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A1015 Transistor Overview
A1015 Transistor Pinout
A1015 Transistor Specifications
A1015 Transistor Features
A1015 Transistor Equivalent
A1015 Transistor Circuit
Pros and Cons of A1015 Transistor
A1015 Transistor Uses
How to Use A1015 Transistor?
Frequently Asked Questions

A1015 Transistor Equivalent, Datasheet, Pinout, Circuit

Q: What is the equivalent of A1015 transistor?

The A1015 transistor, a PNP BJT. Its common equivalents include: 9015, 2N3906, C1815, BC257, BC307, BC557, and 2N3494.

Q: What is the value of A1015 transistor?

The A1015 transistor offers high stability and reliability with a maximum power dissipation of 200mW, a collector-emitter voltage of -50V, and a collector current of -150mA, making it a practical choice for various electronic circuits.

Q: What is the voltage of A1015?

The A1015 transistor has a collector-emitter voltage (VCEO) of -50V and a collector-base voltage (VCBO) of -50V, with an emitter-base voltage (VEBO) of -5V. These ratings indicate the maximum voltages the transistor can withstand between its terminals under specified conditions.

Q: What is an NPN transistor?

An NPN transistor is a type of bipolar junction transistor (BJT), which is a fundamental semiconductor device used for amplification and switching in electronic circuits. It is characterized by its three-layer structure: two negative (N) regions sandwiching a positive (P) region.

Q: What is the frequency of A1015?

The transition frequency (fT) of the A1015 transistor is typically 80 MHz. This parameter indicates the frequency at which the current gain of the transistor drops to unity (1), and it is an important figure of merit for high-frequency applications.

Q: How do you find the pinout of a transistor?

1.Consult its datasheet for the official pin configuration diagram. 2. Use a multimeter in diode test mode to locate the base (NPN: black probe on base with forward bias; PNP: red probe on base) and measure voltage drops to distinguish emitter/collector. 3. Check physical markings.

Q: How do you connect a PNP transistor to a circuit?

1. Connect to the positive supply voltage (Vcc). 2.Control with a negative voltage (relative to emitter) via a resistor (e.g., pull-down to ground via a switch or microcontroller output). 3.Connect to the load (e.g., LED + resistor), then to ground. 4.The transistor turns on when the base is pulled low, allowing current to flow from emitter to collector.

16 June 2025 1102

Today, we're going to learn about a very common and useful transistor: the A1015. This little device is popular in many electronic circuits, especially where you need to control current using a smaller signal.

This guide will explain everything you need to know about the A1015 transistor. We'll introduce its appearance (package), how to connect it (pinout), its limits (ratings), other transistors like it (equivalents), and some simple circuits you can use it in.

A1015 Transistor Overview

The A1015 transistor is a PNP bipolar junction transistor (BJT) commonly used in low-power electronic applications. Designed primarily for general-purpose amplification and switching tasks, the A1015 is widely found in consumer electronics, audio equipment, and small signal circuits.

PNP: This describes how the transistor is built internally. It means the transistor needs a negative voltage on its "Base" pin relative to its "Emitter" pin to turn on.

Bipolar: This means it uses both electrons (negative charges) and "holes" (places where electrons are missing, acting like positive charges) to conduct electricity inside it.

Junction Transistor: It controls current flow using PN junctions where different semiconductor materials meet.

A1015 Package

The A1015 typically comes in a very common, low-cost package called TO-92. This is a small plastic case with three metal leads (pins) sticking out the bottom. It looks like this:

Shape: Small, plastic, bullet-shaped or slightly rectangular block.

Size: Roughly 5mm long by 4mm wide by 5mm tall–about the size of a pea.

Leads: Three thin metal wires extend down from the bottom (or sometimes the side). These leads are relatively flexible and easy to bend for soldering onto circuit boards or wires.

Markings: The plastic body usually has the text "A1015" printed on its flat side. Sometimes you might also see manufacturer codes or batch numbers.

A1015 Manufacturer

The A1015 is a common PNP bipolar junction transistor (BJT) primarily identified by its electrical specifications, not by a single exclusive manufacturer. Originally developed by Toshiba, it became a widely standardized and cloned "jellybean" part.

