<^< Direct Coupled Amplifier | Course Index | Transistor Amplifier Circuits >^>
| Objective:
| To investigate a direct coupled amplifier
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| Underpinning knowledge:
| Operational amplifier symbols and connections
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| Apparatus:
| TINA circuit file, or apparatus to make the following circuit.
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| TINA Circuit File:
| Click here to download circuit file
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| Initial Settings:
| Vin = 1V at 1kHz, RIN = 100kΩ, RF = 500kΩ.
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| Requires:
| Paper, Linear graph paper, pen or pencil.
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| Instructions:
(a) Set Vin = 1V at 1 kHz
(b) Set RIN = 100kΩ, RF = 500kΩ
(c) Select 'AC conditions'
(d) Observe the output waveform produced by the amplifier. Sketch two complete cycles of the output waveform and include labelled axes of voltage (Vout) and time (t).
(e) Repeat (d) for RF = 1MΩ and RF = 2MΩ.
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Observations:
(a) Comment on the waveforms produced. Do these indicate a phase inversion?
(b) Show that the voltage gain, AV, of the amplifier is given by: AV = -RF/RIN
(c) Explain what happened when RF = 2MΩ. What caused the distortion in the output waveform?
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| Further work:
Design an inverting amplifier with a voltage gain of 40 and an input resistance of 20kΩ. Sketch the circuit diagram for the amplifier showing the component values. Test the amplifier using TINA and verify that a voltage gain of 40 is achieved.
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<^< Direct Coupled Amplifier | Course index | Transistor Amplifier Circuits >^>
