Syed M Raza
Graduate of Columbia University & Fordham University
Photoresistor Controlled Phasers
Summary:
My team and I implemented a phase shifter. A phase shifter is an audio effect that changes the timing of different parts of a sound wave. It does this by splitting the original sound into two parts, shifting the timing of one part slightly, and then combining the two parts back together. This creates a unique “swooshing” or “whooshing” effect that can add depth and interest to the sound.
LT Spice Simulations:
Before configuring the real circuit, my team & I ran several LTSpice simulations. The schematic shows four phaser circuits in series with each other. In each of these phaser circuits, the op-amp is configured to function as an inverting uniform buffer when a DC signal is fed through the inputs because the capacitor connected on the positive terminal of the op-amp works like an open circuit. Large 10kΩ resistances were chosen for stability.
Experimental Results:
In the photos attached below, we can see the changes that occur when we adjust the frequency generator. We see the phasing that takes place, which is our objective in this laboratory. The green trace is the input from the function generator and the yellow trace is the phased output from our circuit.
In the next photo, we are able to take a look at what we are feeding in our LED. In this part of the experiment, we can see it is oscillating at a frequency of around 450 HZ, but in the square waveform. This is different from the input function generator.