Today, numerous semiconductor manufacturers globally produce transistors meeting or exceeding the A1015 specification, including ON Semiconductor, KEC (Korea Electronics), Weitron Technology, UTC (Unisonic Technologies), and Central Semiconductor (CEN), among others. It is packaged almost universally in the low-cost, through-hole TO-92 format, characterized by its small plastic case and three leads.

Its popularity stems from its useful combination of -50V voltage rating, -150mA current capability, high DC current gain (hFE), good availability, and low cost, making it a versatile choice for general-purpose amplification and switching circuits across consumer electronics and hobbyist projects.

A1015 Transistor Pinout

For a transistor in the standard TO-92 package, pin identification depends on the viewing angle. The most common orientation has the flat side facing towards you and the pins pointing downwards:

Pin 1 (Collector - C): Leftmost pin when viewing the transistor with the flat side facing you.

Pin 2 (Base - B): Middle pin.

Pin 3 (Emitter - E): Rightmost pin.

Some manufacturers use a slightly different TO-92 variant. Always check the datasheet for the exact part you are using! However, the "flat side view, left=Collector, middle=Base, right=Emitter" is the most widely used configuration for the A1015.

CAD Model

Symbol

Footprint

3D Model

2D Model

This footprint defines:

Pad Positions: Where the three holes (or copper surface pads) for the transistor's pins will be located on the PCB.

Pad Size & Shape: The size and shape of the copper areas where the pins will be soldered.

Silkscreen Outline: The outline printed on the PCB to show assemblers where to place the component.

Courtyard: A keep-out area indicating how much space around the component must remain free of other parts.

A1015 Transistor Specifications

Parameter	Value
Transistor Type	PNP
Material	Silicon
Polarity	Negative (PNP)
Package Type	TO-92 (Plastic Encapsulated)
Mounting Type	Through-Hole
Complementary Pair	C1815 (NPN)
Collector-Emitter Voltage (Vce)	–50 V
Collector-Base Voltage (Vcb)	–50 V
Emitter-Base Voltage (Veb)	–5 V
Collector Current (Ic max)	–150 mA
Power Dissipation (Pc @25°C)	400 mW
Junction Temperature (Tj max)	150°C
Storage Temperature Range	–55°C to +150°C
DC Current Gain (hFE) @Vce = –6V, Ic = –2 mA	70 to 400
Collector-Emitter Saturation Voltage (Vce(sat)) @ Ic = –100 mA, Ib = –10 mA	–0.3 V
Base-Emitter On Voltage (Vbe(on))	–0.6 to –0.7 V
Collector Cutoff Current (Ices) @ Vce = –50 V	≤ –0.1 μA
Base Cutoff Current (Iebo) @ Veb = –5 V	≤ –0.1 μA
Transition Frequency (fT) @ Vce = –6 V, Ic = –1 mA	80 MHz (typical)
Lead Forming	Straight or kinked
Pin Configuration (viewed flat side facing)	1 = Emitter, 2 = Collector, 3 = Base
Package Dimensions	~4.5 mm (width) × 4.0 mm (height) × 3.5 mm (depth)

Absolute Maximum Ratings (Ta = 25°C)

(Exceeding these values may cause permanent damage to the device.)

Parameter	Symbol	Rating	Unit	Notes
Collector-Base Voltage	V_CBO	-50V	V	Voltage between Collector-Base (Emitter open)
Collector-Emitter Voltage	V_CEO	-50V	V	Voltage between Collector-Emitter (Base open)
Emitter-Base Voltage	V_EBO	-5V	V	Voltage between Emitter-Base (Collector open)
Collector Current	I_C	-150mA	mA	Continuous current (negative for PNP)
Base Current	I_B	-50mA	mA	Maximum base current
Total Power Dissipation	P_tot	400mW	mW	At 25°C ambient temperature
Junction Temperature	T_j	150°C	°C	Maximum operating temperature
Storage Temperature	T_stg	-55°C to +150°C	°C	Non-operating range

A1015 Transistor Features

PNP Type: Complementary to popular NPN transistors like the C1815. Often used together for push-pull outputs or complementary symmetry amplifiers.

Low Voltage, Medium Current: Well-suited for circuits powered by common voltages (5V, 9V, 12V) and currents up to around 100-150mA.

High DC Current Gain (hFE): Offers good amplification capability for a small base current, especially useful in signal amplification stages. The typical gain is often over 100, sometimes much higher.

