BC327 is a bipolar junction transistor that falls under the PNP transistor family. This transistor is made with silicon material and is a current-controlled device. So this transistor includes three terminals where a small amount of current is produced at one terminal which is used for controlling a large amount of current at the other two terminals. This transistor includes three layers where one N-doped layer is arranged between two P-doped layers. Here, the p-doped layer is charged positively while the N-doped layer is charged negatively. This article provides brief information on the BC327 transistor, pin configuration, working, and its applications.
What is a BC327 Transistor?
The BC327 is a PNP transistor that is mainly used for amplification & switching purposes. This transistor can drive loads below 800mA & is capable of handling load voltage below 45V. This transistor collector dissipation is 625mW & maximum DC current gain is 630, so it can be used in any signal amplification & as an audio amplifier application.
This kind of transistor is manufactured in different versions by various companies. The gain of this transistor may change based on the transistor version. This is a general-purpose transistor where the base of the transistor needs to be linked to the GND to switch ON the transistor.
The BC327 transistor is fabricated in different hFE classifications & can be distinguished by the code number written after the number of transistors. If you discover code number 16 after the transistor number, then the hFE value will be 100 to 250. If this code is – 25 then the hFE value will be 160 to 400. If this code value is – 40 then the hFE value ranges from 250 to 630.
Whenever this transistor is turned off we can notice a positive (+ve) voltage on the base of the transistor. If we measure the voltage between the emitter and the base terminal based on the characteristics of the transistor then a small amount of current needs to flow from the base terminal to switch ON the transistor. Whenever a positive voltage emerges on the base terminal, then leakage current begins to supply from the base terminal to the GND.
Whenever the transistor’s base terminal is connected to the GND, then leakage current begins to flow out from the base to the ground. At the base terminal, the depletion region will start to shrink & more electrons will start migrating from the collector terminal to the emitter & into the circuit so current is constantly supplied throughout the circuit.
The pin configuration of this BC327 transistor is shown below. This transistor includes three terminals which are discussed below.
- Pin-1 (Collector): This terminal collects the electrons that are emitted from the emitter. This terminal is connected to a load
- Pin-2 (Base): This terminal controls the transistor biasing by turning it ON/OFF.
- Pin-3 (Emitter): This terminal emits the electrons into the initial PN junction. This terminal is connected to GND.
Features & Specifications:
The features and specifications of the BC327 transistor include the following.
- This is a PNP transistor including three terminals.
- This transistor is available in the TO-92 package.
- The voltage from the collector terminal to the emitter is -30V to -45V.
- The voltage from the emitter terminal to the base is -5V.
- The saturation voltage from the collector terminal to the emitter is -0.7V.
- The collector current of this transistor is -800mA.
- This transistor’s power dissipation value is 625mW.
- This transistor’s current gain value is 60 to 630hFE.
- The BW transition frequency value of this transistor is 100MHz.
- The junction temperature of this transistor ranges from -55 to 150℃.
- This transistor’s thermal resistance is 200℃/W.
- The o/p capacitance of this transistor is 11pF.
Equivalent and Complementary Transistors
The equivalent BC327 transistors are; 2N4403, BC638, BC488, 2N4402, BC328, BC486 & 2N3702. The BC327 PNP complementary transistors are; BC337 NPN transistors. Replacing a suitable transistor in any circuit based on requirement is very important. To know how to replace it, please refer to this; Replacing Transistors in Electronic Circuits: Factors and Considerations.
How to use BC327 Transistor in a Circuit to Acquire Long-Term Performance?
To use a BC327 transistor in a circuit to get long-term performance, it is suggested not to drive any load above 800mA (0.8A). Use a base resistor to this transistor always and this transistor should not be operated below temperature -55 degrees centigrade > +150 degrees centigrade. Always ensure the pin configuration of the transistor before connecting within the electronic circuit. Connecting a base resistor to the base terminal of the transistor is advisable to avoid it being damaged. Please refer this link for; Choosing Base Resistance for Transistors in Electronic Circuits.
While looking for a suitable transistor for your application based on a few factors, it is very important to look into a few points on How to Select a Transistor.
Anti Bag Snatching Alarm Circuit using BC327 Transistor
An anti-bag-snatch alarm circuit is used with valuable things while traveling. So this simple circuit is arranged within a small portable plastic box and this box is arranged within a bag or handbag.
The required components to make this circuit mainly include; Resistors R1-330K and R2-100R, capacitors C1 is 10nF-63V and C2 is 100uF-25V, transistors Q1 is BC547 and Q2 is BC327, battery B1 is 3V Battery, switch SW1 is a Read Switch and tiny magnet and 8R loudspeaker (SPKR). Connect the circuit as per the simple circuit shown below.
In this circuit, complementary transistors are connected directly as a high-efficiency oscillator to drive a small 8R SPKR. This circuit is powered with a 3V Battery. A small magnet is arranged near the reed switch of the circuit. This is connected to the hand of the bag wearer (or) clothing through a string. When someone attempts to steal your luggage bag suddenly then the magnet will lose contact through the SW1 reed switch.
Once this switch opens, the circuit begins to oscillate & the loudspeaker generates an alarm sound to alert the passenger. Once the alarm goes off the current drawn is about 100mA. Do not provide above 4.5V, the Q2 transistor gets damaged and the circuit will not work. So, a 3V supply voltage is best to work this circuit.
Transistor can be connected to a microcontroller. To know how to interface read on Transistor interfacing to microcontroller.
A few precautions need to be taken before connecting it to the microcontroller. Click on the link to know more about it: Precautions to be taken before connecting a transistor to the microcontroller.
The advantages of BC327 Transistor include the following.
- This transistor uses advanced process technology.
- It has less error voltage.
- Its switching speed is fast.
- It has Full-voltage operation.
- This transistor is capable of handling high power & current.
- This transistor has a wide gain bandwidth.
- It works well at higher frequencies.
- It can also work in both high & low power based applications.
BC327 Transistor Applications
The applications of this Transistor include the following.
- This BC327 transistor is used mainly for amplification & switching purposes within different electronic circuits.
- This transistor is used as a switch to drive up to 800mA of loads like; high power LEDs, relays, transistors, ICs, and many more.
- By using -5V of emitter to base voltage, this transistor is used as the microcontroller o/p to drive up to 800mA of load which can simply drive modules, motors, sensors, and many more.
- These are used in audio amplifiers, pre-amplification stages, push-pull configuration-based circuits, PWM driver circuits, LED dimmer circuits, LED flashers, power amplifiers, microphone preamp circuits, relay drivers, microcontroller driver load, signal amplifiers, PWM-driven applications, flashers/LED dimmers, preamplifier in power amplifier, etc.
Please refer to this link for the BC327 Transistor Datasheet.
Thus, this is an overview of a BC327 transistor which is an epitaxial PNP Si transistor. This transistor will turn on whenever it is connected to the GND & turn off whenever the base terminal is connected directly to 5V. This transistor includes 800mA of collector current, thus it is used easily to drive different heavy loads. Here is a question for you, what is BC337 transistor?