STEP DEVELOPMENT FOR THE HARDWARE

STEP 1: Iron at PCB Board

STEP 2: Etching the PCB Board

STEP 3: After etching PCB Board, those boards have to be in clean with thinner

STEP 4: Drill PCB Board 

STEP 5: Solder the component

SCHEMATIC AND CIRCUIT LAYOUT

SCHEMATIC CIRCUIT 

PCB LAYOUT

RELAY OPERATION

     When no voltage is applied to Pin 1, there is no current flow through the coil. No current means no magnetic field is developed, and the switch is open. When voltage is supplied to Pin 1, current flow though the coil creates the magnetic field needed to close the switch allowing continuity between Pins 2 and 4.

Relay Operation

     Each set of contacts can be in one of two states: either “closed” meaning the contacts are touching and electricity can flow between them, or “open” meaning the contacts are separated and non conducting. 

Relay Operation NO & NC

NOTE: http://www.autoshop101.com/forms/hweb2.pdf

CIRCUIT OPERATION OF RELAY

     Single Pole Double Throw (SPDT) – This type of a relay has a total of five terminals. Out f these two are the coil terminals. A common terminal is also included which connects to either of two others.

     The output of each PIC pin is 5V with max output current of 20mA or 0V with 0mA output. The voltage is not enough to run high power device e.g. motor, solenoid. Thus we need a relay to control these high power items. A simple switching circuit (using NPN transistor, C9013) will be used to energize / de-energize the input coil of the relay.

     The relay output is single pole double throw (SPDT). And its coil can be energized using 5V and de-energized using 0V. Normally the relay output NC and COM will be connected. When the input coil of relay is energized, output NO and COM will connect. The switching can be used to control item which is less than 250Vac and 10A.

     A reverse diode (1N4007) is connected with input of relay to avoid reverse spike or over current flow back from the load. And a LED indicator is used to show relay is now On / Off. When relay is On, LED is On. When relay is Off, LED is off. 

Circuit for Controlling an AC or other High-Current Device from a Microcontroller by Using a Relay

RELAY

Relay and Configuration of Relay

     A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism. In electronic, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts. 

LED (LIGHT EMITTING DIODE)

LED and Configuration of LED

     The operation of LED is similar to diode which has two terminals, anode and cathode. In the standard form, the long terminal represent anode and the short terminal represent cathode. . One of the legs with flag must be connected to ground and the other must be connected to 5 volt. LED exit in many form of colors. A normal LED use 5V and 5mA to operate. And through LED the current status of the system can be known. A 1KΩ resistor is connected series with the LED to limit the current pass through LED is 5mA. 

BUZZER

Buzzer

     Buzzer is the devices are output transducers converting electrical energy to sound. They contain an internal oscillator to produce the sound which is set at about 400Hz for buzzers. Buzzers have a voltage rating but it is only approximate, for example 6V and 12V buzzers can be used with a 9V supply. Their typical current is about 25mA. Buzzers must be connected the right way round, their red lead is positive (+).The buzzer used in the project is 5V buzzer. It is direct connected to PIC. Whenever invalid entry detected the buzzer will turn on. Else it remains off. 

PUSH BUTTON

     In this project, the push buttons are connected to 5V when no pressed. Thus PIC gets 1 when button no pressed. Whenever button is pressed the PIC pin is shorted to ground and thus PIC get 0.

Types of Push Button and Description

VOLTAGE REGULATOR

     The voltage regulator module is used to protect PIC and other connected sensors / actuators from over voltage. This is because PIC and all other connected sensors, actuators all support 5V DC only. Over voltage will cause any of the module burn.
     LM7805 is used to regulate voltage in the system and output 5V DC (max output current: 1000mA). It supports input voltage from 7V DC to 18V DC. If the input voltage is over, the LM7805 will burn or auto shutdown due to overheat.
     The generated 5V from LM7805 will be noise filtered by 0.1uF ceramic capacitor and a 1000uF electrolytic capacitor. This is to avoid high frequency oscillation on the outputs which may cause system hang or unstable.
     A diode is connected at the input of the LM7805. This is to avoid voltage connected reversely. An on/off switch is used to turn on/off the system and a LED (5V, 5mA) is used to indicate the system is power on/off. The LED is connected through 1KR resistor to limit current pass through LED is 5mA. 

