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2.24.9 The entire apparent surface of direction indicator lamps must be visible 15° up and 5° down. Minimum horizontal visibility requirements (of the right direction indicator lamps) are shown in the following diagram.
Direction indicators for the front of the vehicle:
Category 1:For use at a distance not less than 40 mm from the dipped-beam headlamp and/or the front fog lamp;
Category 1a:For use at a distance greater than 20 mm but less than 40 mm from the dipped-beam headlamp and/or the front fog lamp;
Category 1b: For use at a distance less than or equal to 20 mm from the dipped-beam headlamp and/or the front fog lamp.
Categories 2a and 2b: Direction indicators for the rear of the vehicle.
Category 2a:Rear direction indicator lamps with steady luminous intensity.
Category 2b:Rear direction indicator lamps with variable luminous intensity.
Categories 5 and 6: Supplementary side direction indicators for use on a vehicle also equipped with categories 1, 1a or 1b and 2a or 2b direction indicators
https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2015/R006r6e.pdf
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Lights shall be powered by a 12 volt power source
Light shall be centered on a flat surface with a matte white finish of 11” x 8.5”.
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Reference standard light boards shall be set aside of car to compare during inspections.
Parts:
Red Lights
Amber Lights
White Lights
Optimizing PCB thermal performance:
https://www.cree.com/led-components/media/documents/XLamp_PCB_Thermal.pdf
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Design
Drivers:
https://www.digikey.ca/product-detail/en/texas-instruments/TPS61165DBVR/296-27597-1-ND/2340765
Prototype Rev 1:
3 LEDs in series with no additional parts. Lights were sufficiently bright and stable, but became very hot (around 80 C) very quickly.
Prototype Rev 2:
6 LEDs in series driven by a boost converter. PWM signal provided by 555 timer. Potentiometer included in 555 timer circuit to allow experimentation with duty cycles. LEDs and current sense resistors are kept on a separate board to account for the physical constraints of the car.
List of issues:
- Lack of decoupling capacitors
- Incorrect capacitor value for 555 timer (which set the incorrect frequency for the CTRL pin on the driver).
- Pins configured incorrectly
- Lack of ground pour for stability
- Inductor was not placed close enough to the potentiometer (no boost was measured).
Further Testing for Rev 2:
- Measure current at the connectors on startup to determine whether additional capacitors are required at the connectors.
- Measure power dissipation and efficiency of the driver.
Next Steps for Rev 3:
- Fix the obvious mistakes
- Determine whether heat dissipation for the LEDs is done through electrical ground (move current sense resistors to the main board if it is not).
- Calculate expected power dissipation of the driver, and determine expected temperature from it.
- Determine what voltage is required to replace the potentiometer and set the duty cycle of the PWM signal.
General Testing for Lights:
- Measure brightness of the LEDs.
- Ensure that the driver is boosting the voltage properly.
- Ensure that temperature is within safe limits (<100 C).
- Measure the stability of the LEDs by using a varying voltage.
- Measure the current and voltage on startup at the connectors.