Lab Report 6

Experiment

Our experiment for this week was to build a voltage controlled square wave oscillator using a schematic given to us in class. Most of us didn't have much experience working with schematics, so the main challenge for us was figuring out how the circuit should actually look on our breadboards. I finally figured it out after a very frustrating half-hour, and here is the final result. The variable resistor controls the frequency of the oscillator.

The next step was to add a switch in between the output of the 555 timer and the audio output. This made it so the signal only went to the output when the button was pressed.

We also made circuits where the button bypassed the signal to ground. This made it so the signal was cut when the button was pressed. I forgot to take a picture of this, but it was basically the same circuit as above, just with a wire running from the button to ground.

Lastly, we added another potentiometer, but this time it was affecting the pan of the signal. The signal was routed into the middle connection on the potentiometer, and the left and right outputs were routed to their corresponding sides. This created a pretty solid panning effect.

Questions

1. For me at least, the most difficult aspect of working with the schematic was keep track of the wire paths. There were a few connections that were also connected to power, but since the power source symbol was in the corner of the diagram, it was easy to miss. It's just a matter of visualizing what the connections actually have to look like, since we are basically told what the wires need to be connecting, but not how to concretely achieve those connections.

2. You would use a peak follower, which we made in the last lab, then output that voltage to the 4th input on the timer (I think), and you would get rid of the variable resistor and use a set resistance. I'm not entirely sure, but you would have to use the output voltage of a peak follower to change the oscillator frequency, and it seems like the 4th and 5th inputs on the timer dictate the frequency.

3. I think you would have the incoming signals wired to the left and right terminals of the potentiometer, then have the center terminal connected to the audio output. This would be affecting the resistance for each audio input.

Final Project

1. Drum controller. Uses multiple piezo disks and pressure sensors to detect pressure and location of finger on control surface and then outputs voltage to an oscillator and filter.

2. Piezo and pressure sensors, speaker, voltage controlled oscillator (maybe 2 or 3 depending on how many control surfaces I want to have), voltage controlled filter (possible multiple), control surface (I was thinking a wooden bowl).

3. I will probably have to buy materials to make multiple oscillators and filters, the control surface (which I haven't fully figured out yet), and some sort of speaker set-up.