The Engineering Projects

Introduction to BC640

Hello Everyone! Hope you’re well today. Thank you for viewing this read. In this post today, I’ll be discussing the Introduction to BC640. BC640 is a bipolar junction transistor that belongs to the PNP transistor family. It is composed of silicon material and comes in a TO-92 package. It is used to drive load under 500mA. In this post, you’ll get to know everything related to BC640 covering pinout, working, alternatives, applications, and physical dimensions. Keep reading.

Introduction to BC640

• BC640 is a PNP bipolar junction transistor mainly used for amplification and switching purpose.
• It comes with three pins called the emitter, base, and collector.
• The base is the main terminal responsible for the entire transistor reaction. The small current change at the base terminal is used to control large current across remaining terminals. The reason, it’s also called current controlled device in contrast to FET (field-effect transistors) which is a voltage-controlled device.
• BC640 carries three layers where one n-doped layer is placed between two p-doped layers.
• As this is a PNP transistor, here current flows from emitter to collector as opposed to NPN transistor where current flows from collector to emitter.

• Both holes and electrons play a critical role in conductivity. In the case of PNP transistors, holes are the majority carriers and electrons are major charge carriers in NPN transistors.
• It is important to note that NPN transistors are preferred over PNP transistors because the movement of electron is better and faster than the movement of holes. In some electronic projects, both PNP and its complementary NPN are combined and incorporated into a single circuit.

• When two diodes are joined together from the cathode side, they produce PNP transistors. Here N-layer represents the base terminal while remaining layers represents emitter and collector respectively.

• In PNP transistor there is no current at the base side when the transistor is turned ON, while in NPN transistor electrons start flowing through the base terminal when the bias voltage is applied.

 

Where To Buy?
No.	Components	Distributor	Link To Buy
1	BC640	Amazon	Buy Now

BC640 Datasheet

• It’s always better to sift through the datasheet and get a hold of the main features of the component.
• Download BC640 datasheet by clicking the button given below:

Download BC640 Datasheet

BC640 Pinout

BC640 carries three pins named: 1: Emitter 2: Base 3: Collector The following figure shows the pinout of BC640.

• All these pins are used for the external connection with the electronic circuits, and they all are different in terms of their functions and doping concentrations.
• The doping concentration in the emitter terminal is higher than both base and collector terminals.

BC640 Working Principle

• Both PNP and NPN transistors almost work similarly with some exceptions.
• The voltage polarities and current directions in PNP transistors appear opposite compared to NPN transistors.
• The base is still considered the main area responsible for the overall transistor action.

• As holes are majority carriers in this PNP transistor, now holes are emitted from the emitter terminal (electrons are emitted from the emitter in case of NPN transistor) which are then collected by the collector.
• It is important to note that when there is no current present at the base terminal, PNP transistor is turned ON and when current flows through the base it is considered turned OFF.

BC640 Power Ratings

The following image shows the absolute maximum ratings of BC640.

Absolute Maximum Ratings BC639
No.	Rating	Symbol	Value	Unit
1	Collector-Emitter Voltage	Vce	80	V
2	Collector-Base Voltage	Vcb	80	V
3	Emitter-Base Voltage	Veb	5	V
4	Collector Current	Ic	500	mA
5	Total Device Dissipation	Pd	625	mW
6	Transition Frequency	ft	50	MHz
7	Storage Temperature	Tstg	-55 to 150	C

• Both collector-emitter and collector-base voltages are 80V while the emitter-base voltage is only 5V which means the only 5V is required to trigger the transistor reaction.
• Device dissipation is 625mW which implies the amount of heat it produces as a byproduct due to its primary action.
• Collector current is 500mA which projects the value of load it can drive. The transition frequency is 50MHz which is a measure of the high-frequency operating characteristics of a transistor.
• These are the stress ratings. Make sure these ratings don’t surpass the absolute maximum ratings, else they will damage the component, thus the entire project.
• Moreover, extended exposure to stresses above recommended absolute maximum ratings can influence the device reliability.

Difference between PNP and NPN transistors

• Current direction is the major difference in both NPN and PNP transistors.
• Recall, current flows from emitter to collector in PNP transistor when a negative voltage is applied to the base terminal and current flows from collector to emitter in NPN transistor when a positive voltage is applied at the base terminal.
• In both cases, the base terminal is responsible for the electron reaction.
• In NPN transistor, the transistor turns on when current flows through the base terminal, and in case of PNP transistor, the device turns on when there is no current at the base terminal.

• Both transistors are the primary components used in modern electronic projects.
• It is important to note that both NPN and PNP transistors are interchangeable and are made up of two back to back diodes where one is forward biased and the other is reverse biased.
• The main difference stands in the polarities of the applied voltage at the base terminal and current direction as mentioned above.

• In conclusion, both PNP and NPN are interchangeable and work perfectly well if we change the polarity of the applied voltage.

BC640 Alternatives

Following are BC640 alternatives:

• BC618
• BC635
• BC636
• BC637

Better check the pinout of the alternatives before embedding them into your projects, as it’s likely they might carry different pinout than BC640. The complementary NPN transistor to the BC640 is BC639.

BC640 Applications

The following are some applications of the BC640.

• It is used to source current, i.e. current flows out of the collector.
• Used for switching and amplification purpose.
• Used in electronic motors to control current.
• Employed in the push button.
• Used in robotics and instrumentation.
• Finds applications in Darlington pair circuits.

BC640 Physical dimensions

The following figure shows the physical dimensions of the BC640. That’s all for today. I hope you’ve got an insight into the Introduction to BC640. If you have any question, you can approach me in the comment section below, I’d love to help you the best way I can. You’re most welcome to share your feedback and suggestions, they help us provide quality work. Thank you for reading this post.

Soil Moisture Sensor Library For Proteus

Update: We have created a new version of this library, which you can check here: Soil Moisture Sensor Library for Proteus V2.0.

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Hi Friends! Hope you’re well today. I welcome you on board. In this tutorial, I’ll be discussing the Soil Moisture Sensor Library for Proteus. You won't find Soil Moisture Sensor Library in Proteus and we’re going to share its Proteus Library very first time. I have previously shared many Proteus Libraries for digital and analog sensors and today I’m discussing something new. Excited to get a hold of the Soil Moisture Sensor Library? Me too. In the upcoming days, I’ll keep sharing different libraries related to sensors. If you’re curious to sneak into the nitty-gritty of sensors not available in the Proteus library already, pop your suggestion in the comment section below. I’ll try my best to comply with your suggestions and walk you through something brand new.

