Wired Optical Mouse Dissection
For the “Take it Apart and Figure It Out” Project, Team Arsenic was given a wired optical mouse. The mouse brand was Onn, produced by Blue Trace Technology and sold by Wal-Mart. During the in-class part, we obtained a basic understanding of the workings of the mouse, but, to completely understand the operation of the mouse, we had to research the various parts individually since no blueprint for the mouse exists. After understanding the individual parts of the mouse, we figured out how they work together to scroll the cursor, move across web pages, and select options through the buttons of the mouse. In order for the mouse to be powered, it must be plugged into a power source, as this is a wired mouse. In this case, the mouse receives power through the universal serial bus (USB) port. The cord entering the mouse has four wires; two are for power, and two are for data. The grey is the hot wire while the blue is the ground. For data transfer, green provides the incoming data stream while white provides the outgoing data stream. When the power enters, it immediately goes to the microchip.
The microchip processes all operations of the mouse. It is responsible for all the responses the mouse makes to movements by the operator. The microchip also houses a semi-conductor, the importance of which will be explained later. Once power reaches the microchip, it distributes it to different portions of the mouse including two contact switches, a scrolling wheel, the switch on the wheel, and a light emitting diode (LED).
Before reaching any of these portions of the mouse, however, the current must flow through a series of mica capacitors, electrolytic capacitors, and resistors. In this mouse, five capacitors (two mica, three electrolytic) and one resistor control the current to the LED.
The mouse contains two contact switches (push button switches) at the front for the left and right buttons. The...