please ignore the lamp and 220vAC supply when i use 12v DC insted of 5v and changed relay to 12v the circuit doesnt work how to use the circuit and modify it to work for 12v. i need to connect and disconnect 2 points(for controlling my 3d printer on and off)
edit:I have connected the circuit exactly like the circuit i have given (i dont really know to use any software to make the circuit so i havent put my original one but its the same!) changes i made to this circuit 1. changed 5VDC supply to 12VDC supply 2. changed 5VDC relay to 12VDC relay switched on the supply and relay is always ON i.e the relay gets 12V even if i remove the transistor
so my question is will this circuit actually work? Can it be made to work for 12VDC supply with 12VDC relay? IF this transistor as switch doesnt work then can anyone suggest a better circuit? How to calculate the base resistor value?
edit2: i had a bad transistor so now i checked the transistor before using it note: i used hfe as 75 is that correct value for using 12v source? how to determine that value from datasheet from the graph