Soil moisture sensors are used to measure the water content in the soil. They use capacitance to measure the dielectric permittivity of the soil which defines the function of the water content. Before further ado, let’s dive in and have a look at How to download and simulate Soil Moisture Sensor Library for Proteus:

Where To Buy?
No.	Components	Distributor	Link To Buy
1	LCD 20x4	Amazon	Buy Now
2	Arduino Uno	Amazon	Buy Now

Soil Moisture Sensor Library For Proteus

• You can download the Proteus Library zip file of Soil Moisture Sensor Library by clicking the button below.

Download Proteus Library Files

• It’s a .zip file that contains two folders inside i.e. Proteus Library & Proteus Simulations.
• The real fun starts right here right away.
• Open proteus library folder that contains three files named:
  • SoilMoistureSensorTEP.IDX
  • SoilMoistureSensorTEP.LIB
  • SoilMoistureSensorTEP.HEX
• Copy and paste these three files in the Library folder of your Proteus software:

• Now, we need to run the Proteus ISIS software and don't forget to restart, if it's already open.
• Look for the Soil Moisture in the component’s search box as shown below.

• After installing the Library successfully, you’ll get similar results as below:

• You can see in the figure above we have one Soil Moisture Sensor.
• Now simply place this Soil Moisture Sensor in your Proteus workspace, as mentioned below:

• You can see in the figure above, I have placed one Soil Moisture Sensor inside the Proteus workspace.
• This sensor carries 4 pins in total, named:

• V (Vcc): We’ll provide +5V here.
• G (GND): We’ll provide ground here.
• Ao (Out): It’s an analog output signal from the sensor.
• TestPin: It is used for simulation purposes only. Soil Moisture Sensor doesn’t contain this pin in real.

Adding Sensor’s Hex File

• After this drill, we’ll add the Sensor’s Hex File, which we have downloaded and placed in the Library folder.
• To do that, right-click on your Soil Moisture Sensor and then click on “Edit Properties” as below:

• Or you can double click the Soil Moisture Sensor, it will pop the window below:

• Click on the Browse button and add SoilMoistureSensorTEP.HEX file available in the Proteus Library section as shown in the figure below:

• After adding the Sensor’s Hex File, click on the ‘OK’ button to close the ‘Edit Properties’ Panel.
• Our Soil Moisture Sensor is now ready to simulate in our Proteus ISIS.
• We’ll design a small circuit to thoroughly understand the working of this Soil Moisture Sensor.

Proteus Simulation of Soil Moisture Sensor

• Here, I’m designing a simple circuit. I’ve attached a variable resistor with the Test Pin & added a Voltmeter at the Output pin, as shown in the figure below:

• This resister defines the soil water content in the proteus simulation.
• When the resistance is maximum at the test pin, the circuit shows zero volts across the voltmeter, which means the sensor is either in the dry ground or taken out of the ground i.e. giving zero moisture value of the water content.
• And when resistance is zero, the circuit will show the maximum voltage across the voltmeter which indicates the sensor is inserted in a wet ground i.e. water contents in the soil are too high.
• This is important. We have attached the output pin with an LC filter. This filter is not required in real hardware implementation.
• We are using it in Proteus Simulation only as Proteus gives the peak-to-peak value and we have to convert that PP value into Vrms.
• If you are working on a real sensor then you don’t need to add this LC circuit.
• Now, let’s run this Proteus Simulation and if you have done everything as mentioned, it will show the result mentioned in the figure above.

Simulation of Soil Moisture Sensor with Arduino

Now, let's interface this sensor with a microcontroller.

• We have attached the output of the sensor appearing across the voltmeter with the A0 pin of the microcontroller as below.

You can see we get the analog value 1019 when the voltage across the voltmeter is 4.98V

This is it. I hope you find this tutorial helpful. This will help engineering students in simulating their semester projects in proteus. In the next tutorials, I’ll be sharing and adding more libraries of sensors. You’re most welcome to share your suggestions with the sensors you want me to libraries of. If you’re unsure or have any questions, you can ask me in the section below. I’ll help the best way I can. Thank you for reading this article.

Introduction to BC327

Hi Friends! Glad to see you here. I welcome you on board. In this post today, I’ll be discussing the Introduction to BC327. BC327 is a bipolar junction transistor that falls under the family of PNP transistors. It is composed of silicone material and is used to drive load under 800mA. It’s a current-controlled device that carries three pins where small current generated at the one terminal is used to control large current at the other terminals. Read this post all the way through as you’ll get to know all nuts and bolts of BC327 covering pinout, working, power ratings, applications, and physical dimensions. Let’s get started.

Where To Buy?
No.	Components	Distributor	Link To Buy
1	BC327	Amazon	Buy Now

Introduction to BC327

• BC327 is a PNP bipolar junction transistor that comes in the TO-92 package and is used for switching and amplification purpose.
• It comes with three pins named emitter, base, and collector that are mainly used for external connection with the electronic circuit.
• BC327 is incorporated with three layers where one n-doped layer is sandwiched between two p-doped layers. The n-doped layer is negative while the p-doped layer is positively charged.

• This transistor incorporates 800mA collector current, hence it is easily employed to drive a variety of heavy loads.

• Collector dissipation is 625mW while the maximum current gain is 630 which makes it a suitable pick for audio amplification purposes.
• Transistors are mainly divided into two types named NPN and PNP transistors this BC327 transistor belongs to the PNP transistor family.
• Both transistors are different in terms of their charge carriers used for conductivity.
• Electrons are major carriers in NPN transistors while holes are major carriers in PNP transistors.
• When two diodes are combined from the cathode side, they constitute a PNP transistor where the N-doped layer represents the base side while the other two p-doped layers represent the emitter and collector respectively.

• You know it already, the movement of electrons is far better and faster than the movement of holes. The reason NPN transistors have a leg over PNP transistors for their quick response in conductivity.

BC327 Datasheet

• To understand the component thoroughly, it’s always wise to sift through the datasheet.
• Download BC327 Datasheet by clicking the button below:

BC327 Pinout

BC327 comes with three pins named 1: Emitter 2: Base 3: Collector The following figure shows the pinout of BC327.

