Waveform tests 1. Connect the Pico-scope AWG as indicated in circuit below: R2 1kΩ R1 1.5k +9V AWG Chopped sinewave 1 Vpk, 50Hz OP1 R3 1000 -9V LED 2. Use the Pico-scope AWG to simulate triac delay angles of 30° and 150°, apply these to the LED and observe the LED brightness. (N.B. see the video on how to generate the waveforms)
3. Use a second view window in pico-scope to view harmonics and obtain the ratios V13/V_1 for delay angles of 60°, 90° and 120°. Tabulate your results (table 1.2 below) and compare with theoretical predictions. These predictions were evaluated by using the above expressions. able 1.2: Harmonic content versus delay angle Delay angle (degrees) 60° 90° 120° Theoretical value of V3/VLI 0.285 0.537 0.773 Measured value of V23/VLI Jhere: V13 rms value of third harmonic component of the lamp voltage. = rms value of the fundamental component of the lamp voltage. VL1 Comment on the 3 harmonic values readings you have recorded: Which one has the greatest distortion i.e. ratio of V23/VLI?
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