Week 7(Installation Of Equipment and Testing)

Assalamualaikum..

Last week I told about my circuit discription..
Now it's time to story about how the installation of the equipment and testing circuit.
During designing the whole circuit,
it is important to us to take into account the heat released by the electronic components.
Therefore,
the heat sink has been used in this project
to mitigate the effects of heat on the components of the voltage regulator
that in which the component is a component of many release heat.
Furthermore,
low power fan was used to remove the heat trapped in the casing is a variable power supply.
When all are ready, it is time to test.
This is to ensure that able to operate well without any defects.
During the process of implementing the proposed project,
planning and careful management is vital to ensure the project run smoothly.
There are various methods that can be used
to carry out the project and to obtain information.






The most basic things we measure are voltage and current.
A multimeter is also great for some basic sanity checks and troubleshooting.

Week 7(Discription Of The Project)

Circuit 1. Trigger circuit diagram of the versatile optical trigger

MEL 12 phototransistor, TR1 is a very sensitive device
incorporating an amplifying circuit in the form of a Darlington pair.
In this circuit, we do not make connection to the base in the trigger circuit
because the light energy falling on the phototransistor generate the equivalent of a small base current.
This is amplifier within the device to produce a collector-emitter current
in the region of 3mA in bright light.
When the light is shining on the phototransistor,
the current flow’s result through resistor R1 and level control VR1 is series.
If the light level increase, the current through phototransistor TR1 increase.
The voltage across R1 and VR1 increase and the voltage at pin 2 falls.
The fall in voltage at the inverting input (-) of an op-amp produce a rise in voltage at the output.
The op-amp is connected as a comparator,
with no negative feedback,
so it full open loop gain of around 200,000 comes into play.

Circuit 2. Circuit diagram for the differentiator circuit

The differentiator circuit diagram is a based on a second op-amp, IC2.
It takes its input from the trigger circuit.
Input A is from the junction of the voltage divider resistor R2/R3,
which sits at half the supply voltage.
Input B comes from the output junction of the trigger op.amp, IC1
and coupled to the inverter input (pin 2) of IC2 through C2.
The output of this op-amp is then used to drive TR2
and switch the load and l.e.d on or off.

From this circuit,

An increase in input voltage produce a fall in output voltage

Then, output is proportional to R and C. 

so, we can adjust the sensitivity by adjusting VR2

An Output is proportional to the rate of change of input voltage. 

This mean that even a very short and small input pulse 

can produce a high output pulse provide that the rate of change is high.

The third point above makes the circuit a little too sensitive to small “spikes” 

on the signal from IC1. 

Therefore, 

capacitor C1 is connected across the input to eliminate the effect of such spikes. 

When the light level on the sensor rises quickly, the output of IC2 falls. 

A low pulse passes across capacitor C3 to the input of the flip-flop IC3b/IC3c.
This type of flip-flop, built from two NAND gates, is stable if both its input are high.
Resistor R8 and R9 provide for this.

However,
a negative pulse arriving by way of C3 will briefly make pin 6 low
and so set the flip-flop, its output at pin 4 goes high.
The rising output is used to switch the transistor TR2 in the trigger circuit(fig 1).
The load is energized and D1 comes on.
The flip-flop is energized and D1 comes on.
The flip-flop is reset by briefly pressing push switch S1. 

Week 6(How The Circuit Function And Connect)

Assalamualaikum..
For this week, I have to tell about the circuit function and connection.

The first important component in this block diagram is phototransistor.
The phototransistor is very sensitive device incorporating an amplifying circuit in the form.
 After that, buffer and differentiator (op-amp),
there is an optional extra stage to this project
and it’s also unaffected if light level change slowly
but show a sharp change in output when the level change rapidly. 

And the last part is switch and the load.
The function for the switch for tuning on and off the circuit.
When there is no voltage on the gate,
the channel exhibits its maximum conductance
and when there is no voltage on the gate, there is in effect no channel.
When the light is shining on the phototransistor,
the current flow’s result through resistor R1 and level control VR1 is series.
If the light level increase, the current through phototransistor TR1 increase.