• These pins are used for external connection with the electronic circuit. The small current change at the base terminal produces a large current change across other terminals.
• The base terminal plays a key role in differentiating both NPN and PNP transistors.
• In NPN transistor current flows through the base side when voltage is applied while in PNP transistor no current flows through the base terminal when the transistor is turned ON.

BC327 Working Principle

• When current flows through the base terminal in this PNP transistor, the transistor is turned OFF, and on the other hand, when there is no current at the base side, the transistor is turned ON.
• PNP works the same as NPN transistor but in the opposite fashion. The base still controls the large current across other terminal but here current flows in the opposite direction i.e. from emitter to collector.
• And instead of electrons emitted in the case of NPN transistor, holes are emitted by the emitter in PNP transistor that are then collected by the collector.

BC327 Power Ratings

The following table shows the absolute maximum ratings of BC327.

Absolute Maximum Ratings BC639
No.	Rating	Symbol	Value	Unit
1	Collector-Emitter Voltage	Vce	45	V
2	Collector-Base Voltage	Vcb	50	V
3	Emitter-Base Voltage	Veb	5	V
4	Collector Current	Ic	800	mA
5	Collector Power Dissipation	Pc	625	mW
6	Junction Temperature	Tj	150	ºC
7	Storage Temperature	Tstg	-55 to 150	ºC

• These are stress ratings that can make or break your entire project. Make sure ratings don’t exceed these absolute maximum ratings else you may compromise your component.
• Similarly, if these ratings are applied for more than the required time, they can affect the reliability of the device.

Difference between PNP and NPN Transistors

• The BC327 transistor carriers the same characteristics as NPN transistors with a few exceptions.
• In the case of PNP transistors, all current directions and voltage polarities will be reversed compared to NPN transistors.
• The NPN transistor sources current through the base terminal while PNP sinks current into the base terminal, the reason it’s also called a sinking device.
• In PNP transistor the base terminal is more negative than the emitter terminal. And all these terminals are different in terms of their doping concentration.
• The emitter terminal is highly doped and comes with 100% current of the transistor while the base terminal is lightly doped and is responsible for the transistor action and controls the number of holes emitter from the emitter which are then collected by the collector.

• The collector terminal is bigger compared to other terminal and is lightly doped.
• Both NPN and PNP also differ with respect to the applied source voltage i.e. in case of NPN transistor source voltage is applied at the collector side while in case of PNP transistor source voltage is applied at the emitter side.
• A load resistor is also used while working with this BC327 PNP transistor that controls the current in the collector terminal.
• Plus, biased voltage is applied at the base terminal that initiates the transistor action and it is coupled with the base resistor to resist and limit the current flowing through this terminal.

BC327 Alternatives

The following are alternatives to BC327.

• 2N4403
• BC488
• BC638
• 2N4402
• 2N3702
• 2N3703
• BC486
• BC490
• BC328

The pinout settings of the alternative may differ from the actual BC327. It’s wise to check the pinout of the transistor before employing it in your electronic circuit. NPN Complementary of BC327 is BC337. Since they both form a complementary pair, they can be employed together in many electronic projects.

BC327 Applications

BC327 comes with the following applications:

• Used for signal amplification and switching purposes.
• Finds application microcontrollers to drive heavy loads.
• Used in audio amplifiers and multiple preamplification stages.
• Employed to drive loads under 800mA.
• Used in push-pull configuration circuits.
• Used in medium-speed switching and high-frequency amplifiers.

BC327 Physical dimensions

The following figure shows the physical dimensions of the BC327. That’s all for today. I hope you find this read useful. If you have any questions, you can approach me in the section below. I’d love to help you the best way I can. Keep us updated with your valuable feedback and suggestions, they help us create quality content. Thank you for reading this post.

Introduction to BC550

Hi Guys! Happy to see you here. Thank you for viewing this read. In this post today, I’ll walk you through the complete Introduction to BC550. BC550 is a low-power low-frequency general-purpose bipolar transistor. It is mainly used to drive loads under 100mA. BC550 carries three terminals where a small current across one terminal is used to control the large current across the remaining terminals. It’s primarily used for amplification and switching purposes. Transistors are critical components and building blocks of modern electronic circuits. Bipolar junction transistors are divided into two main types named NPN transistors and PNP transistors. The BC550 falls under the category of NPN transistors and is available in a plastic TO-92 case. I suggest you read this entire post all the way through as you’ll get to know all nitty-gritty of BC550 i.e. datasheet, pinout, working principle, power ratings, applications, and physical dimensions.

Keep reading.

Where To Buy?
No.	Components	Distributor	Link To Buy
1	BC550	Amazon	Buy Now

Introduction to BC550

• BC550 is an NPN bipolar junction transistor mainly used for switching and amplification purpose.
• It incorporates three pins called the emitter, base, and collector. Where small current change at the base terminal is used to induce large current change across other terminals.
• BC550 carries three layers i.e. two N-doped layers and one P-doped layer. The P-doped layer indicates a positively charged layer that stands between the two N-doped layers that are negatively charged.
• When this transistor acts as a switch it is used to turn ON and OFF the input signal. When a powerful signal passes through the transistor, it turns ON the switch while lack of signal turns the switch OFF.
• When several thousands of millions of transistors are formed together, they can be incorporated into integrated circuits or in discrete components.
• BC550 is composed of semiconductor material. Silicon is mostly used to form these NPN transistors.
• In this NPN transistor, electrons are the majority carriers used for conductivity as opposed to PNP transistors where conductivity is carried out with holes as majority carriers.
• It is important to note that the movement of electrons is far better and faster than the movement of holes, the reason NPN transistors are better, thus preferred over PNP transistors.
• The main difference between NPN and PNP transistors is the behavior of the base terminal. In NPN transistors, current flows through the base terminal while in the case of PNP transistors no current flows through the base terminal when a transistor is ON.
• Also, the current flows from collector to emitter in NPN transistors, and in PNP transistors current flows from emitter to collector.
• Computer circuit boards are the common example of NPN transistors that carry millions of transistors used to store memory in the form of binary code.

BC550 Datasheet

• To understand the component thoroughly, it’s always wise to scan the datasheet.
• You can download BC550 Datasheet by clicking the button below:

BC550 Pinout

BC550 comes with three pins called

1. Emitter
2. Base
3. Collector

The following figure shows the pinout of the BC550:

• All these terminals are different in terms of their doping and functions.
• The emitter terminal is highly doped compared to the other two terminals.
• The emitter emits the electron into the base terminal which controls the number of electrons. The collector terminal is used to collect the number of electrons.

BC550 Pin Configuration

BC550 can be embedded in the following three configurations:

1. Common emitter configuration
2. Common collector configuration
3. Common base configuration

• Mostly amplification is carried out using a common emitter configuration as it comes with the exact voltage and current ratings required for amplification purposes.
• The amplification factor is an important factor used to define the nature of amplification. It’s a ratio between collector current and base current and is denoted by ß.
• The current gain is another factor which is a ratio between collector current and emitter current. It is denoted by a and is known as alpha. The alpha value ranges from 0.95 to 0.99 but mostly its value is taken as unity.

BC550 Working Principle

• In BC550, the base works as an electron valve that controls the number of electrons. When a voltage is applied across the base terminal, it triggers the electron reaction. Thus, the emitter starts emitting the electrons into the base terminal which are then collected by the collector.
• A small change in input voltage at the base terminal produces a large change in output voltage across other terminals. This phenomenon is used for amplification purposes.

• The collector voltage is always positive with respect to the emitter terminal while the base terminal is positive with respect to the emitter.
• And the collector terminal is combined with the load voltage using a resistor which is used to control the flow of current.

BC550 Power Ratings

The following table shows the absolute maximum ratings of BC550:

Absolute Maximum Ratings BC639
No.	Rating	Symbol	Value	Unit
1	Collector-Emitter Voltage	Vce	45	V
2	Collector-Base Voltage	Vcb	50	V
3	Emitter-Base Voltage	Veb	5	V
4	Collector Current	Ic	100	mA
5	Collector Power Dissipation	Pc	500	mW
6	Junction Temperature	Tj	150	ºC
7	Storage Temperature	Tstg	-55 to 150	ºC

• Emitter-Base voltage is 5V, which means the only 5V is required to trigger the base terminal, thus the entire transistor. While Collector-Base and Collector-Emitter voltages are 50V and 45V respectively.
• The collector current is 100mA i.e. it can drive loads with a value under 100mA.
• It’s wise to do your due diligence before incorporating this tiny device into your project as values exceeding absolute maximum ratings can severely damage the component.
• Plus, make sure you don’t apply these values for more than the required time, else they can affect the device's reliability.

BC550 Alternatives

BC550 equivalent are:

• BC546
• BC547
• BC548
• BC549

The complementary PNP transistor of the BC550 is BC560. BC550 Applications

• Used for amplification and switching purposes.
• Can be employed in the current mirror and H-bridge circuits.
• Used in linear amplifier and impedance buffering.
• Finds applications in oscillator and comparator circuits.
• Used in Astable and Bistable multivibrator circuits.
• Used for pre-amplification stages in electronic circuits.

BC550 Physical dimensions

The following figure shows the physical dimensions of the BC550: That’s all for today. Hope you’ve got a clear insight into the Introduction to BC550. You’re most welcome to ask your queries in the section below. I’d love to help you the best way I can. Feel free to keep us updated with your valuable suggestions and feedback. Thank you for reading this post.

Introduction to BC639

Hi Friends! Happy to see you here. I welcome you on board. In this post, I’ll walk you through the Introduction to BC639. BC639 is a high current gain bipolar junction transistor that falls under the NPN transistor family. It constitutes a high collector current and low collector-emitter saturation voltage and is widely used for amplification and switching purposes. It is used to drive load under 500mA. Collector Dissipation is 0.625W while DC Current Gain (hfe) ranges from - 40 to 160 with transition frequency 200MHz. In this post, I’m going to discuss all nitty-gritty of the BC639 transistor covering pinout, working, power ratings, alternatives, applications, and physical dimensions. Continue reading.

Introduction to BC639

• BC639 is an NPN bipolar junction transistor that carries high collector current and low collector-emitter saturation voltage.
• It is composed of silicon material and comes in a TO-92 package.
• BC639 carries three pins named emitter, base, and collector.

• It is mainly known as a current-controlled device where the base terminal is responsible for the entire transistor action.
• BC639 contains three layers where one p-doped layer sits between two n-doped layers.
• The small input current change at the base terminal is used to control large output current at the other two terminals.
• The base terminal controls the flow of electrons and acts as a control value. The emitter terminal emits the electron passing through the base terminal which are then collected by the collector terminal.
• Both electrons and holes play a critical role in conductivity carried out by these tiny components. In the case of NPN transistor electrons are the major charge carriers while in the case of PNP transistors holes are major carriers.
• The movement of electrons is faster and better than the movement of holes for conductivity. The reason these NPN transistors are preferred over PNP transistors for the making and execution of electronic projects.

Where To Buy?
No.	Components	Distributor	Link To Buy
1	BC639	Amazon	Buy Now

BC639 Datasheet

• It’s always wise to scan through the datasheet and get a hold of the main features of the component.
• Download BC639 datasheet by the link given below:

BC639 Pinout

BC639 comes with three pins called 1: Emitter 2: Base 3: Collector The following figure shows the pinout of BC639. Recall, BC639 is used to amplify the weak signal. As this is an NPN transistor, here current flows from collector to emitter as opposed to PNP transistor where current flows from emitter to collector. All these terminals are different in terms of their functions and doping concentrations. The emitter side is highly doped as opposed to the other two terminals. These pins are used for external connection with the electronic circuits.

BC639 Pin Configuration

BC639 transistor is employed in the following three main configurations:

• 1: Common emitter configuration
• 2: Common collector configuration
• 3: Common base configuration

• Common emitter configuration is used for the amplification purpose as it contains the suitable voltage and current ratings needed for amplification purposes.
• The nature of amplification is demonstrated by the amplification factor that is a ratio between collector current and base current. It is denoted by ß.
• The current gain is another important factor used to describe the nature transistor. It is a ratio between collector current and emitter current. It is called alpha and is denoted by a. The alpha value stands from 0.95 to 0.99 but frequently its value is taken as unity.

BC639 Working Principle

• It all starts from the base terminal. When the voltage is applied at the base pin, it ignites the electron reaction inside the transistor. This base pin controls the number of electrons emitted by the emitter terminal. The base pin acts as an electron valve and is responsible for conductivity inside the entire component.
• When BC639 acts as an amplifier, the small current at the base terminal (which acts as an input current) is used to control a much larger electric current at both emitter and collector terminals.
• And when it operates as a switch, it converts the small current at one part of the transistor into a much larger current across the remaining parts of the transistor.
• The base pin is positive with respect to the emitter terminal and collector voltage is always positive with respect to the emitter terminal.
• It’s important to note that the collector terminal is combined with the load voltage using resistor that limits and controls the flow of current.

BC639 Power Ratings

The following table shows the absolute maximum ratings of BC639.

Absolute Maximum Ratings BC639
No.	Rating	Symbol	Value	Unit
1	Collector-Emitter Voltage	Vce	60	V
2	Collector-Base Voltage	Vcb	60	V
3	Emitter-Base Voltage	Veb	5	V
4	Collector Current	Ic	500	mA
5	Current Gain	hfe	-40 to 160
6	Transition Frequency	ft	200	MHz
7	Storage Temperature	Tstg	-55 to 150	C

• Both collector-emitter and collector-base voltages are 60V while the emitter-base voltage is a mere 5V, which means the only 5V is required to trigger the electron reaction at the base terminal. And collector current is 500mA which projects that it can drive load under 500mA.
• The storage junction temperature range is -55 to 150C. While collector Dissipation is 0.625W and DC Current Gain (hfe) ranges from - 40 to 160 with transition frequency 200MHz.
• These are stress ratings that define the working of a component under certain values.
• If these values exceed the absolute maximum ratings, they can damage the component, thus the entire project.
• Do your due diligence before applying this component into your project and make sure you work under these mentioned ratings.
• Also, if these ratings are applied more than the required time, they can affect device reliability. Be careful.

BC639 Alternatives

KSC1009C transistor can be replaced by BC639. The complementary transistor of BC639 is BC640.

BC639 Applications

BC639 is used in the following applications:

• Used for amplification and switching purposes.
• Used in oscillator and comparator circuits.
• Employed in the current mirror and H-bridge circuits.
• Used for pre-amplification stages in electronic circuits.
• Finds applications in linear amplifier and impedance buffering.
• Incorporated in oscillator and comparator circuits.
• Used in Astable and Bistable multivibrator circuits.

BC639 Physical dimensions

The following figure shows the physical dimensions of the BC639. This is it. I hope you find this article helpful. I strive to share easy to read and easy to digest information. If you are unsure or have any question, you can pop a comment below, I’d love to help you the best way I can. Keep sharing your valuable feedback and suggestions, they help us create quality content. Thank you for your precious time.

Introduction to BC549

Hi Friends! I hope you’re well today. I welcome you on board. In this post, I’m going to discuss the Introduction to BC549. BC549 is a general purpose bipolar junction transistor that belongs to NPN transistor family. It contains three pins where small current change in one terminal produces a much large current change across other terminals. In other words, it is nothing but a current booster. It is known as a low power low voltage current controlled device and is used for switching and amplification purpose.  In this article I’ll be discussing complete details of BC549 transistor i.e. pinout, working principle, power ratings, physical dimensions and applications. Stay tuned.

Introduction to BC549

• BC549 is an NPN general-purpose bipolar junction transistor. It carries three pins named emitter, base, and collector and is available in TO-92 and SOT54 package.
• BC549 transistor contains three layers i.e. two N-doped layers and one P-doped layer. The P-doped layer stands between two N-doped layers. Plus, it contains two PN junctions where one is forward biased and the other is reverse biased.

• When no voltage is applied at the base terminal it is considered as grounded. In this case, the transistor acts like an open switch where both emitter and collector remain open.
• When voltage is applied at the base terminals it gets biased and draws current which is used to connect other terminals and current starts flowing from collector to emitter terminal.
• As this is an NPN transistor, here current flows from collector to emitter when voltage is applied, unlike PNP transistor where current flows from emitter to collector.
• Plus, both electrons and holes play a vital role in conductivity. In NPN transistor electrons are majority charge carriers and in PNP transistor holes are majority carriers.
• The movement of electrons, however, is faster than the movement of holes, the reason NPN transistors are better and faster than PNP transistors.

BC549 Pinout

BC549 comes with three pins named:

• 1: Emitter
• 2: Base
• 3: Collector

Following figure shows the pinout diagram of BC549.

• All three pins are used for external connections with other circuits. These pins are different in terms of operation and doping concentration.
• The collector voltage is larger than the base voltage and emitter terminal is highly doped compared to other terminals.

BC549 Pin Configuration

BC549 transistor can be employed in three main configurations as follows:

• Common emitter configuration
• Common base configuration
• Common collector configuration

Common emitter configuration is mostly used for amplification purposes as it contains the exact current and voltage ratings required for amplification.

• The amplification factor is called beta and is denoted by ß. It is mainly used to define the nature of amplification. It’s a ratio between collector current and base current. In BC549, the amplification factor ranges from 420 to 800.
• Another important factor is the current gain which is a ratio between collector current and emitter current. It is known as alpha and is denoted by a. The alpha value stands from 0.95 to 0.99 but more often than not its value is taken as unity.

BC549 Working Principle

• In BC549, emitter-base voltage is 5V which means when 5V is applied at the base terminal it gets biased and triggers the electron reaction.
• In the NPN transistor, the base terminal behaves like a control valve that controls the number of electrons.
• When voltage is applied at the base terminal, emitter starts emitting the electrons into the base terminal which controls the number of electrons. These emitted electrons passing through the base are collected by the collector terminal of the transistor.
• Moreover, the collector current is a mere 100mA i.e. you cannot drive heave loads using this transistor.
• As the only 5V is required to start the electron reaction at the base terminal, it can be easily employed across microcontrollers and microprocessors.
• When BC549 operates as an amplifier, small current as an input signal at the base terminal is used to induce a much bigger electric current at the other terminals.
• And when it works like a switch, it switches the small current at one part of the transistor into a much larger current across the other parts of the transistor.
• When transistor acts as a switch, it carriers two distinct states i.e. values are stored in the form of zero and one. Memory chip used in a computer is a common example of an electronic device that contains billions of transistors which can be turned on and off individually.

BC549 Power Ratings

Follow figure shows the absolute maximum rating of BC549:

• Emitter-Base voltage and Collector-Emitter voltages are 5V and 30V respectively.
• And Collector-Base voltage is 30V with collector current 100mA i.e. it cannot drive loads carrying ratings more than 100mA.
• The current gain ranges from 420 to 800 and transition frequency is 100MHz.
• These are stress ratings. Before you employ this transistor into your project and execute, make sure the ratings don’t exceed from absolute maximum ratings, else they will damage the product, and worse, your entire project, eventually.
• Also, if these ratings are applied for more than the required time, they can affect device reliability.

