Temperature
The LEDs used for the lights can get very hot very quickly. It is important that the temperature of the lights stays within limits that will not interfere with the functionality of any nearby circuits, and will not pose a safety hazard.
The graphs below represent the temperature of the light board over time. All trials were performed with 12V supply. Duty cycle was set to 100%.
Red Lights: back
Temperature appears to be unstable throughout the trial, this is because the temperature probe came off of the board. Temperature at the end is somewhat more stable. Temperature stabilized to around 66 degrees.
The power supply drew 0.43 A of current (5.16 W).
Red Lights: front
Temperature stabilized to around 68 degrees.
The power supply drew 0.43 A of current (5.16 W).
White lights: back
Temperature stabilized to 79 degrees.
The power supply drew 0.59 A of current (7.08 W).
White lights: front
Temperature stabilized to about 90 degrees.
The power supply drew 0.59 A of current (7.08 W).
Voltage Boost
Since a boost converter is used in the driver board, a boost in output voltage is expected.
Voltage boost changes depending on PWM duty cycle (which can be adjusted with the potentiometer).
Here are the results for voltage boost and supply current as a function of duty cycle. The power supply was set to 12 V.
Duty Cycle (%) | Voltage Boost (V) | Supply Current (mA) |
|---|---|---|
<1 | -0.503 | 170 |
15.14 | -0.494 | 170 |
44.05 | -0.429 | 175 |
72.24 | 0.077 | 295 |
88.17 | 0.273 | 360 (recommended current is 350 mA) |
Very high (>99) | 0.398 | 410 |
Burnt out LED
When a single LED was removed, the remaining LEDs were fully illuminated at approximately 3V. Constant current mode was activated on the power supply. Supplied current was 250mA.
Brightness
Brightness was measured in a dark room with a photometer. The LEDs were driven directly at 12V, without the driver (they burnt out in an accident, guess who did it)
This website was used to convert from lux to candela:
https://www.rapidtables.com/calc/light/lux-to-candela-calculator.html
Amber reference lights:
60 lux from 1 foot = 5.6 cd
the ruler that was used was slightly reflective.
Red lights:
12 V * 0.21 A = 2.52 W
850 lux from 1 foot = 78.9 cd
This circuit included the zener diodes used for protection.
the ruler that was used was slightly reflective.
White lights: