Print PDF
Favorite
Email
Step 12Compare the outcome to the original specification.
So here's how I did compared to my original specification:
"The light shall not affect the 'stock' look of the bike." Check. It looks like a stock reflector unless you take a peek around the seat.
"The light shall operate only when it's dark enough to be effective." Check. It turns on only after dusk but not in the daytime.
"The light shall operate automatically when the bike is in use and for around 30-60 seconds afterward." Check. It stays bright for about 30 seconds afterward, dim for 90 seconds or so, then slowly fades to black over the course of several minutes.
"The light shall blink to enhance visibility at night." Nope. I just couldn't get this to work. In the end, though, it looks more "stock" to have it not blink, somewhat like an old incandescent battery-powered tail light.
"The battery on the light shall last 'indefinitely' when not in use." Check. I measured the current draw after the lights had been off for over a day and it came out to 1.1 microamps. Given a 540 milliamp-hour battery, that's 480,000 hours or about 54 years.
"The light shall efficiently utilize the battery's power when in use." Check. Although I didn't do a thorough test of conditions while riding, I did several measurements. When the vibration switch is activated, the circuit draws 21 mA. Once it disconnects, the circuit draws 14 mA and begins dropping -- to 11 mA after 30 seconds, and 3.7 mA after 90 seconds. Assuming it stays around 14 mA, the 540 mAH battery will provide light for about 38 hours -- or 38 hours of continuous riding.
Further, I did a test to see how the current decreases over time. If I understand it correctly, it will continue to approach the minimum of around 1.1 microamps. I measured the current after the last pulse of the vibration switch up to around 15 minutes when it was down to 200 microamps. I'll assume it takes 3 hours to drop to 1.1 microamps. If I approximate that between each time measurement that the current drops linearly, I can estimate the total energy consumed to be the average current between two points times the time between those points. Doing that, I determined that the total energy consumed the last time the vibration sensor fires is about 0.7 millamp-hours, so for a 540 mAH battery, that's about 770 times.
"The electronics of the light shall be reasonably weatherproof -- at least enough that road spray will not affect operation." Check. The film canister protects the battery and the sauce container protects the main circuit.
All told I'm quite satisfied. My girlfriend is impressed and happy about it as well.
"The light shall not affect the 'stock' look of the bike." Check. It looks like a stock reflector unless you take a peek around the seat.
"The light shall operate only when it's dark enough to be effective." Check. It turns on only after dusk but not in the daytime.
"The light shall operate automatically when the bike is in use and for around 30-60 seconds afterward." Check. It stays bright for about 30 seconds afterward, dim for 90 seconds or so, then slowly fades to black over the course of several minutes.
"The light shall blink to enhance visibility at night." Nope. I just couldn't get this to work. In the end, though, it looks more "stock" to have it not blink, somewhat like an old incandescent battery-powered tail light.
"The battery on the light shall last 'indefinitely' when not in use." Check. I measured the current draw after the lights had been off for over a day and it came out to 1.1 microamps. Given a 540 milliamp-hour battery, that's 480,000 hours or about 54 years.
"The light shall efficiently utilize the battery's power when in use." Check. Although I didn't do a thorough test of conditions while riding, I did several measurements. When the vibration switch is activated, the circuit draws 21 mA. Once it disconnects, the circuit draws 14 mA and begins dropping -- to 11 mA after 30 seconds, and 3.7 mA after 90 seconds. Assuming it stays around 14 mA, the 540 mAH battery will provide light for about 38 hours -- or 38 hours of continuous riding.
Further, I did a test to see how the current decreases over time. If I understand it correctly, it will continue to approach the minimum of around 1.1 microamps. I measured the current after the last pulse of the vibration switch up to around 15 minutes when it was down to 200 microamps. I'll assume it takes 3 hours to drop to 1.1 microamps. If I approximate that between each time measurement that the current drops linearly, I can estimate the total energy consumed to be the average current between two points times the time between those points. Doing that, I determined that the total energy consumed the last time the vibration sensor fires is about 0.7 millamp-hours, so for a 540 mAH battery, that's about 770 times.
"The electronics of the light shall be reasonably weatherproof -- at least enough that road spray will not affect operation." Check. The film canister protects the battery and the sauce container protects the main circuit.
All told I'm quite satisfied. My girlfriend is impressed and happy about it as well.
| « Previous Step | Download PDFView All Steps | Next Step » |
 |
Add Comment
|
