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Worksheet: Transistor as a Current Amplifier

<^< Transistor as a Current Amplifier | Course Index | Transistor as a Switch >^>

Objective: To investigate the operation of a transistor as a simple current amplifier.
Underpinning knowledge: Semiconductors. Transistors. Current gain. Amplifiers.
Apparatus: TINA circuit file, or apparatus to make the following circuit.
TINA Circuit File: Click here to download circuit file
Initial Settings: Base voltage supply = 5V. Collector voltage supply = 5V. Base input resistance (R1) = 10kΩ. Collector load resistance (R2) = 220Ω.
Requires: Paper, Linear graph paper, pen or pencil.
Instructions:

(a) Measure and record in a table values of collector current (IC) at each of the following input voltages; 0V, 1V, 2V, 3V, 4V, 5V, 6V, 7V, 8V, 9V, and 10V.

(b) Plot a graph to show the variation of collector current (IC) with input voltage.

(c) Identify the linear range on the graph and determine the slope of this line (mA / V).

Observations:

Comment on the shape of the graph produced and the extent of the linear part of the graph. Within what range should the input voltage be to ensure linear operation? If the input voltage was to change from 2V to 4V what change in collector current would be produced? Would the collector voltage (VCE) fall or rise as a result?

Further work:

Investigate the operation of the circuit (and again measure the slope of the graph) for two other types of silicon transistors. Compare the results with those of the 'ideal' transistor.

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Page last modified on July 29, 2011, at 08:58 AM