Lesson 01

What is Transistor

animation

Interactive Electronics Trainer

What is Transistor - Interactive Simulation

A transistor is a semiconductor device that uses a small base current to control a larger collector current. It can work as a switch or as an amplifier.

Base Voltage

9

V

Base Current

0

mA

Collector Current

0

mA

Lamp Power

0

mW

Control Panel

Lower base resistance increases base current.

Lower resistance allows more collector current.

Transistor Rule

Ic ~= Beta x Ib

0mA ~= 100 x 0mA

Bias Low: minimum 0.2mA base current needed.

Transistor Switch Circuit Visualizer

Reference transistor switch circuit for basic switching behavior.

TRANSISTOR OFFLEVEL: OFF
10k300BASECOLLECTOREMITTER

Base

Minimum bias current: 0.2 mA.

0 mA

Collector

Load current flows through the collector path.

0 mA

Load Lamp

The lamp glows when the transistor turns on.

0% Glow

Transistor Indicators

Switching State

0%

The transistor will not turn on until minimum base bias current is reached.

Base Bias Level

0%

Conduction starts once the base current crosses the minimum bias level.

Current Amplification

0%

Collector current is controlled by the current gain beta.

Lamp Brightness

0%

More collector current makes the lamp brighter.

Control Efficiency

0%

Without base bias, the output control path stays inactive.

Transistor Level

OFF

OFFWEAKACTIVESAT

What is Transistor?

Definition

A transistor is a three-terminal semiconductor device: Base, Collector, and Emitter. It is commonly used as a switch or an amplifier.

Working Principle

A small current into the base can make the collector-emitter path conductive, allowing a larger load current to flow.

Learning Insight

Switch Mode

With a base signal, the transistor turns on. Without it, the transistor stays off.

Amplifier Mode

It can turn a small input signal into a larger output signal.

Current Limiting

Without a base resistor, excessive base current can damage the transistor.

Calculation test cases
[
  {
    "name": "switch off base current",
    "switchOn": false,
    "voltage": 9,
    "resistance": 10000,
    "gain": 100,
    "load": 300,
    "expectedBaseCurrent": 0,
    "expectedLevel": "OFF"
  },
  {
    "name": "9V through 10k base resistor",
    "switchOn": true,
    "voltage": 9,
    "resistance": 10000,
    "gain": 100,
    "load": 300,
    "expectedBaseCurrent": 0.0009
  },
  {
    "name": "minimum bias current required",
    "switchOn": true,
    "voltage": 3,
    "resistance": 50000,
    "gain": 100,
    "load": 300,
    "minimumBiasCurrent": 0.0002,
    "expectedTransistorOn": false,
    "expectedLevel": "CUT-OFF"
  },
  {
    "name": "collector current is limited by load",
    "switchOn": true,
    "voltage": 9,
    "resistance": 10000,
    "gain": 200,
    "load": 300,
    "expectedMaxCollectorCurrent": 0.03,
    "expectedLevel": "SATURATION"
  },
  {
    "name": "base resistance slider affects base current",
    "switchOn": true,
    "voltage": 9,
    "resistance": 5000,
    "gain": 100,
    "load": 300,
    "expectedBaseCurrent": 0.0018
  }
]