most of the chargers I own don't work fast enough - they take in the order of 14 hours so I thought "why not make one" since I have about 30 things with chargeable 9 volt batteries in them it would be nice to make a few of these. Anyway I wanted to make one that automatically cut off but it got a bit messy so I figured I would just drop the amount of current going into the battery so I could just leave it going for a few hours.
to work out charge time: hours = mAh / mA
example case: a 9v battery I have is rated at 150mAh
150 \ 50 = 3
therefore 3 hours
the LED illuminates when the battery is connected
the Transistor (BD135) needs to be heatsinked but the LM317 doesn't so if you're using a metal case you could just screw the transistor to the case and use that as the heatsink
