In this tutorial, I will be sharing my prototype version of a LED bench tester using the Arduino Nano. The configuration will perform a continuity test and bulb burn-in for 16 standard, 2-node LED bulbs.
With this tutorial being the first on Indestructibles and having a white-belt in hobby electronics, my goals for this project are:
- Break the ice on Instructables.
- Create a project that uses common parts and is budget minded.
- Inspire one person.
Step 1: Gathering the Components
Components used for prototyping:
- 1 - Arduino Nano
- 8 - Tall female headers
- 17 - 220-ohm resistors
- 1 - 10k-ohm resistor
- 1 - Push button
- 1 - standard red LED
- 2 - Breadboards
- 16 - Various standard LEDs
- Jumper wires
- (Optional) 9V battery connector with leads only
- (Optional) 9V battery
Step 2: Setting Up the Breadboards
1. Implement Nano. Begin by pressing the Nano into the breadboard end with the mini USB connector facing away from the breadboard.
2. Implement header blocks. Insert a tall header block several rows away from the Nano. The placement will parallel recessed strip located in the center of the breadboard. Place a second tall header block in parallel to the first one, on the opposite side of the recessed strip. The idea is to not have continuity between the two header blocks Repeat the preceding steps with the remaining header blocks, leaving two or the rows in between. The end-result will be 4 groups of parallel blocks.
3. Implement resistors. If your resistors from the tape, gently bend the leads in a arc shape. No need to cut and waste. Starting with block group closest to the Nano, place one end of the 220-ohm resistor on the correct header pin and opposite end to the negative bus strip. Repeat preceding instructions for the remainder of the resistors. Use the header block group/pin ID diagram for proper pin identification. A total of 16 220-ohm resistors will be used.
4. Implement switch/pull-down resistor. On the second breadboard, place the push button switch in the middle, straddling the recessed strip in the center. Place one end of the 10k resistor on a switch lead and the opposite end to the negative bus strip.
5. Implement cycle LED. On the breadboard with the switch, place the red LED anywhere in the terminal strip area as long as LED leads are on different terminal strips.Place the last 220-ohm resistor with on end to the LED cathode and the opposite end on the negative bus strip.
6. Implement the wiring. To wire the circuits, use the connection guide below along with header block group/pin ID diagram.
- Nano pin D2 to block 1, pin 1
- Nano pin D3 to block 1, pin 3
- Nano pin D4 to block 1, pin 5
- Nano pin D5 to block 1, pin 7
- Nano pin D6 to block 2, pin 1
- Nano pin D7 to block 2, pin 3
- Nano pin D8 to block 2, pin 5
- Nano pin D9 to block 2, pin 7
- Nano pin D10 to block 3, pin 1
- Nano pin D11 to block 3, pin 3
- Nano pin D12 to block 3, pin 5
- Nano pin D13 to block 3, pin 7
- Nano pin A0 to block 4, pin 1
- Nano pin A1 to block 4, pin 3
- Nano pin A2 to block 4, pin 5
- Nano pin A3 to block 4, pin 7
- Nano pin A4 to the opposite lead of the switch with the 10k resistor
- Nano pin A5 to the to the anode of the red LED
- Nano 5V pin to on of the open leads on the push button switch
- Nano GND pin to negative bus strip on the breadboard with the Nano
- Negative bus on breadboard (Nano) to the negative bus to negative bus on breadboard (switch).
Step 3: Getting the Code
The sketch used for this build is very simple and straight forward. The burn-in cycle executes for about 1 minute and 20 seconds over 3 cycles. The first cycle is a 20-seconds of full burn. The second cycle is a 40-second blink cycle and third cycle is another 20-second full burn. The sketch should provide a verbose burn-in and hopefully, a good filter of defective LEDs. The sketch uses the push button to start the cycle. Once a cycle has started, the red LED will be lit and no new cycles can be started. Once red LED light is out, a new cycle can be executed. Please customize the sketch to fit your needs. The default delay is set at 200 milliseconds but you can also control duration by changing the for loop iterations.
Step 4: Prototype Execution
1. Implement the code. Power up the Nano and proceed with uploading the sketch. Once the upload is complete the cycle indicator will be off.
2. Add the test LEDs. Place a test LED in each of the header blocks using the proper pin locations. It is important that the anode lead is placed in header pin opposite of the resistor. You can use the header block group/pin diagram for reference. Don't forget that every other pin is dead.
3. Execute the sketch. Press the push button and see how circuit reacts. The red cycle LED should be lit along with all 16 LEDs.
4. Repeat the cycle for one more iteration.
5. (Optional) Implement the 9V. If battery power is desired, use the connection guide below to wire the circuit:
- 9V red to Nano VIN pin.
- 9V black to Nano GND pin.
5.If the circuit, sketch and LEDs are operating as expected, congratulations and well done.
Step 5: Implementation (Coming Soon)
My goal for this project is incorporate the circuit onto a PCB housed in some type of a enclosure. Please check back for project progress and post any comments in the feedback section below.