The Engineering Projects

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.