Hello friends I'm new here and want some answers from u. plz help me to sort out the problem related to my circuit of high voltage protection. in this circuit i regulate the dc voltage using zener diode and then output of zener is given to the base of npn transistor. plz check the circuit diagram for detail. now coming to my problem that at second stage where i used transistor as a switch, actually transistor is not working as a switch. the led shown there must be ON/OFF but its nor happen here. when i changed pot value thn intensity of the LED changes only it not goes ON/OFF. can anyone help me regarding this?