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| university:courses:engineering_discovery:lab_11 [19 Oct 2016 17:28] – [Procedure] Jonathan Pearson | university:courses:engineering_discovery:lab_11 [19 Oct 2016 21:12] – [Procedure] Jonathan Pearson | ||
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| The current gain and low output impedance of the emitter-follower amplifier make it ideal for driving low impedance loads, which may be DC- or AC-coupled. | The current gain and low output impedance of the emitter-follower amplifier make it ideal for driving low impedance loads, which may be DC- or AC-coupled. | ||
| ==== Objective ==== | ==== Objective ==== | ||
| - | To design, build, and test an emitter-follower amplifier using a 2N3904 NPN transistor, with an input resistance of at least 1 KΩ that is capable of driving an AC-coupled 47 Ω load with a 2 V< | + | To design, build, and test an emitter-follower amplifier using a 2N3904 NPN transistor, with an input resistance of at least 1 KΩ that is capable of driving an AC-coupled 47 Ω load with a 1 V< |
| ==== Materials and Apparatus ==== | ==== Materials and Apparatus ==== | ||
| * Data sheet handout for the 2N3904 NPN transistor | * Data sheet handout for the 2N3904 NPN transistor | ||
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| - Disable “Repeated Sweep” mode; waveforms can be paused for analysis | - Disable “Repeated Sweep” mode; waveforms can be paused for analysis | ||
| - Set up the M1K to source voltage/ | - Set up the M1K to source voltage/ | ||
| - | - Set up Channel A source waveform for a 100 Hz “Sine” output that swings between 2.0 V and of 4.0 V | + | - Set up Channel A source waveform for a 500 Hz “Sine” output that swings between 2.5 V and 3.5 V |
| - | - Observe the output voltage into the 1 KΩ load resistor on Channel B and verify that it is swinging nominally +/- 1 V about the 2.5 V baseline and that it is in-phase with the input signal | + | - Observe the output voltage into the 47 Ω load resistor on Channel B and verify that it is swinging nominally +/- 0.5 V about the 2.5 V baseline and that it is in-phase with the input signal |
| - | - Observe the voltage at the emitter on Channel B and verify that it is swinging nominally +/- V about a 1.7 V bias voltage and that it is also in-phase with the input signal. | + | - Observe the voltage at the emitter on Channel B and verify that it is swinging nominally +/- 0.5 V about a 1.7 V bias voltage and that it is also in-phase with the input signal. |
| - Note any visible distortions in the output signals | - Note any visible distortions in the output signals | ||
| - Remove the input signal and measure the DC bias voltages at the base, emitter, and collector, and verify that these are at their designed levels, allowing for resistor tolerances | - Remove the input signal and measure the DC bias voltages at the base, emitter, and collector, and verify that these are at their designed levels, allowing for resistor tolerances | ||
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| - Remove the AC-coupling capacitor and bias resistors from the amplifier input and connect it to the output of the CE amplifier from the "Class A NPN Common-Emitter Amplifier" | - Remove the AC-coupling capacitor and bias resistors from the amplifier input and connect it to the output of the CE amplifier from the "Class A NPN Common-Emitter Amplifier" | ||
| - Refer to the illustration below for one way to interconnect the two amplifiers on the solderless breadboard{{ university: | - Refer to the illustration below for one way to interconnect the two amplifiers on the solderless breadboard{{ university: | ||
| - | - Verify that the voltage across the 47 Ω load resistor is swinging +/- 1V about the 2.5 V bias voltage | + | - Verify that the voltage across the 47 Ω load resistor is swinging +/- 0.5V about the 2.5 V bias voltage |
| - Calculate the rms power dissipation in the load resistor | - Calculate the rms power dissipation in the load resistor | ||
| - Estimate the voltage swing that would be present across the 47 Ω load resistor if it were driven by the CE stage alone, without the emitter-follower buffer in place | - Estimate the voltage swing that would be present across the 47 Ω load resistor if it were driven by the CE stage alone, without the emitter-follower buffer in place | ||
university/courses/engineering_discovery/lab_11.txt · Last modified: 03 Jan 2018 19:38 by Doug Mercer