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Summary
The purpose of this document is to help you to build Laser Guided Appliance Control. This “Laser Guided Appliance Control” has made to control DC/AC equipments. Thus you can control the various appliances automatically.
The ‘References & Resources’ page has a list of relevant book, website, electronic shop and commonly used part and their prices.
2. Introduction
2.1 What is Laser Guided Appliance Control?
The laser guided control is a device that controls all the equipments by the laser diode or laser pointer when the beam of the laser is interrupted by someone.
2.2 Component used in the circuit
In the circuit following component used
1. Laser Diode
2. Photo transistor L14F1 TI
3. Transistor BC-337, BC-547, BC-557
4. IC1 CD4002, IC2 CD-4538, IC3 LM-7805
5. Other passive component
2.3 Prerequisites:
Knowledge of basic digital and analog electronics.
(A course on Digital Design and Electronic Devices & Circuits would be helpful)
Sheer interest, an innovative brain and perseverance!
3. Overview
3.1 The block diagram
3.2 Architectural Overview
The block diagram will help you to understand the project in the simplest way. In the block diagram the components that are used play vital role for the development and building of the other circuit diagram and different internal architecture view of component successfully.
The other circuit diagram and internal architecture views are also shown one by one carefully and by keeping in mind to show the entire significant components that are used in the project (Laser Guided control) is shown in the next part.
Description and Working
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 light intervention in its electrical wiring.
A laser diode (LLED1) 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 his unit.))Initially, when the laser beam is falling on photo-transistor T1, it con-ducts to reverse-bias transistor T3 and the input to the first gate (N1) of IC1 (CCD4001) is low. The high output at pin 3 of gate N1 forward biases the ED-driver transistor (T4) and the green standby LED (LLED2) 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 ED-driver transistor T4 becomes reverse-biased and LED2 stops glowing. At the same time, the low output of ate N1 makes the output of N2 high. Instantly, this high level at pin 4 of gate 2 triggers the monostable multivibrator built around the remaining two gates of IC1 (N3 and 4).Values of resistor R8 and capacitor C1 determine the time period of the monostable.
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 (pin10) 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 pi-ezobuzzer.‘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 and through it on time of RL1.
The circuit works off 12V DC power supply. Assemble it on a general-purpose PCB. After construction, mount the laser diode and the phototransistors on opposite sides of the doorframe and align them such that the light beam from the laser diode falls on the phototransistor directly. The motor connected to the pole of relay contacts is the one used in electromechanically door-opener assembly. If you want to use a DC motor, replace mains AC connection with a DC power supply.