BC549 Alternatives

The following are the alternatives of a BC549 transistor.

• BC547
• BC548
• BC550

The PNP complementary of BC549 are:

• BC559
• BC560

BC549 Applications

BC549 can be used in the following applications:

• Used in liner audio amplifiers.
• Employed in Darlington pairs and sensor circuits.
• Used in oscillator and comparator circuits.
• Finds application in current mirror circuits.
• Used in Astable and Bistable multivibrators.
• Used for impedance buffering and switching applications.
• Finds application in low noise stages in audio frequency equipment.

BC549 Physical dimensions

Follow figure shows the physical dimensions of BC549: That’s all for today. Hope you find this article helpful. If you are unsure or have any question, you can approach me in the section below. I’d love to help you the best way I can. You’re most welcome to keep us updated with your valuable feedback and suggestions, they help us produce quality content. Thank you for reading this article.

Introduction to BC548

Hi Friends! Glad to see you here. I hope you’re well today. In this post, I’ll walk you through the Introduction to BC548.  BC548 is a general-purpose transistor that falls under the family of NPN transistors. It carries three pins that are mainly used for external connection with the circuit. The small current at one terminal is used to control the large current at other terminals. Moreover, it can drive loads under 500mA and is available in TO – 92 package. I suggest you read this post all the way through as you’ll get to know all nuts and bolts of BC548 transistor i.e. pinout, working principle, power ratings, applications, and physical dimensions. Let’s jump right in.

Introduction to BC548

• BC548 is an NPN general-purpose transistor, comes with three pins named emitter, base and collector.
• A small current at the base side is used to control large current at the collector and emitter terminals. The reason, it’s normally called a current controlled device.

• Decent current gain and power dissipation make it a suitable pick for amplification circuits and pre-amplification stages in other electronic applications. Moreover, it is also used as a switch to carry the load below 500mA.
• This BC548 transistor belongs to the NPN family where it contains three layers i.e. two N-doped layers and one P-doped layer. The P-doped layer is sandwiched between two N-doped layers.
• Also, it contains two PN junctions where one is reverse biased and the other is forward biased.
• The NPN transistor is like an electron valve where the base terminal controls the movement of electrons. It is widely used for amplification purposes in many electrical and electronics projects.
• Plus, electrons behave like majority carriers in NPN transistors whereas in PNP transistor holes behave like majority carriers. In conclusion, the mobility of electrons is better than the mobility of holes, thus NPN transistors are better and faster than PNP transistors.

1. BC548 Pinout

BC548 contains three pins named:

• 1: Emitter
• 2: Base
• 3: Collector

Following figure shows the BC548 pinout:

• All these terminals are different in terms of operation and doping concentration.
• The base terminal controls the current, emitter is used to emit the number of electrons when voltage is applied at the base terminal which is then collected by the collector.
• The small increase in input voltage applied at the base terminal produces a large change in output voltage across both collector and emitter terminals. This practice is used for amplification purposes.
• The emitter terminal is highly doped as compared to collector and base terminals. Plus, the collector voltage is larger than the base voltage.

2. BC548 Pin Configuration

BC548 transistor is used in three main configurations as follows:

• Common base configuration.
• Common emitter configuration.
• Common collector configuration.

Common emitter configuration carries exact voltage and current ratings mainly used for amplification.

• The amplification factor is used to define the nature of amplification. It is called beta and is denoted by ß. It is a ratio between collector current and base current. As it’s a ratio between the same factor i.e. current, it contains no unit. In this NPN transistor, the amplification factor ranges from 110 to 800.
• Similarly, the ratio between collector current and emitter current is called current gain and is mainly known as alpha, denoted by a. The alpha value lies between 0.95 to 0.99 but most of the time its value is taken as unity.

3. BC548 Working Principle

• When the base terminal is grounded, both emitter and collector terminals remain disconnected.
• When the voltage is applied at the base terminal, it gets biased, forming a bridge between collector and emitter.
• As this is an NPN transistor, the current will flow from collector to emitter, unlike PNP transistors where current flows from emitter to collector.
• Though both electrons and holes play a key role in conductivity, in the case of NPN transistors, electrons are major charge carriers.
• The base terminal controls the number of electrons passing from collector to emitter and appears positive with respect to the emitter terminal.
• The applied voltage at the base terminals draws a small current which is then used to police the large current at the collector and emitter terminals.

4. BC548 Power Ratings

The following figure shows the absolute maximum ratings of BC548:

• Collector-Base voltage is 30V. While Emitter-Base voltage and Collector-Emitter voltages are 5V and 30V respectively.
• The Collector current is 500mA with maximum power dissipation 625mW at temperature 25C.
• And the current gain ranges from 110 to 800.
• It’s important to note that these values are called stress ratings. Before you employ this transistor into the required circuit, make sure these ratings don’t cross the absolute maximum ratings, else you can risk your transistor and thus the entire project.
• Plus, if these ratings are applied for an extended period, they can influence the device reliability.
• Note: these values are measured at T = 25 C

5. BC548 Alternatives

The following are equivalent transistors of BC548:

• 2N2222
• 2N3904
• BC547
• BC549
• BC550

They all belong to the NPN family. The PNP complementary of BC548 is BC558. The type of transistor you use depends on the ratings of load you intend to drive i.e. in case of BC548 you can drive loads under 500mA.

6. BC548 Applications

NPN type transistors are used in circuits when you intend to sink the current. BC548 is used in the following applications:

• Used in Darlington pairs to amplify weak signals.
• It can be employed in sensor circuits.
• Driving loads under 500mA.
• Used in audio amplification.
• Used in audio Amplifier Stages.

7. BC548 Physical dimensions

The following diagram shows the physical dimension of the BC548: Recall, BC548 is a bipolar NPN junction transistor and is considered as a current-controlled device where small current at the base is used to control large current at the collector and emitter terminals. Plus, it can drive loads under 500mA and is available in TO – 92 package. That's all for today. I hope you find this read helpful. If you have any question, you can approach me in the section below, I'd love to help you the best way I can. Feel free to keep us updated with your valuable feedback and suggestions. They help us create quality content. Thank you for reading this article.

