transistor keeps burning out in the circuit!
hi everyone! i followed this 'ible (https://www.instructables.com/id/Laser-Perimeter-Alarm/) to make a laser burglar alarm for an electronics project. i soldered everything together properly, followed the schematic and all, but every time i connect the battery, the transistor just explodes, like, there's a small spark and next thing you know, its damaged. what can be the reason for this and what can i do to solve this problem? i've already used 4 transistors and all burned out! please help!