Moderately Fast Switching Speed: The 80MHz allows it to be used in audio amplifiers, simple switching power supplies, and logic level converters (though not for super high-speed digital circuits).

Low Collector-Emitter Saturation Voltage: Typically around -0.25V at high current. This means minimal power is wasted as heat when fully switched "ON", making it efficient for switching.

TO-92 Package: Inexpensive, compact, and easy to solder manually. Ideal for hobbyists and cost-sensitive mass production.

Widely Available: Produced by numerous manufacturers globally, making it easy and cheap to source as a component.

Good Linearity (for a BJT): Its gain is reasonably stable over its operating range, making it suitable for analog amplification (especially in the middle of its operating curve).

Electrical Characteristics

Parameter	Symbol	Test Conditions	Min.	Typ.	Max.	Unit
Collector Cutoff Current	I_CBO	V_CB = –50V, I_B = 0	–	–	–0.1	µA
Emitter Cutoff Current	I_EBO	V_EB = –5V, I_C = 0	–	–	–0.1	µA
DC Current Gain	hFE	V_CE = –6V, I_C = –2 mA	70	–	400	–
Collector-Emitter Saturation Voltage	V_CE(sat)	I_C = –100 mA, I_B = –10 mA	–	–0.1	–0.3	V
Base-Emitter Saturation Voltage	V_BE(sat)	I_C = –100 mA, I_B = –10 mA	–	–0.6	–1.2	V
Base-Emitter On Voltage	V_BE(on)	V_CE = –6V, I_C = –2 mA	–	–0.67	–0.7	V
Transition Frequency	fT	V_CE = –6V, I_C = –1 mA	–	80	–	MHz
Output Capacitance	C_ob	V_CB = –10V, f = 1 MHz	–	3	6	pF

A1015 Transistor Equivalent

Equivalent Transistor	Polarity	V_CE (Max)	I_C (Max)	hFE Range	Package	Notes
2N2907	PNP	–60 V	–600 mA	100–300	TO-92	Higher current capacity
BC558	PNP	–30 V	–100 mA	110–800	TO-92	Slightly lower V_CE
S9015	PNP	–50 V	–100 mA	100–300	TO-92	Very close specs
2SA733	PNP	–50 V	–150 mA	70–400	TO-92	Almost identical; same pinout
2N5401	PNP	–150 V	–600 mA	30–100	TO-92	Higher voltage, lower gain
KSA1015	PNP	–50 V	–150 mA	70–400	TO-92	Direct replacement; same specs

A1015 Complementary NPN transistor

The A1015 is a PNP transistor, and its complementary NPN counterpart is typically the C1815. Complementary transistor pairs are designed to have mirror-like electrical characteristics, enabling them to work together in push-pull amplifier circuits, audio stages, and signal switching applications.

PNP Transistor	NPN Complement	Polarity	V_CE (Max)	I_C (Max)	hFE Range	Package	Application Use
A1015	C1815	PNP / NPN	±50 V	±150 mA	70–400	TO-92	Low power amplification, switching
2SA733	2SC945	PNP / NPN	±50 V	±150 mA	70–400	TO-92	General-purpose analog circuits
BC558	BC548	PNP / NPN	±30 V	±100 mA	110–800	TO-92	Audio frequency amplifier stages
S9015	S9014	PNP / NPN	±50 V	±100 mA	100–300	TO-92	Small signal amplification

Replacement Considerations

Check the Pinout

Verify Key Ratings

Gain

Frequency Response

Saturation Voltage

A1015 Transistor Circuit

Circuit Symbol

Arrow: The arrow on the emitter (E) always points IN towards the base (B) for a PNP transistor. (For NPN, it points out). This arrow shows the direction of conventional current flow when the transistor is active in its normal mode.

Circle: The circle around the symbol is often included, but sometimes omitted in simpler schematics.

Circuit Diagram Examples

Simple Switch (Driver for an LED or Relay)

This circuit shows how to use the A1015 as an electronic switch, controlled by a small signal (like from a microcontroller GPIO pin or a switch).

How it Works (Active Low)?

When the control input (base connected via R2) is HIGH (close to +Vs voltage), no current flows from the base to ground. The transistor is OFF. No current flows from Emitter to Collector. The load (LED) is OFF.

When the control input is pulled LOW (close to 0V/GND), current flows from +Vs, through resistor R1 (if present), into the Base, down through R2, to GND. This base current (IB) "turns on" the transistor.

A much larger current can now flow from +Vs (Emitter), through the transistor (Collector), and through the load (LED/Relay) to GND, turning the load ON. The ratio R2/R1 controls IB, ensuring it's enough to saturate the transistor without exceeding limits.

Simple Amplifier (Common Emitter):

This basic circuit amplifies a small input signal voltage.

How it Works?

Resistors Rb1 and Rb2 form a voltage divider to set a fixed Base bias voltage (around 1-2V below Vcc for PNP). This establishes the operating point (quiescent point - Q-point).

Re provides negative feedback, stabilizing the operating point against temperature changes and manufacturing variations.

Capacitor C1 blocks DC from the input source but allows the AC signal (Vin) to pass through to the base.

The small AC input signal voltage variation (Vin) at the base causes a much larger corresponding variation in the current flowing through the transistor (thanks to hFE).

This varying current flows through Rc. The varying voltage across Rc creates the amplified output signal (Vout) taken between Collector and GND (or Vcc, depending on bias point).

C2 (if used) bypasses Re for the AC signal, increasing the available gain by reducing AC negative feedback. Dc biasing is still stabilized by Re.

The voltage gain (Vout / Vin) is roughly - (Rc / Re) (ignoring C2 and transistor impedance). The gain is negative meaning the output signal is inverted (180° phase shift) relative to the input.

Pros and Cons of A1015 Transistor

Pros:

Inexpensive: Very low cost per unit.

Readily Available: Easy to find in electronics stores and online distributors worldwide.

Simple to Use: Only three pins, straightforward biasing for basic switching and amplification.

Good Gain: High hFE allows significant current amplification with small base currents.

Low Saturation Voltage: Efficient when used as a switch.

Versatile: Suitable for both switching and amplification in low/moderate power circuits.

Decent Frequency Response: Adequate for audio frequency applications and moderate-speed switching.

Standard Package: TO-92 is universal and easy to solder.

Cons:

Limited Power Handling: Max power dissipation of 400mW restricts it to low/moderate current applications (usually << 150mA continuous).

Wide Gain Spread: The wide hFE range (70-400 or more) means circuit performance can vary significantly between individual transistors. Designs need tolerance for this variation.

Not the Fastest: Slower than dedicated switching transistors or FETs (though fine for many applications).

Negative Voltages (Conceptually): Working with PNP devices can be slightly less intuitive for beginners compared to NPNs, as "on" requires pulling the base negative relative to the emitter. This often translates to controlling the base with a signal referenced to the positive rail (like in the switch example).

Temperature Sensitivity: Like all BJTs, performance (especially VBE and hFE can change with temperature.

A1015 Transistor Uses

General Purpose Amplification: Audio pre-amplifiers, microphone preamps, small signal gain stages in radios and instrument circuits.

Switching Loads:

Driving LEDs (especially as high-side drivers).

Controlling relay coils.

Switching buzzers or small speakers.

Switching solenoids or small motors (within current limits).

Logic Level Conversion: Often used in simple circuits to interface between microcontrollers (5V/3.3V logic) and higher voltage devices.

Push-Pull Output Stages: Paired with an NPN transistor (like C1815) in the output stage of audio power amplifiers (small speakers, headphone amps) or motor drivers to provide both push and pull capability efficiently.

Complementary Symmetry Amplifiers: Common topology where pairs of PNP (like A1015) and NPN transistors are used for efficiency and power output.

Current Sources/Sinks: Simple circuits providing a relatively constant current to another component (like biasing an LED or charging a capacitor).

Hobbyist Projects: A staple component in Arduino, Raspberry Pi, and general electronics projects due to cost and availability.

How to Use A1015 Transistor?

1

Identify the Pin Configuration
The A1015 transistor comes in a TO-92 package. When the flat side faces you and the pins point downward, the pins are (from left to right): Emitter – Collector – Base. Knowing the pinout is essential before making any connections in a circuit.
2

Understand the Function of Each Pin

Emitter (E): Connected to the positive supply in PNP configuration.

Collector (C): Connects to the load and then to ground.

Base (B): Acts as the control terminal—current flows out of the base to turn the transistor ON.

3

Choose an Application (Switching or Amplification)
Decide whether you’re using the A1015 as a switch (on/off control of devices like LEDs or relays) or as an amplifier (to boost weak analog signals such as audio). This choice determines how you bias and connect the transistor.
4

Bias the Base Properly
Use a resistor (typically 1kΩ to 10kΩ) between the base and ground (for PNP) to control current flow. When the base voltage is at least 0.6–0.7V lower than the emitter, the transistor turns ON, allowing current to flow from emitter to collector.
5

Connect the Load
Place your load (e.g., LED, speaker, relay) between the collector and ground. When the transistor is ON, current will flow from the emitter, through the load, to ground—thus powering the load.
6

Test the Circuit
Power the circuit and apply control signals to the base. If you're using the A1015 as a switch, pulling the base low (toward ground) should turn the load ON. In amplifier mode, you should see a larger output signal at the collector relative to the small input at the base.
7

Fine-Tune Resistor Values (Optional)
To optimize performance, adjust base and collector resistor values based on your load and desired gain or switching speed. Always ensure you stay within the transistor’s limits: Vce ≤–50V, Ic ≤–150mA.

Whether you're replacing one in an old radio, incorporating it into a new project based on a schematic you found, or learning about transistor fundamentals, knowing the A1015's pinout, specifications, equivalents, and typical circuit applications is essential.

By carefully identifying the pins, calculating the correct base resistor for switching, and staying within its electrical limits, you can successfully harness the power of this versatile PNP workhorse.

Frequently Asked Questions

What is A1015 transistor used for?

The A1015 transistor is a PNP bipolar junction transistor (BJT). It is widely used in audio amplification, signal switching, darlington pair configurations, voltage regulation, oscillator circuits, battery-powered devices, educational and hobby projects.

What is the equivalent of A1015 transistor?

The A1015 transistor, a PNP BJT. Its common equivalents include: 9015, 2N3906, C1815, BC257, BC307, BC557, and 2N3494.

What is the value of A1015 transistor?

The A1015 transistor offers high stability and reliability with a maximum power dissipation of 200mW, a collector-emitter voltage of -50V, and a collector current of -150mA, making it a practical choice for various electronic circuits.

What is the voltage of A1015?

The A1015 transistor has a collector-emitter voltage (VCEO) of -50V and a collector-base voltage (VCBO) of -50V, with an emitter-base voltage (VEBO) of -5V. These ratings indicate the maximum voltages the transistor can withstand between its terminals under specified conditions.

What is an NPN transistor?

An NPN transistor is a type of bipolar junction transistor (BJT), which is a fundamental semiconductor device used for amplification and switching in electronic circuits. It is characterized by its three-layer structure: two negative (N) regions sandwiching a positive (P) region.

What is the frequency of A1015?

The transition frequency (fT) of the A1015 transistor is typically 80 MHz. This parameter indicates the frequency at which the current gain of the transistor drops to unity (1), and it is an important figure of merit for high-frequency applications.

Is A1015 PNP or NPN?

The A1015 transistor is a PNP bipolar junction transistor (BJT) If you're working on a circuit that requires a PNP device for amplification or switching, the A1015 is a suitable choice.

How do you find the pinout of a transistor?

1.Consult its datasheet for the official pin configuration diagram. 2. Use a multimeter in diode test mode to locate the base (NPN: black probe on base with forward bias; PNP: red probe on base) and measure voltage drops to distinguish emitter/collector. 3. Check physical markings.

How do you connect a PNP transistor to a circuit?

1. Connect to the positive supply voltage (Vcc). 2.Control with a negative voltage (relative to emitter) via a resistor (e.g., pull-down to ground via a switch or microcontroller output). 3.Connect to the load (e.g., LED + resistor), then to ground. 4.The transistor turns on when the base is pulled low, allowing current to flow from emitter to collector.

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Liam Carter

Liam Carter is an accomplished Senior Electronic Engineer with over a decade of expertise in the design, development, and optimization of core electronic components. His career has focused on pioneering advancements in semiconductor devices, including precision resistor networks, high-frequency transistor architectures, and innovative IC packaging solutions. With extensive experience in circuit simulation, failure analysis, and thermal management strategies, he has successfully led cross-functional teams in delivering robust electronic systems for industrial automation and IoT applications. His technical leadership in material selection, signal integrity validation, and miniaturization techniques has consistently elevated product performance while reducing manufacturing costs, solidifying his reputation as a forward-thinking innovator in electronic component engineering.