The document describes the working principle of an automatic door light switch. The switch uses bistables inside a CMOS 4013 chip connected in series to store the state of the switch. When the door is opened, flip-flop 2 registers and turns on the light. When the door is closed, the light remains on. Opening the door a second time causes flip-flop 1 to change state, turning off the transistor and relay to switch off the light. The relay is designed to operate between 5 and 15 volts.

1. DISHANT SHARMA

3. It will continue to glow when the door
closed for the first time

4. And when the gate is opened for the
second time , the light will automatically
be switched off

6. The working principle of the light
switch is quite simple. The bistables
inside CMOS 4013 are connected in
series. FF2 is configured as a R-S
memory to store the state of the switch.
S1 must switch as soon as the door
opens that is why it will be mounted on
the door jamb.
When the door will be opened FF2
is registered and its output (pin 13)
will be 1.
This output, connected at the tact
entry of FF1 (pin 3) will open T1 and
activate the relay switching ON the
light.
When the door is closed nothing will
happen because FF2 is unregistered
and its output (pin 13) passes in
state “0″. Only when the door is
opened again, FF1 will change its
state and the output at pin 1 will
block the transistor so the relay will
be disconnected and the door light
switch turns off the lamp.
The relay must operate at voltages
between 5 V and 15 V.

7. Automatic door light
switchLIDS