This is a NiCd/Ni-MH charger that can charge with constant current and automatic charge termination when the total voltage for all cells reach the setting voltage.
I design this project to charge for 4 cells Ni-Cd/Ni-MH only .After assembly all components into PCB then adjust VR1 to get the voltage at pin 5 of LM555 is 5.8-5.9V or about 1.45 V/cell (1.45 x 4 = 5.8V)
This circuit charging the battery at about 270 mAh or 10% of C (my battery is sanyo Ni-MH 2700mAh) .You can change the charge current by replace R2. The charge termination when the voltage at pin 6 of LM555(total cells voltage) reach to the voltage of pin 5 of LM555 and the relay1 turn off so no power consumption when charging complete becuase it open the main AC power supply. This project like a general night chager in the market beause it take a long time to complete charging.