On Show

Christopher McQuillan

BSc [Hons] Creative Media Technologies

I have completed the honours BSc in Creative Media Technologies at IADT. My interests are problem solving and being creative with my hands. I like to work with tools and have something to show for it at the end. As a result of doing this course I gained an interest in working with electronic circuits and acquiring new skills in the electrical industry. This has shaped my desire to pursue a career in this area.

The temperature sensor is a useful feature as it reads the overall temperature of the environment within the housing. This is important due to the fact that power amplifiers can generate a great deal of heat that can in turn damage the circuit from melting. Average operational temperature is 60 degrees Celsius and so the sensor was tested to high temperatures. On the higher end of the temperature scale when readings reach around 70 degrees and upwards, circuit damage is most likely. In order to combat this an Arduino microcontroller reads the temperature at all times and when the temperature exceeds the set threshold it sends a signal that activates the cooling fan. This allows the circuit to run at safe temperatures.

The circuit was designed and initially tested and simulated using the industry standard circuit simulator LTspice. Using LTspice, the circuit was developed into what would later on become the printed circuit board (PCB). This board was built in Eagle. Each component was chosen based on compatibility with the other components and also availability. From there it was tested for errors and saved before being converted to a PCB. This PCB layout was created with the aim of using the space efficiently and meeting the specifications of the manufacturers requirements. When the PCB was complete it too was checked for errors and then generated into a digital "Gerber" file that was then sent to the manufacturer in Shenzen, China, for fabrication.

After receiving the PCB I began the next stage of the built, assembling and soldering it togeher. Firstly each component was laid out on a large sheet with a layout of the board. This allowed for no confusion or mistakes in the soldering as it was clear where they were to go. On completing the circuit the input and output terminal blocks were soldered in place and the input voltage pins were connected to the power supply. The power supply was set to plus and minus 12 volts in order to test the circuit. This voltage was decided upon due to certain components voltage ratings.

Project Description

The project is a power amplifier and a modern take on a classic. It brings together digital elements of a temperature sensor and microcontroller, and the analogue elements of an amplifier with the aim of delivering pristine sound quality.

Thesis Title: Power Amplifier

A power amp or an audio power amp is one of the main parts of an amplification system. It is
placed between the preamp and the speakers. A power amplifier is a piece of equipment that
that amplifies low-power electronic audio signals such as electric guitars, microphones etc.
that are inputs to the preamp. The audio signals are boosted to a level of power which is
measured in watts that is high enough to drive headphones and loudspeakers.
The first power amplifier was built in 1912 by Lee De Forest (Audio power amplifier 2020).
He used an electrical component called the triode vacuum tube or valve that he too invented.
This device had three terminals with a control grid that could modulate the flow of electrons.
This design was used to make the first AM radio.
Today these valve amps are not as widespread and have been replaced with cheaper more
readily available amps made with electronic components. However, many musicians and
audio engineers prefer tube-based amplifiers as they tend to have a warmer sound.
The aim of this project was to build a power amplifier by hand with the use of components,
soldering and software to simulate the circuits, using a collection of skills I have acquired over
the last four years at IADT.