03-05-2011, 04:29 PM
This automatic door opener can be made using readily available
components. The electromagnetic relay at the output of this gadget
can be used to control the DC/AC door-opener motor/solenoid of an electromechanical door opener assembly, with slight intervention in its
electrical wiring.A laser diode (LED1) is used here as the light transmitter. Alternatively, you can use any available laser pointer.
The combination of resistor R1 and diode D1 protects the laser diode
from over-current flow. By varying muliturn trimpot VR1, you can adjust
the sensitivity. (Note that ambient light reflections may slightly degrade the
performance of this unit.) Initially, when the laser beam is
falling on photo-transistor T1, it conducts to reverse-bias transistor T3 and
the input to the first gate (N1) of IC1 (CD4001) is low. The high output at
pin 3 of gate N1 forward biases the LED-driver transistor (T4) and the
green standby LED (LED2) lights up continuously. The rest of the circuit
remains in standby state. When someone interrupts the laser beam, photo-transistor T1 stops conducting and transistor T3 becomes
forward-biased. This makes the output of gate N1 go low. Thus LED-driver
transistor T4 becomes reverse-biased and LED2 stops glowing. At the same time, the low output of gate N1 makes the output of N2 high. Instantly, this high level at pin 4 of gate N2 triggers
the monostable multivibrator built
around the remaining two gates of IC1
(N3 and N4). Values of resistor R8 and
capacitor C1 determine the time period
of the monostable. T.K. Hareendran Laser-guided Door Opener s.c. dwivedi
The second monostable built around IC2 (CD4538) is enabled by
the high-going pulse at its input pin 12 through the output of gate N4 of
the first monostable when the laser
beam is interrupted. As a result, relay
RL1 energises and the door-opener
motor starts operating. LED3 glows to
indicate that the door-opener motor is
getting the supply. At the same time,
piezobuzzer PZ1 sounds an alert.
Transistor T5, whose base is connected
to Q output (pin 10) of IC2, is used for
driving the relay. Transistor T6, whose
base is connected to Q output of IC2,
is used for driving the intermittent piezobuzzer.
‘On’ time of relay RL1 can
be adjusted by varying trimpot VR2.
Resistor R9, variable resistor VR2 and
capacitor C3 decide the time period of
the second monostable
Download full report
http://pecworld.zxqAssets/SOURCE/PDF_fun...n09_03.pdf
components. The electromagnetic relay at the output of this gadget
can be used to control the DC/AC door-opener motor/solenoid of an electromechanical door opener assembly, with slight intervention in its
electrical wiring.A laser diode (LED1) is used here as the light transmitter. Alternatively, you can use any available laser pointer.
The combination of resistor R1 and diode D1 protects the laser diode
from over-current flow. By varying muliturn trimpot VR1, you can adjust
the sensitivity. (Note that ambient light reflections may slightly degrade the
performance of this unit.) Initially, when the laser beam is
falling on photo-transistor T1, it conducts to reverse-bias transistor T3 and
the input to the first gate (N1) of IC1 (CD4001) is low. The high output at
pin 3 of gate N1 forward biases the LED-driver transistor (T4) and the
green standby LED (LED2) lights up continuously. The rest of the circuit
remains in standby state. When someone interrupts the laser beam, photo-transistor T1 stops conducting and transistor T3 becomes
forward-biased. This makes the output of gate N1 go low. Thus LED-driver
transistor T4 becomes reverse-biased and LED2 stops glowing. At the same time, the low output of gate N1 makes the output of N2 high. Instantly, this high level at pin 4 of gate N2 triggers
the monostable multivibrator built
around the remaining two gates of IC1
(N3 and N4). Values of resistor R8 and
capacitor C1 determine the time period
of the monostable. T.K. Hareendran Laser-guided Door Opener s.c. dwivedi
The second monostable built around IC2 (CD4538) is enabled by
the high-going pulse at its input pin 12 through the output of gate N4 of
the first monostable when the laser
beam is interrupted. As a result, relay
RL1 energises and the door-opener
motor starts operating. LED3 glows to
indicate that the door-opener motor is
getting the supply. At the same time,
piezobuzzer PZ1 sounds an alert.
Transistor T5, whose base is connected
to Q output (pin 10) of IC2, is used for
driving the relay. Transistor T6, whose
base is connected to Q output of IC2,
is used for driving the intermittent piezobuzzer.
‘On’ time of relay RL1 can
be adjusted by varying trimpot VR2.
Resistor R9, variable resistor VR2 and
capacitor C3 decide the time period of
the second monostable
Download full report
http://pecworld.zxqAssets/SOURCE/PDF_fun...n09_03.pdf
