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Presentation door knock
This document describes the fabrication of a printed circuit board (PCB) and prototyping of a door-knock or vibration alarm circuit. It includes a list of components used - PCB, LED, diode, resistor, transistor, IC LM324. It provides the circuit schematic, board layout designed using EAGLE software, and the chemical etching process. It then describes how the circuit works using the quad op-amp LM324 as an amplifier, with a buzzer as the input sensor and transistors to drive the output buzzer or relay. Adjusting the reference voltage with a potentiometer controls sensitivity.
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Presentation door knock
- 1. FABRICATION OF PCBAND PROTOTYPING PRESENTED BY :- B. Vamsi Krishna Door-Knock or Vibration Alarm
- 2. Contents Introduction Components Circuit Schematic Board Layout Process Description of Components Circuit & Working
- 3. Introduction : DoorKnock Alarm This is a simple circuit that activates an alarm when there is a knock on the door or there are any vibrations due to movement of heavy goods or furniture. The circuit uses readily available components.
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- 5. Printed Circuit Board:- A printed circuit board (PCB) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from copper sheets laminated onto a non- conductive substrate. PCBs can be single sided (one copper layer), double sided (two copper layers) or multi-layer (outer and inner layers). Multi-layer PCBs allow for much higher component density. Advanced PCBs may contain components - capacitors, resistors or active devices - embedded in the substrate.
- 6. LED A light-emittingdiode (LED) is a two-lead semiconductor light source. It is a p–n junction diode, which emits light when activated. When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons.
- 7. Diode 1N4007 Adiode is a specialized electronic component with two electrodes called the anode and the cathode. Most diodes are made with semiconductor materials such as silicon, germanium, or selenium.The 1N4007 is a family of popular 1.0 A (ampere) general purpose silicon rectifier diodes commonly used in AC adapters for common household appliances.
- 8. Resistor A resistoris a passive two-terminal electrical component that implements electrical resistance as a circuit element. Resistors act to reduce current flow, and at the same time act to lower voltage levels within circuits. In electronic circuits, resistors are used to limit current flow, to adjust signal levels, bias active elements, and terminate transmission lines among other uses
- 9. Transistor: - Atransistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. BC547 is mainly used for amplification and switching purposes. It has a maximum current gain of 800. Its equivalent transistors are BC548 and BC549.
- 10. IC LM324 Description LM324 is a 14pin IC consisting of four independent operational amplifiers (op-amps) compensated in a single package. Op-amps are high gain electronic voltage amplifier with differential input and, usually, a single-ended output. The output voltage is many times higher than the voltage difference between input terminals of an op-amp. These op-amps are operated by a single power supply LM324 and need for a dual supply is eliminated. They can be used as amplifiers, comparators, oscillators, rectifiers etc. The conventional op-amp applications can be more easily implemented with LM324.
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- 13. Process • Using EAGLESoftwareCircuit Schematic •Using EAGLE Software Board Layout •Using Photo glossy paper Print Out •Chemical Solution Fe2Cl3 Etching Process •Prototype DesignComponents Fabrication
- 14. Circuit And Working The circuit is built around quad-opamp LM324 (IC1), which is configured in amplifier mode. It uses buzzer as the input sensor, two transistors BC547 (T1 through T2), a buzzer and some other components for the alarm circuit. The reference voltage at pin 3 of IC1 is set by trimming potentiometer VR1. The buzzer element plate is fixed at the center of the door. Apply a small quantity of adhesive on the edges between the plates. Wires from the buzzer are connected at CON2. These generate an input pulse when vibrations are caused by knocking on the door. The pulse is amplified by op-amp A1 of IC1. Remaining three op-amps of quad IC LM324 are not used here.
- 15. Cont… The outputof A1 of LM324 from pin 1 is further amplified by transistors T1 and T2 to drive the piezo buzzer or relay. Because of the presence of high- value capacitor C5, the buzzer remains active for a few seconds. The circuit is powered by 9V/12V power supply. Sensitivity of the circuit can be adjusted by 1M potmeter VR1.
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