Voltage Regulator

NOTE:   http://www.fairchildsemi.com/ds/LM/LM7805.pdf

POWER METER

             An electricity meter or energy meter is a device that measures the amount of electric energy consumed by a residence, business, or an electrically powered device. Electricity meters are typically calibrated in billing units, the most common one being the kilowatt hour. A periodic reading of electric meters establishes billing cycles and energy used during a cycle.

An             The KWH Power Meter used in this project is ACE2000 type 292. It is a single phase Power Meter with LCD output to show meter reading. This meter is selected for project because it can give pulse output whenever user uses the meter. The output of the power meter is 1000pulse for each 1KWH. Since the output of the pulse is in 5V for logic 1 and 0V for logic 0. Thus we can direct connect it to PIC microcontroller. The layout of the meter is show below:

Connection of Power Meter

FEATURES + BENEFIT

Key Features		Main Benefits
220-240V 50Hz reference voltage/frequency 1-phase 2-wire network Class 1 or 2 (IEC), Class A or B (MID) accuracy 10A or 20A basic, 100A maximum current Up to 8 switching times for each day type and season giving 160 switching times		Up to six tariff rate registers Maximum Demand for each tariff rate Internal real time clock Display readable without mains power (RWP) Magnetic immunity with magnetic event detection and recording

NOTE:https://www.itron.com/mxca/en/PublishedContent/F14974-4154-ACE2000-Type-292-Brochure-2.pdf

Key Features

Main Benefits

• 220-240V 50Hz reference voltage/frequency
• 1-phase 2-wire network
• Class 1 or 2 (IEC), Class A or B (MID) accuracy
• 10A or 20A basic, 100A maximum current
• Up to 8 switching times for each day type and season giving 160 switching times

• Up to six tariff rate registers
• Maximum Demand for each tariff rate
• Internal real time clock
• Display readable without mains power (RWP)
• Magnetic immunity with magnetic event detection and recording

OPERATION OF BRIDGE RECTIFIER

CURRENT FLOW IN THE BRIDGE RECTIFIER

     For both positive and negative swings of the transformer, there is a forward path through the diode bridge. Both conduction paths cause current to flow in the same direction through the load resistor, accomplishing full-wave rectification.

While one set of diodes is forward biased, the other set is reverse biased and effectively eliminated from the circuit.

CONCLUSION

- Rectifiers also find a use in detection of amplitude modulated radio signals. The signal may be amplified before detection, but if un-amplified, a very low voltage drop diode must be used. When using a rectifier for demodulation the capacitor and load resistance must be carefully matched. Too low a capacitance will result in the high frequency carrier passing to the output and too high will result in the capacitor just charging and staying charged.

TYPES OF RECTIFIER

HALF-WAVE RECTIFICATION

     In half wave rectification, either the positive or negative half of the AC wave is passed, while the other half is blocked. Because only one half of the input waveform reaches the output, it is very inefficient if used for power transfer. Half-wave rectification can be achieved with a single diode in a one-phase supply, or with three diodes in a three-phase supply.

FULL-WAVE RECTIFICATION
     A full-wave rectifier converts the whole of the input waveform to one of constant polarity (positive or negative) at its output. Full-wave rectification converts both polarities of the input waveform to DC (direct current), and is more efficient. However, in a circuit with a non-center tapped transformer, four diodes are required instead of the one needed for half-wave rectification. Four diodes arranged this way are called a diode bridge or bridge rectifier.

     For single-phase AC, if the transformer is center-tapped, then two diodes back-to-back (i.e. anodes-to-anode or cathode-to-cathode) can form a full-wave rectifier. Twice as many windings are required on the transformer secondary to obtain the same output voltage compared to the bridge rectifier above. 

THREE-PHASE AC

     For three-phase AC, six diodes are used. Typically there are three pairs of diodes, each pair, though, is not the same kind of double diode that would be used for a full wave single-phase rectifier. Instead the pairs are in series (anode to cathode). Typically, commercially available double diodes have four terminals so the user can configure them as single-phase split supply use, for half a bridge, or for three-phase use.

