I received a contact of a player because of the lack of schema source/charger, so I decided to write a little…
The basic scheme is as follows:
A bit of theory:
This source uses the LM317 voltage regulating, but of course this circuit supports little current (between 0.5 the 3rd depending on model), but using a transistor, in this case I used TiP32 (many others can be used), increases the current in some 1,5 the 3 For each TiP used. In this case I also used a bridge rectifier to avoid return, because the diodes to large chains are much more expensive than the bridge. The other transistor with the zener diode and only serve to force a tension ceiling, so limiting/stopping the load, as the transistor only leads the voltage rising above the zener voltage + (approximately) 0,7 + 0,7 (crash caused by another diode) I have a final voltage maximum 14,4. The two resistances are what regulates the output of the LM, to know the value (for other output values) see this calculator: http://www.electronics-lab.com/articles/LM317/
You can connect as many TiP ’ s are precise to have more current or choose another transistor that supports more current, for me it was easier to use this because had at home and work well.
A note: The TiP32 will warm enough, so you might want to use a sink.