Failure Report – Nicholas Weddington

This week I did more testing as some of my parts arrived to see what things would work and what would not. Unfortunately, as expected, some things did not work out as planned. I was torn between purchasing a long skinny tube charger or a flat charger. I tested out various placements on the waistband and the hip, but the positioning was not comfortable, so I decided to go with the flat square charger. I figured that I could make a pocket on the inner lining of the pants and it would look like a cardholder, but when the charger arrived, it was much larger than I predicted. Now I am looking for a smaller but safe alternative. I considered using a lithium-ion battery cell and connecting it to a USB-A Receptacle, but I need to do more research on power regulation to emphasize safety.

I tested the LEDs with the fiber optic cable and the app. The app connected very easy and fast with a great Bluetooth connection. To temporarily power the lights during testing, I used my portable charger rated at 1000mA and after 35 minutes I noticed that the lights were getting very warm. The strip got warm sitting under the pillow (as I was trying to block out excess light), so I could only imagine how fast they will get hot compressed to someone’s waistband. This raised a concern to me because if the user wears the pants for a long time, they could possibly end up getting burned if the LED strips get too hot. The problem was that too much current was being drawn from by the LEDs from the battery. If I decrease the current of the battery then the battery won’t last as long. If I add resistors to decrease the amount of voltage running through LED strips, the light intensity would diminish and high intensity is required for the light to be seen at the end of the fiber optic cable. If I shorten the LED strips to about 1/3 the original length (the size of an average men’s waist), it will draw less current so the lights will not heat up as fast.

LED Light Strip

When testing the light intensity while the optics are connected directly, I noticed the highest intensity came from them being placed directly in the center of the LED. With a low intensity, I figured in order to have light visible through the cables majority of the time, I would need to include more cables at mediocre intensity. The extra cables would need to come from the center of the LED so they can maximize intensity. I tried piercing the silicone coat over the LED strips but it would not stay and stuck out perpendicular. I cut the silicon and placed the cable inside and achieved the desired result. I figure that I can include 8-12 cables at each LED and seal the cut with liquid silicon. I still ran into the issue of having to place them at a right angle so I tried filing down the end of the optic so that they can be flushed to the LEDs but still lay sideways. This was not as effective as I predicted because the light at the end had a lower intensity than before. I blame this decrease on the opaque new surface of the cable, so I will need to file down and polish each end before attaching it to the LED. I have worked on the design I for how exactly to place the cables in the jeans. I will start threading them through once the fiber optic cables arrive on Wednesday.

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