     Most devices that generate alternating current (such devices are called alternators) generate three-phase AC. For example, an automobile alternator has six diodes inside it to function as a full-wave rectifier for battery charging applications.

CONCLUSION

- The primary application of rectifiers is to derive DC power from an AC supply. Virtually all electronic devices require DC, so rectifiers find uses inside the power supplies of virtually all electronic equipment.

- Converting DC power from one voltage to another is much more complicated. One method of DC-to-DC conversion first converts power to AC (using a device called an inverter), then use a transformer to change the voltage, and finally rectifies power back to DC.

RECTIFICATION (BRIDGE RECTIFIER)

Various Type of Bridge Rectifier and Diode

-     There are several ways of connecting diodes to make a rectifier to convert AC to DC. Rectifiers may be made of solid state diodes, vacuum tube diodes, mercury arc valves, and other components.

-     A device which performs the opposite function (converting DC to AC) is known as an inverter.

-     The bridge rectifier is the most important and it produces full-wave varying DC. A full-wave rectifier can also be made from just two diodes if a centre-tap transformer is used, but this method is rarely used now that diodes are cheaper. A single diode can be used as a rectifier but it only uses the positive (+) parts of the AC wave to produce half-wave varying DC.  

BRIDGE RECTIFIER

     A bridge rectifier can be made using four individual diodes, but it is also available in special packages containing the four diodes required. It is called a full-wave rectifier because it uses all the AC wave (both positive and negative sections). 1.4V is used up in the bridge rectifier because each diode uses 0.7V when conducting and there are always two diodes conducting, as shown in the diagram below. Bridge rectifiers are rated by the maximum current they can pass and the maximum reverse voltage they can withstand (this must be at least three times the supply RMS voltage so the rectifier can withstand the peak voltages).

SINGLE DIODE RECTIFIER

     A single diode can be used as a rectifier but this produces half-wave varying DC which has gaps when the AC is negative. It is hard to smooth this sufficiently well to supply electronic circuits unless they require a very small current so the smoothing capacitor does not significantly discharge during the gaps.

CONCLUSION

Bridge Rectifier Symbol

In this project,bridge rectifier used four diode (IN 4007):

Add fuse for provide overcurrent protection, of either the load or source circuit.

TRANSFORMER..

CONTENT

Various Type of Transformer

 -   A transformer is a piece of equipment that transform electrical power from one circuit to another circuit without changing the supply frequency and without any electrical connection.


-   Transformers convert AC electricity from one voltage to another with little loss of power. Transformers work only with AC and this is one of the reasons why mains electricity is AC.


-   Step-up transformers increase voltage, step-down transformers reduce voltage. Most power supplies use a step-down transformer to reduce the dangerously high mains voltage (240V in Malaysia) to a safer low voltage.


-   The input coil is called the primary and the output coil is called the secondary. There is no electrical connection between the two coils, instead they are linked by an alternating magnetic field created in the soft-iron core of the transformer. The two lines in the middle of the circuit symbol represent the core.


-   Transformers waste very little power so the power out is (almost) equal to the power in. Note that as voltage is stepped down current is stepped up.

-     The ratio of the number of turns on each coil, called the turns ratio, determines the ratio of the voltages. A step-down transformer has a large number of turns on its primary (input) coil which is connected to the high voltage mains supply, and a small number of turns on its secondary (output) coil to give a low output voltage. 

turns ratio =	Vp	=	Np	and	power out = power in
	Vs		Ns		Vs × Is = Vp × Ip

Vp = primary (input) voltage Np = number of turns on primary coil Ip  = primary (input) current

Vs = secondary (output) voltage Ns = number of turns on secondary coil Is  = secondary (output) current

    

     

  turns ratio = 

Vp

 = 

Np

   and   

power out = power in   

Vs

Ns

Vs × Is = Vp × Ip

Vp = primary (input) voltage
Np = number of turns on primary coil
Ip  = primary (input) current

   

Vs = secondary (output) voltage
Ns = number of turns on secondary coil
Is  = secondary (output) current

CONCLUSION

Transformer of Circuit Symbol

In this project, the transformer is a main component which as supply voltage on my project: