PhysicsChapter 9: Electronics
Transistor As A Switch and Amplifier
Introduction
A transistor has two especially important uses in electronic circuits: 1. Switching 2. Amplification
Definition
Transistor as a Switch
A transistor can be operated between states where the collector-emitter path carries very little current and where it conducts strongly. This makes it useful as an **electronic switch**. A small input at the base can therefore control a larger load current.
Transistor as an Amplifier
A small variation in the input signal can control a larger variation in the output circuit. This is called **amplification. The extra output energy does not come from the transistor itself. It comes from the external power supply**. The transistor controls this energy according to the input signal.
Applications
Switching: * digital circuits; automatic controls; sensor circuits. Amplification: * audio circuits; communication equipment; sensor signals.
Exam preparation
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Review the key facts, formulas and checks before you move on.Transistor As A Switch and Amplifier
Sticky Notes · Quick Revision
TRANSISTOR
- Small input
- ↓
- Controls larger current
USES
- Switch + Amplifier
60-second revision
- Switch → controls ON/OFF states.
- Amplifier → small signal controls larger signal.
- Energy → external supply.
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