Question

Design the automatic door using bjt and pir sensor.
Do it using only Bjt. Don't use arduino and any sort of programmable IC.

Answer 1

PIR sensor detects any motion through its surface and gives the output. It has delay time adjust, sensitivity adjust, ground, VCC, output, and BISS0001 PIR chip. thus the basic circuit looks like this. here in the place of motor we can add any other equipment like buzzer or light and use it for another purpose.

here D1, D2 are the doors.

another circuit where in the place of motor-driven doors, we can use a relay circuit for closing and opening. the circuit as shown.