpful. Also, does anyone have some ideas of their own that I could try on my unit. Thanks in advance. Robert Fridrich.. -- Robert Fridrich "E' molto pericoloso, signorina." aeclark@watyew used by permission "Oh speak it, SPEAK IT!!" from Alexa E. Clark, the babe.
jgk@osc.COM (Joe Keane) (12/23/89)
In article <19307@watdragon.waterloo.edu> aeclark@watyew.waterloo.edu (Robert Fridrich) writes: >I have just bought a protable top o'the line Sony tape/radio/cd >player, and I was thinking about attempting the following: > -Installing rechargable batteries (permenently) into the unit > and have them self recharge when the unit is pluged in. And > also install a charge meter to tell me when the batteries are > running out. > Problem: Is this a good idea? Would it be better to have a > different jack for the recharging? When recharging how would > I regulate the input volatge into the unit, or should I have a > recharge mode and a play mode separate from one another. It's easy to use a standard three-terminal regulator to supply constant charging current. The main problem is voltage drop. The input voltage has to be higher than the battery charging voltage by the drop through the charging regulator; this voltage has to be higher than the battery nominal voltage, which is higher than the voltage you'll get out of it when it's running down, which has to be higher than the final voltage by at least the drop through the main regulator. These drops could easily add up to five volts or more. Another possibility is to build a switching current supply to recharge the battery from a lower input voltage. This is a complicated circuit but it's not actually as hard as it sounds. There are chips which do most of the work for you; just tack on a coil and other random parts. Besides, you'll learn a lot about neat stuff.