Lab 1: Putting it all together

We now have an oscillator and a switching mechanism to power a speaker based on some information logic. We may now combine them to turn the oscillating information signals coming from the timer circuit into a sound emanating from the speakers. As a quick note, this alternation is necessary, as if a constant voltage was applied to the speaker, the voice-coil would move to a single position. However, if this signal is turned on and off, the the position of the coil (and therefore the woofer) will alternate between rest and the position at which the "solenoid" of the voice-coil moves the woofer. This alternation creates waves in the air which vibrate in our ears, sending neural spikes into our brain, and these spikes in the brain miraculously are experiences as the aforementioned pretty pretty music.

Of course, sometimes, especially at the frequencies coming out of our speaker, it was more closely experienced simply as "spikes" in the brain.

Although we believe we could wire the output information signal directly to the base of the transistor, it seemed a good idea to keep some of the functionality of the two mechanical switches we wired up in the first part of the experiment and use one of them as an on/off switch. We therefore had two options for our final circuit. In one version, the output of the timer circuit was plugged into the base of the transistor, and the logic was taken completely out. In another, we supply the timer output as one of the switched inputs in our mess of nor-gates so that the circuit needs both a mechanical switch and a high output from the timer to turn on the speaker.


This seems a bit wasteful of an oscillating circuit that is working itself to death, even if the circuit is switched off and the speaker is not moving, but our final design represents only one possibility for a combination of the two circuits. In further labs, we will have more detailed requirements for the circuits and so a combination more fitting to that specific task may emerge.