Mon. Week 11, May 5: Intro to Electronics

The subject of this day's lecture and lab was that of electronics, more specifically, the diode and the transistor. The diode is a component made up of two layers of a semiconductor material that has been doped with elements that give one of the layers a significant amount of free electrons and the other layer a significant amount of electron holes. When these two layers are brought into contact, the free electrons and holes combine and create what is know as the depletion region. If voltage is applied in one direction, the region shrinks and the diode acts as a conductor, but when voltage is applied in the reverse direction, the region grows and becomes and insulator, making the diode a one-way street for current. The transistor is essentially two diodes place back to back and has the ability to act as a switch.

For the first exercise of the day, we were tasked with created a circuit that displayed the voltage amplifying abilities of the transistor. When a signal was applied to the input of the circuit, that signal would be significantly larger in magnitude at the output.

With the oscilloscope connected to the input and output of our circuit, we were able to verify that the signal had indeed be amplified.

We also noticed that the output signal would get cutoff if we applied too much voltage on the input signal. We learned that this was due to the transistor being driven into saturation from the large amounts of voltage being applied to the base.

 The transistor is a three lead component. Each lead corresponds to parts of the transistor known as the emitter, collector and base.

For the final portion of the day, we were introduced to the op-amp and the concept of integrated circuitry.  An integrated circuit is an entire circuit that is boxed as an individual component. The op-amp is an integrated circuit that can act as a voltage comparator. By using the properties of feedback, the op-amp can be used as a signal amplifier much like the circuit that was previously built.

The amplifier circuit was built and tested with the output from a device that is capable of outputting sound to a speaker jack such as a phone.  The low voltage signal was passed through the circuit and sent to a speaker, where the low voltage signal had gained enough voltage to be loud enough for everyone the hear.