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How to Bias Transistors

Electrcity is created from the flow of sub-atomic particles known as electrons. An electrical circuit consists of a number of interacting components such as resistors, capacitors and transistors. The transistor is arguably the most important such component since it enables the switching and amplification of electrical currents. There are several types of transistors but they all require the application of one or more voltages (bias) in order to function correctly. The application of a bias can be achieved using a DC power supply.

Things You'll Need

DC power supply
BC182 transistor
Electrical wire
Electrical switch
470 Ohm resistor
10 kOhm resistor
Breadboard

Instructions

- 1
  Mount the transistor on a piece of electrical breadboard. Transistors have three electrical connectors and these are labelled the emitter, base and collector. These are labelled on the transistor as "e", "b" and "c". There are many ways to bias a transistor. The simplest of which allows the transistor to act like a switch.
- 2
  Connect a light emitting diode and 470 ohm resistor in between the positive terminal of the DC power supply and the collector terminal of the transistor.
- 3
  Connect a 10k ohm resistor to the base terminal of the transistor. Connect an electrical switch in series with the 10k ohm resistor and connect the other side of the switch to the positive terminal of the DC power supply. The 10k ohm resistor is important is prevents damage to the transistor.
- 4
  Connect the emitter terminal of the transistor to the 0V terminal of the power supply. The connections to the simple testing circuit is now complete.
- 5
  Switch on the DC power supply and set a voltage of +9V. When the switch is pressed, the LED light should come on, demonstrating that the transistor is biased and working.

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