Olfaction Satisfaction Week #10 April 5, 2006 Senior Design Team 8

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1 Olfaction Satisfaction Week #10 April 5, 2006 Senior Design Team 8 Work Completed The first task for Emily this week was to finish debugging the circuit. The sound chip problem was finally figured out. Since the chips were drawing too much current, a new setup would have to be determined. (see Figure 1). The ping sound chip did not require this change because it did not draw too much current. The lion, dinosaur, and lion are now each connected to two of the solenoids. The ping will now sound whenever a new scent is chosen (cycle through indicator LEDs). Figure 1: Sound Circuit Problems with the solenoid circuit were collectively dealt with in a team effort. Pearl and Emily it was found that the driver did not actually need a 22 uf capacitor connected to ground on the sixth pin (see Figure 2). Also, it was discovered that the previous chip was burnt out and so a new chip and a new PDIP adaptor were needed (see Chris s Report). Once these changes were made the solenoid circuit worked as desired. Each of the PIC pins was tested with the solenoid setup, as well as the actual fragrance spray mechanism 1

2 within the device. Figure 2: Solenoid Circuit We also discovered that the voltage regulator became very hot while the circuit was on and running. To solve this problem, a second voltage regulator was added to divide the current. This voltage regulator will power the LED pattern circuit since it draws the most current out of all the subsystems. A problem was also encountered with the user switches. The problem was fixed by adding a pull-up resistor (see Figure 3). In addition, the 22 pf capacitors originally attached to the oscillator were incorrect and removed. Figure 3: Main Circuit 2

3 Once all these changes were made, the circuit actually worked as intended (see Figure 5). Because the circuit now worked, Emily s second task of the week could be completed: the PCB layout. All of the above changes were updated on the PCBExpress schematics and alterations were made accordingly to the PCB layout. After some considerable rewiring, editing, and general cleaning up, the PCB was ordered. Along with the PCB, all the necessary electrical components including resistors, capacitors, dip socket, and battery were also ordered. Figure 5: Working Circuit Setup The assigned structural fabrication tasks that were assigned to Pearl were put on hold until all circuitry problems are solved. Due to the importance of sending out the PCB order as soon as possible, she called to help in solving and fixing the circuitry components before continuing with structure fabrication. As mentioned earlier, it was discovered that solenoid driver chip was fried, but was dealt with (figure 5 above). Following this, Pearl was able to resume structural fabrication. In order to install the jacks for the switches and the key-lock switch, the milling method was required in order for these components to fit on the ¾ thick PVC sheets (figure 6). 3

4 Figure 6: Jacks and key-lock Installations After the jack and switch installation, four speakers are install on the front panel. A design was made with a drill on each speaker pocket, allowing the sounds to exit into the environment (Figure 7). Figure 7: Speaker Installations Chris s attempts at removing the surface mount solenoid driver from the PDIP adaptor resulted in damaging the adaptor (Figure 8). Fortunately, Senior Design Team 6 had an extra adaptor which they loaned to us for testing (Figure 9). Installing a new chip into the adaptor and rewiring the circuit allowed the team to successfully demonstrate a working solenoid circuit. Chris helped Emily and Pearl to tweak the circuit design of the sound chips so that they would fully function along side the PIC. Changes took the form of directly powering the 4

5 chips from the battery while still maintaining control of their activation by the PIC. The final working circuit setup is shown in Figure 1. Once the PCB was ordered, Chris soldered and insulated all the connections to the solenoids (Figure 10). Insulation ensures electrical insulation to protect the user from accidental harm. Similar treatment was given to the Indicator Lights. Furthermore, he braided the wires for the LED s, Indicator Lights, and Fans. Figure 11 shows the finished product. Figure 8: PIC PC Circuit 5

6 Figure 9: Protoboard Setup Figure 10: Protoboard Setup 6

7 Figure 11: PIC PC Circuit Future Work Now that the PCB is ordered and all the components for the device have been prepared for final assembly, it is just a matter of putting the device together once the PCB and other components come in. Everyone on the team is clear regarding their final tasks regarding the final assembly. Following this, a team effort will be made to prepare a Poster for the project, a final report, a user s manual, and a power point presentation. Table 1 shows the timeline for the final assembly. 7

8 Table 1: Timeline for the Final Assembly Project Review For a while it seemed that we may never be able to finish the project on time, however with the successful demonstration of our circuit s validity and the successful debugging of the PIC, we are now confident that the final assembly of the device can be completed within the allotted time. Though we are in a tight schedule due to not ordering the PCB three weeks before the deadline but we are optimistic to have everything finished by the deadline (April 7). There are still needed minor adjustments on the interior fabrication but it would be completed by the beginning of next week. Once the PCB board arrives, we ll be able to solder all the components onto the board and put everything into the structure. 8

9 Hours Worked Emily: 30 hours Pearl: 32 hours Chris: 22 hours Total: 84 hours 9