The voltage across R1 and VR1 increase and the voltage at pin 2 falls.
The fall in voltage at the inverting input (-) of an op-amp produce a rise in voltage at the output.
The op-amp is connected as a comparator, with no negative feedback,
so it full open loop gain of around 200,000 comes into play.
The differentiator circuit diagram is a based on a second op-amp, IC2.
It takes its input from the trigger circuit. 
Input A is from the junction of the voltage divider resistor R2/R3,
which sits at half the supply voltage.
Input B comes from the output junction of the trigger op.amp,
IC1 and coupled to the inverter input (pin 2) of IC2 through C2.
The output of this op-amp is then used to drive TR2
and switch the load and l.e.d on or off.

Week 5(The Components)

Assalamualaikum..
today I want to continue update about the component that I've updated yesterday..

Light Emitting Diode(LED)


A light-emitting diode (LED) is a semiconductor light source.
LEDs are used as indicator lamps in many devices and are increasingly used for general lighting.
Appearing as practical electronic components in 1962,
early LEDs emitted low-intensity red light,
but modern versions are available across the visible, ultraviolet,
and infrared wavelengths, with very high brightness.

When a light-emitting diode is switched on,
electrons are able to recombine with holes within the device,
releasing energy in the form of photons.
This effect is called electroluminescence,
and the color of the light (corresponding to the energy of the photon)
is determined by the energy band gap of the semiconductor.

An LED is often small in area (less than 1 mm2),
and integrated optical components may be used to shape its radiation pattern.
LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching.
However, LEDs powerful enough for room lighting are relatively expensive,
and require more precise current and heat management than compact fluorescent lamp sources of comparable output.
Light-emitting diodes are used in applications as diverse as aviation lighting,
automotive lighting, advertising, general lighting, and traffic signals.
LEDs have allowed new text, video displays, and sensors to be developed, while their high switching rates are also useful in advanced communications technology.
Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players and other domestic appliances.
LEDs are also used in seven-segment display.


OPERATIONAL AMPLIFIER

Week 5( Doing Research About All The Components

Assalamualaikum..
Have a nice day..

This week, I have to study some of the components that I have bought last week.
After doing the researched about all the components,
this is all the information that I've got.

This is the circuit that is flexible enough to cater for many different applications.
Application for basic circuit includes switching on a porch lamp at dusk,
briefly sounding the buzzer when someone’s shadow falls on the sensor.
With the addition of second circuit board,
there is an optional extra stage to this project, called Differentiator.
This changes the response of the trigger with the differentiator incorporated into the circuit.

It is unaffected if light levels change slowly
but shows a sharp change in output when the level change rapidly.

MEL 12 PHOTOTRANSISTOR
This is very sensitive device incorporating an amplifying circuit in the form of a Darlington pair.
However we do not make connection to the base in this trigger circuit
because the light energy falling on the phototransistor generates the equivalent of a small base current.
This is amplified within the device
to produce a collector emitter current in the region of 3mA in bright light.
Although ordinary transistors exhibit the photosensitive effects if they are exposed to light,
the structure of the phototransistor is specifically optimized for photo applications.
The phototransistor has much larger base and collector areas than would be used for a normal transistor. These devices were generally made using diffusion or ion implantation.
Early phototransistors used germanium or silicon throughout the device giving a homo-junction structure.
The more modern phototransistors use type III-V materials such as gallium arsenide.
Hetero structures that use different materials either side of the p-n junction are also popular
because they provide a high conversion efficiency.
These are generally fabricated using epitaxial growth of materials that have matching lattice structures.
These photo transistors generally use a mesa structure.
Sometimes a Schottky (metal semiconductor) junction can be used
for the collector within a phototransistor,
although this practice is less common these days
because other structures offer better levels of performance.







RESISTOR
A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element.
The current through a resistor is in direct proportion to the voltage across the resistor's terminals.
This relationship is represented by Ohm's law.
The electrical functionality of a resistor is specified by its resistance:
common commercial resistors are manufactured
over a range of more than nine orders of magnitude.
When specifying that resistance in an electronic design,
the required precision of the resistance may require attention
to the manufacturing tolerance of the chosen resistor, according to its specific application.
The temperature coefficient of the resistance may also be of concern in some precision applications.




