"This instructable was created in fulfillment of the project requirement of the Makecourse at the University of South Florida (www.makecourse.com)"

The Led Test Fixture is design to measure the light output of any Led with a specific currents (10mA, 20mA, 30mA, and 40mA) from -90 degree to +90 degree.

## Step 1:

3D Printed Led Post

Design the Led post using a 3D cad program (Autodesk Inventor 2017) and print it with 100% infill. Depending on the size of your servo your post can very in size.

## Step 2: Arduino Sketch

The following code is deign to control a servo, rotating it 45 degree from 0 degree to 180 degree with a 15 second delay in between.

#include

Servo myservo; // create servo object to control a servo

int pos = 0; // variable to store the servo position

int Start=15000; // delay time at the begining

int Middle=15000; // delay time in the middle

int End=15000; // delay time at the end

void setup() {

myservo.attach(9); // attaches the servo on pin 9 to the servo object

}

void loop() {

myservo.write(pos);

delay(Start); // time before starting

for (pos = 0; pos < 45; pos ++) { // goes from 0 degrees to 45 degrees

myservo.write(pos); // tell servo to go to position in variable 'pos'

}

delay(Middle);

for (pos = 45; pos < 90; pos ++) { // goes from 45 degrees to 90 degrees

myservo.write(pos); // tell servo to go to position in variable 'pos'

}

delay(Middle);

for (pos = 90; pos < 135; pos ++) { // goes from 90 degrees to 135 degrees

myservo.write(pos); // tell servo to go to position in variable 'pos'

}

delay(Middle);

for (pos = 135; pos < 180; pos ++) { // goes from 135 degrees to 180 degrees

myservo.write(pos); // tell servo to go to position in variable 'pos'

}

delay(Middle);

for (pos = 180; pos > 0; pos --) { // goes from 180 degrees to 0 degrees

myservo.write(pos); // tell servo to go to position in variable 'pos'

}

delay(End);

}

## Step 3: Current Regulator Box

• Image 1 show the schematic of the adjustable current regulator. Depending on how many different value you like to test. That's how many trim pot you're going to need.
• Image 2 is an example for 4 current option using a 200 ohm trim pot.
• Image 3 and 4 show how to set up a rotary switch to select the different out put and the rocker switch is an on/off switch to save energy.

## Step 4: Puting It Together

• Paint a board that is 4'x2' black (image 1)
• Twist 3 (22 awg wires) about 6' long (image 2)
• Install your servo on top of the box (7.5"x4.5"x2") and screw the bottom to the board. Make sure to drill a hole to feed the twisted wires from the servo and run it under the board (image 3, 4, 5)
• Place your photometer and the current regulator box on the other end of the black board (image 6)
• Lastly wire everything together and plug your system to the laptop (image 7 and 8)