Connect the red banana plug to the second Harmonic 1 OUTPUT banana jack. Connect the black banana plug of the other BNC lead to the 10K Output Ground banana jack.Connect the trigger cable from the TRIGGER OUTPUT of the synthesizer (GND tab to the black banana jack) to ANALOG CHANNEL A BNC adapter.Press the RESET button on the synthesizer to initialize all of the internal oscillators to be in phase.Turn on the power to the Fourier synthesizer.In addition, Channel A of the 850 interface must be connected to the trigger output of the synthesizer so that the changes in phase may be observed. Note that the summing amplifier introduces a phase shift of 180° from the displays of the the individual harmonics. The output of the summing amplifier may also be displayed. the output of the harmonics may be displayed one-by-one on Channel B of a the Pasco 850 Interface through the use of the individual output jacks. These amplitudes must be set by oscilloscope measurement of the amplitude of each harmonic (not by the crude scales on the synthesizer knobs). If any of the signals appear out-of-phase with the rest, pushing the reset button will bring it in-phase.įor the synthesis of square waves, only odd harmonics are required. To correctly observe the phase relationships between fundamentals and harmonics, the external trigger on the oscilloscope must be connected to the trigger output of the synthesizer.
This is important when synthesis of complex (e.g., a square) waveform is attempted. The summing amplifier introduces its own phase shift of 180°, so that positive cosine is produced at the output of the summing amplifier as opposed to the individual minus cosines at the input. The fundamentals and all harmonics can be switched into a summing amplifier, where they are added and sent to a high impedance BNC jack for display on an oscilloscope and to an audio amplifier and speaker with a separate volume control for listening. When all of the controls are set to zero, the individual output jacks produce (minus) cosine waves.
The phase controls consist of 90° and 180° switches and a -90° to +90° knob.
The Fourier synthesizer generates a fundamental sinusoidal signal of 440 Hz (concert A) and eight harmonics:Įach harmonic has a separate output jack for connection to an oscilloscope, as well as separate phase and amplitude controls.
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