POTENTIOMETER
Potentiometers comprise a resistive element,
a sliding contact (wiper) that moves along the element,
making good electrical contact with one part of it,
electrical terminals at each end of the element,
a mechanism that moves the wiper from one end to the other,
and a housing containing the element and wiper.
Many inexpensive potentiometers are constructed
with a resistive element formed into an arc of a circle
usually a little less than a full turn, and a wiper rotating around the arc and contacting it.
The resistive element, with a terminal at each end, is flat or angled.
The wiper is connected to a third terminal, usually between the other two.
On panel potentiometers, the wiper is usually the center terminal of three.

For single-turn potentiometers,
this wiper typically travels just under one revolution around the contact.
The only point of ingress for contamination is the narrow space
between the shaft and the housing it rotates in.
Another type is the linear slider potentiometer,
which has a wiper which slides along a linear element instead of rotating.
Contamination can potentially enter anywhere along the slot the slider moves in,
making effective sealing more difficult and compromising long-term reliability.
An advantage of the slider potentiometer is that the slider position gives a visual indication of its setting.
While the setting of a rotary potentiometer can be seen by the position of a marking on the knob,
an array of sliders can give a visual impression of.








VN10KM n-channel Mosfet
A mosfet is used for intensifying or swapping electronic signals since it a semiconductor gadget.
It has three terminals, the collector, the emitter, and the base.
In which current in the base terminal
is used to control the flow of current between the emitter and the collector.
It is by far the most common transistor in both digital and analog circuits.
Enhancement-mode MOSFET operates using a positive input voltage
and has an extremely high input resistance (almost infinite)
making it possible to interface with nearly any logic gate or driver capable
of producing a positive output.
Also, due to this very high input (Gate) resistance
we can parallel together many different MOSFETs
until we achieve the current handling limit required.
While connecting together various MOSFETs may enable us to switch high currents or high voltage loads, doing so becomes expensive and impractical in both components and circuit board space.
To overcome this problem Power Field Effect Transistors or Power FET's were developed.
MOSFETs are voltage-controlled power devices.
If no positive voltage is applied between gate and source
the MOSFET is always non-conducting.
If we apply a positive voltage UGS to the gate
we'll set up an electrostatic field between it and the rest of the transistor.
The positive gate voltage will push away the 'holes' inside the p-type substrate and attracts the moveable electrons in the n-type regions under the source and drain electrodes.
This produces a layer just under the gate's insulator through which electrons can get into and move along from source to drain.
The positive gate voltage therefore 'creates' a channel
in the top layer of material between oxide and p-Si.
Increasing the value of the positive gate voltage pushes
the p-type holes further away and enlarges the thickness of the created channel.
As a result we find that the size of the channel
we've made increases with the size of the gate voltage and enhances
or increases the amount of current which can go from source to drain-
this is why this kind of transistor is called an enhancement mode device.



So, from the research,
I've been able to explaining and knowing detailed about components that will be used in project.
Tomorrow, I'll continue with another components overview and informations.
With this informations, I can gain my knowledge in exploring all the electronics components advantages me in present and future.

Wassalam.

Week 4 ( Buy Components at Jalan Pasar )

Assalamualaikum..
This week I have bought the components at Jalan Pasar.
Feel grateful because I found all the components that I need for my project.
The pictures below are the components that I have found at an Electronics Shop there and the receipt as the prove buying components.



this is the shop where I go to buy all the components..


The components



This is all the component for the basic trigger circuit..
It's included Resistors, Potentiometer, semiconductors,
and miscellaneous..



And this is all the component for differentiator circuit..
that include Resistors, Potentiometer, Capacitors, Semiconductors, and miscellaneous..

Before I bought this components,
I take a time to discuss with the shopman about my project and ask him what I don't know about the component that I will use like the function of the components,
how to construct, troubleshoot and others until I feel satisfied with his explanation.




This is the prove that I buy the components at Jalan Pasar.
The total up for the receipt is RM 26.05.
With this receipt, I can claim the money with UniKL BMI which is give the allocation for their students in doing Final Year Project.

Today, I will study all the components and try to do research in the internet to collect all the information about the specifications and descriptions of the components.
I must prepared now, because later when I'm doing the demo at the presentation day, I can answer all the questions prepared by assessors about the circuit and how it connects with the components which is make the project works also functions properly. So, we stop until here today because I want to do many research and study the circuit.