Thank you Lefty, I think I got it with the power supply!
Charging is still a "black magic" for me, but I'm really interested on it after reading this
https://en.wikipedia.org/wiki/Recharging_alkaline_batteries
This circuit seems to be adecuate, but relies on led colors and other variables so I don't like it too much
https://digilander.libero.it/bubblegate/ecircuit3.html
Sorry by the avalanche of noob questions that follows:
Can I simply use a LM317 variable regulator, to select a charging voltage until I read 100 mA on my Amperemeter?
**broken link removed**
Or what about a resistor on series, as I said?
V = I * R
V/I = R
If my battery is 1.5 volt - 100 mA ----> 1.5 / 0.100 = 15 ohm?
If this is correct, what should be the charging voltage, 1.5 volts?
So a 1500 mA battery coild take 15 hours charging?
Edit: To make the charger pulses, I'll use a 555 driving a transistor