Test

LED Angle vs Color Sensor Signal

The second experiment is designed to see how much interference will be caused as the angle between LED and color sensor changes. Different from the first experiment, V_i, the voltage before amplified, is mesured since amplified output, V_o, easily reaches to the maximum.

Setup and Results

1. A white LED is used again in this experiment with the same reason above for the first experiment.

• LED: 18950 mcd, Digikey part number: C503B-WAN-CABBB151-ND

2. The experiment was performed under the two conditions; with the ambient light and without the ambient light.

3. In this experiment, the distance between LED and color sensor is kept constant, 1 inch.

4. Angle between LED and color sensor is increased by 15º each time from 0º to 90º.

When the angle is 0º, the LED and the color sensor is placed at the same horizontal plane. The LED is facing toward the color sensor(this means that the LED is parallel to the horizontal plane with its head facing the color sensor, which is placed on the same horizontal plane), and the color sensor is facing upward. We increased the angle by 15º each time, and increasing amounts of light from the LED shines onto the color sensor. When the angle is 90º, the LED is right above the color sensor, facing the color sensor directly. This means that the LED and the color sensor are now on the same vertical line, and the LED is facing downward.

5. The voltage before amplified, V_i as shown in the circuit diagram above, of each photodiode is measured.

• The reason to measure the volatage before amplified is that the output becomes too large after amplified.

With the Ambient Light

• Unit: Volt, V

Angle vs Voltage Before Amplified

Angle	R	G	B
0º	0.437	0.425	0.404
15º	0.475	0.470	0.451
30º	0.490	0.491	0.501
45º	0.505	0.506	0.520
60º	0.484	0.468	0.484
75º	0.457	0.453	0.440
90º	0.439	0.430	0.408

Without the Ambient Light

• Unit: Volt, V

Angle vs Voltage Before Amplified

Angle	R	G	B
0º	0.446	0.436	0.416
15º	0.454	0.491	0.461
30º	0.493	0.505	0.480
45º	0.512	0.521	0.520
60º	0.498	0.486	0.491
75º	0.498	0.492	0.487
90º	0.485	0.479	0.515