Introduction to BC546

Hi everyone! Thank you for viewing this article, I welcome you on board. In this post I’ll walk you through the detailed Introduction to BC546. BC546 is a low power NPN transistor mainly used for general purpose amplification and switching applications. In this read you’ll study all nitty-gritty of BC546 transistor i.e. from pinout, pin configuration, and working principle to power ratings, key parameters, physical dimensions and applications. Keep reading.

Introduction to BC546

• BC546 is a bipolar junction NPN transistor that finds applications in switching, amplification, impedance, H-bridge and current mirror circuits.
• This transistor falls in silicon epitaxial planar transistor category which is generally divided into three groups A, B & C. This BC546 is available in group A & B.
• BC546 low power transistor mainly contains three terminals named emitter, base and collector. And all these terminals are different in terms of their doping concentration and are used for external connection with electronic circuits.
• BC546 transistor contains three layers i.e. two N-doped layers and one P-doped layer. The P-doped layer resides between two N-doped layers. Plus, it carries two PN junctions where one is forward biased and other is reverse biased.
• Unlike FET (Field-Effect Transistor) that is voltage controlled device, BC546 is a current controlled device where small current at the base terminal is primarily used for controlling the large current at both emitter and collector terminals.

1. BC546 Datasheet

• Although, we are going to discuss everything related to BC546, in this tutorial but still its always wise to have a look at the datasheet.
• You can download BC546 Datasheet by clicking the below button:

Download BC546 Datasheet

2. BC546 Pinout

BC546 carries three pins named

• Emitter.
• Base.
• Collector.

The collector voltage is much larger than the base voltage and emitter terminal is highly doped compared to base and collector terminals. When voltage is applied at the base terminals, it ignites the electron reaction between emitter and collector terminals.

3. BC546 Pin Configuration

• Emitter current is a sum of both collector current & base current.
• The small current at the base terminal is used to control large current at the emitter and collector terminals.
• This transistor can be employed in three main configurations named:
  • Common base configuration.
  • Common emitter configuration.
  • Common collector configuration.
• Common emitter configuration comes with exact voltage and current ratings required for amplification.
• Forward current defines the nature of amplification. It is called amplification factor, or beta and denoted by ß. Which is a ratio between collector current and base current and it carries no unit. The amplification factor ranges from -110 to 800.
• Similarly, current gain is a ratio between collector current and emitter current. It is known as alpha, denoted by a. The alpha value ranges from 0.95 to 0.99 but more often than not its value is taken as unity.

4. BC546 Working Principle

• BC546 is a junction transistor where both electrons and holes are responsible for conductivity, electrons are majority charge carriers, however.
• In NPN transistor base terminal is positive with respect to emitter and is usually used to control the number of electrons.
• It gets biased and draws current when voltage is applied at the base terminal, thus controlling the large current at emitter and collector side.
• Free movements of electrons plays a key role for conductivity and is mainly used to bridge the gap between emitter and collector where electrons are emitted by the emitter which are then collected by the collector.
• In this NPN transistor current flows from collector to emitter unlike PNP transistor where current flows from emitter to collector.

5. BC546 Power Ratings

Absolute maximum power ratings of this NPN transistor are shown in the figure below:

• Collector-Base voltage is 80V. And Emitter-Base voltage is 6V.
• High Collector-Emitter voltage of 65V makes it the best pick for high voltage audio amplifier applications.
• Collector current is 100mA with maximum power dissipation 500mW at temperature 25C.
• These are stress ratings that, if increased from absolute maximum ratings, can severely affect the quality of the product, thus damaging the device.
• Similarly, if these ratings are applied for the extended period of time, they can affect the device reliability.
• The absolute maximum ratings are stress ratings with values measured at T = 25C

6. BC546 Modes & Key Parameters

The current directions and voltage polarities are opposite in both NPN and PNP transistors. If current flows in a clockwise direction in NPN transistor and carries positive polarity at the base terminal, it will flow in an anticlockwise direction in PNP transistor negative voltage polarity. Flow of electrons from collector to emitter in this NPN transistor depends on the biased voltage applied at the base terminal. Following are four modes of BC546 transistor:

• Active mode.
• Cut-off mode.
• Saturation mode.
• Reverse-active mode.

Base terminal is also called the active mode, and is mainly responsible for transistor action, where voltage is applied that draws small current which is then used to control large current at the emitter and collector terminals. In cut-off mode transistor acts like an open switch and no current flows between the terminals. Saturation mode acts like an ON switch where current flows from collector to emitter. In this condition the voltage difference between collector and emitter is zero. In reverse active mode transistor acts like an active mode but here current direction is reversed, now it flows from emitter to collector.

7. BC546 Alternatives

BC546 contains following alternatives:

• 2SC4145
• 2SD1698
• 2SD1701
• 2SD1978
• 2SD1981
• 2SD2296A
• 2SD2213
• HIT667
• KTC1026
• KTC3200

All transistors mentioned above are NPN transistors and are composed of silicon material. While its complementary types PNP transistors are BC556 & BC559.

8. BC546 Applications

BC546 is mainly used in the following applications:

• It is used in linear amplifiers.
• BC546 finds applications in H-Bridge circuits
• Used for impedance circuits and current mirrors circuits
• Also employed in oscillator circuits and Astable vibrators
• Used in bistable multivibrators and comparator circuits

9. BC546 Physical dimensions

Following diagram shows the physical dimension of BC546: All three terminals are 0.492in in length and 0.181in in width with distance between two terminals 0.142in. This transistor carries weight approx. 0.18g. That's all for today. I hope you’ve got clear idea about BC546 transistor. If you are unsure or have any question, you can ask me in the section below, I'd love to help you the best way I can. You’re most welcome to keep us updated with your valuable feedback and suggestions. Thank you for your precious time.

IR Proximity Sensor Library for Proteus

Hello friends, I hope you all are doing great. In today's tutorial, I am going to share a new IR Proximity Sensor Library for Proteus. Proximity Sensors are not available in Proteus and we are sharing its Proteus library for the first time. So far, I have only shared Proteus Libraries of digital sensors but today I am sharing an analog sensor, so too excited about it. In the next few days, I will keep on sharing Proteus Libraries of different analog sensors, so if you want any sensor in Proteus, then let me know in the comments. IR Proximity Sensors are used to detect hurdles/obstacles placed in their path. They are normally used on robots for path navigation and obstacle avoidance. So, let's have a look at How to download and simulate IR Proximity Sensor Library for Proteus: Note:

• You should also have a look at:
  • Infrared Sensor Library for Proteus.
  • Infrared Tracker Sensor Library for Proteus.

