asa!!
Newbie level 1
hi.please help.i have a circuit consisted of a white led and a resistor of 0,12KOhm.the voltage offered to the circuit is around 15v.i want to adjust to that circuit a transistor to work as a switch.i have bought a 2N3904 transistor.the current i want to have to the led is 125mA.i assumed that the beta value of the transistor is around 100.so the base current should be 1,25mA.
Without being sure , i beleive that the base needs a voltage of around 0,7V to work as a switch meaning to go from the cut of area to the saturation area.i have adjusted a resistor to the base of a value of 5,6KOhmso i figured that i need a voltage of 7v=0,7v=7.7v at the base in order for the transistor to work as a switch.
problem is it does not work.what is wrong?please help
Without being sure , i beleive that the base needs a voltage of around 0,7V to work as a switch meaning to go from the cut of area to the saturation area.i have adjusted a resistor to the base of a value of 5,6KOhmso i figured that i need a voltage of 7v=0,7v=7.7v at the base in order for the transistor to work as a switch.
problem is it does not work.what is wrong?please help