how to make 4v battery charger

how to make 4v battery charger hi friends in this video i have made a 4v battery charger it is made using common and easily available components. It has auto cutoff feature which protect your battery from being over charged. I hope this video will be helpful to you please like share and subscribe. Components: 1- 1X BD139 transistor 2- 1XBC557 transistor 3- 2X BC547 transistors 4- 2X 100 ohm resistors (1/4 watt) 5- 4X 10K ohm resistors (1/4 watt) 6- 1X 1N4007 diode 7- 1X 10K variable resistor 8- 1X red led 9- 1X blue led 10- 1X 100uf 50V capacitors (electrolytic) 11- 1X 5mm dc female jack 12- vero board 13- jumper wires 14- 6V power supply Circuit diagram: https://drive.google.com/open?id=1OLB... https://drive.google.com/open?id=12bd... previous videos:    • How to Make 12V Battery Charger