IR Proximity Sensor Library for Proteus

• First of all, download this IR Proximity Sensor Library for Proteus, by clicking the below button:

IR Proximity Sensor Library for Proteus

• It's a .zip file, which will have two folders in it i.e. Proteus Library & Proteus Simulation.
• Open Proteus Library Folder, it will have 3 files, named as:
  • IRProximitySensorTEP.IDX
  • IRProximitySensorTEP.LIB
  • IRProximitySensorTEP.HEX
• Place these three files in the Library folder of your Proteus software.

Note:

• If you are unable to add a Library in Proteus 7 or 8 Professional, then you should have a look at How to add a new Library in Proteus 8.

• After adding these library files, open your Proteus ISIS software, or restart it if it's already open.
• In the component's search box, make a search for IR Proximity.
• If you have installed the Library successfully, then you will get similar results, as shown in the below figure:

• As you can see in the above figure that we have two IR Proximity sensors.
• When it comes to functionality, both sensors are exactly the same, they just have different colors.
• Now simply place these IR Proximity Sensors in your Proteus workspace, as shown in the below figure:

• As you can see in the above figure, I have placed both of these IR Proximity sensors in my Proteus workspace.
• This sensor has 4 pins in total, which are:
  • V ( Vcc ): We need to provide +5V here.
  • G ( Gnd ): We need to provide Ground here.
  • O ( Out ): It's an analog output signal from the sensor.
  • TestPin: It's solely for simulation purposes, we don't have this pin in a real IR sensor.
• As we can't actually place an obstacle in front of this sensor in Proteus simulation, that's why I have used this TestPin.
• If we change the value of TestPin from 0V to 5V then that means the obstacle is coming close.

Adding Sensor's Hex File

• Lastly, we need to add the Sensor's Hex File, which we have downloaded and placed in the Library folder.
• So, in order to do that, right-click on your IR sensor and then click on Edit Properties.
• You can also open the Properties Panel by double-clicking on the sensor.
• Here, in the Properties Panel, you will find Sensor's Hex File Section.
• Click on the Browse button and add IRProximitySensorTEP.HEX file here, as shown in the below figure:

• After adding the Sensor's Hex File, click on the OK button to close the Properties Panel.
• Our IR Proximity Sensor is now ready to simulate in Proteus ISIS.
• Let's design a small circuit, in order to understand the working of this IR Proximity Sensor.

Proteus Simulation of IR Proximity Sensor

• First of all, let's design a simple circuit, where I am attaching a variable resistor with the Test Pin & I am adding a Voltmeter at the Output pin, as shown in the below figure:

• Using this variable resistance, we can change the voltage on Test Pin.
  • If TestPin has 0V, means we don't have any obstacle in front of the sensor.
  • If TestPin has 5V, implies that something's placed right in front of the sensor.
• So, let's have a look at How the output value will change when we change the voltage on TestPin.
• At the Output Pin, I have placed an LC filter, which is also not required in real hardware implementation.
• But I have to use this filter in Proteus Simulation, as Proteus provides the Peak to Peak value and we need to convert that value into Vrms.
• So, if you are working on a real sensor then you don't need to add this inductor or capacitor.
• Now, let's run this Proteus Simulation and if you have done everything correctly, then you will get similar results:

• I have shown three different scenarios in the above figure:
  • In the first image, the variable resistor is at 100%, thus providing 0V at TestPin. That's why we got 0V at Output and hence no obstacle detected.
  • In the second image, the variable resistor is around 50%, thus providing around 2.5V at TestPin. So, we are getting around 2.5V at Output and hence obstacle detected in close range.
  • In the third image, the variable resistor is around 0%, thus providing around 5V at TestPin. So, we are getting around 5V at Output and hence obstacle's just in front of the sensor.
• I have placed this simulation in the above zip file, so play with it and don't forget to add the Sensor's Hex File.

So, that was all for today. I hope this IR Proximity Sensor Library will help engineering students in simulating their course projects. I will interface this IR sensor with Arduino and other Microcontrollers and will share their simulations. If you have any issues, then ask in the comments and I will help you out.

Voltmeter & Ammeter in Proteus ISIS

Hello friends, I hope you all are doing great. In today's tutorial, we will have a look at How to use Voltmeter & Ammeter in Proteus ISIS. It's our 4th tutorial in Proteus series. While designing an electronics project, voltage & current measurements are essential debugging features, as they help in understanding circuit behavior. Proteus has builtin instruments for voltage & current measurement. We have have their probes and today we will discuss them in detail. First have a look at Voltmeter in Proteus ISIS:

How to use Voltmeter in Proteus ISIS

• DC Voltmeter is used to measure the voltage difference across any DC component.
• In order to use DC Voltmeter, we need to click on Virtual Instruments Mode, as shown in the figure.
• In Instruments list, we have DC voltmeter, so click it and place it in your Proteus workspace.
• I am going to use the same circuit, which we have designed in first lecture, shown in below figure:
• As you can see in the figure, I have placed two voltmeters, one at the input and second at the last LED.
• Because of 100kohm resistance, there's a slight drop in the voltage at last two LEDs.
• Moreover, Voltmeters are placed in parallel to these component.

• We can also use Voltage Probe to measure voltage at any point in the electronic circuit.
• So, click on Voltage Probe in the left toolbar and connect it to any point in your circuit and its voltage will be displayed.
• I have placed two Voltage probes on my circuit, as shown in below figure.
• Voltage Probe provides value up to five decimal points, while DC Voltmeter provides value up to 2 decimal points.

• Voltage probes are quite helpful as they are small in size and easy to place in the circuit.

So, that was all about Voltmeter in Proteus. Now, let's have a look at How to use Ammeter in Proteus ISIS:

How to use Ammeter in Proteus ISIS

• DC Ammeter is used to measure the current passing through any DC component.
• We need to click on Virtual Instruments Mode and then click on DC Ammeter.
• Place this Ammeter in series, as shown in below figure:

• We aren't getting any value on our Ammeter as these LEDs are not drawing much current.
• But, you can see we have placed the Ammeter in series, we will use it a lot in coming projects.

So, that was all about How to use Voltmeter & Ammeter in Proteus. I hope you have enjoyed today's tutorial. Till next tutorial, take care & have fun !!! :)