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November 1, 2018
November 1, 2018
One of my hobbies includes riding motorcycles. I picked up a Yamaha Bolt in 2018 and I've been making some changes to it, to better fit my style. I didn't like the look of the stock turn signals and I also had some ideas for improvements to the way the signal functioned. This included making them a bit brighter and serving as a running light when the signal is not in use.
One of my hobbies includes riding motorcycles. I picked up a Yamaha Bolt in 2018 and I've been making some changes to it, to better fit my style. I didn't like the look of the stock turn signals and I also had some ideas for improvements to the way the signal functioned. This included making them a bit brighter and serving as a running light when the signal is not in use.
Initial Design
Initial Design
My goal for this design was to improve visibility and overall function. With this in mind I knew that I would need some powerful LED's to make it all happen. I also knew that I would like to do something a bit different with the actual function of the lights. When they aren't being used, they are completely off. In order to improve visibility, I wanted to put red running lights on the PCB along with a cluster of amber LED turn signals.
In the first revision of the board, I wanted to have a turn signal that lit three strips of amber LEDs in succession, signaling the direction I was turning. I also wanted the red LEDs to fade on when the bike started up, shut off when the turn signal was engaged, then fade back on once the turn signal was disengaged. The schematic here shows how I initially attempted this using a 555 timer and some buffers. This sort of worked, but it wasn't what I was hoping for. You can read more about the details of this circuit here, but the majority of it was rendered obsolete with the second revision of this board. After building this circuit I found several problems with it. Things weren't working as expected, it was overly complicated, and the amber LED's firing in succession wasn't even noticeable on a small scale under the turn signal lens. It just looked like a single light getting progressively brighter. This prompted me to go back to the drawing board and find a solution. I did like the fading red LEDs, so those would be kept, but the amber LED strips would have to go. I would also need to find brighter LEDs for this project. The SMD LEDs I originally selected were nowhere near bright enough for this application.
The first revision schematic - most of it was scrapped
The first revision circuit board shows the SMD LEDs selected initially. Although they appear bright here, they were actually very dim in sunlight and the amber LEDs were even worse. I typically don't have a PCB like this manufactured unless I know it's going to work. This process is somewhat expensive and it takes a couple weeks at best to get a set of boards made. This is just a case were I needed to see it on a PCB before I could really understand what needed to be improved. In the future I plan on refining my board making process to cut cost and production time. I'll be etching my own PCBs in-house.
The first revision PCB displaying the red running lights
Revising the Design
Revising the Design
The first revision of the board was mostly a failure, but it wouldn't stop me from creating a circuit that functioned the way I imagined. For the second revision of this board I took my design to Eagle. I typically work inside of Fritzing, which is a great open-source circuit design software, but I thought I would try something different this time around.
I typically prefer to hand draw my schematics, but Eagle allows you to create a nice looking schematic while designing the PCB. Here you can see the second revision schematic. It's much cleaner than the first revision and also cuts down on component count while still maintaining the overall functionality of the circuit. For a step by step breakdown of this circuit, check here.
This circuit did exactly what was intended. The red LED running lights fade on as expected and the amber LED turn signal works perfectly. The functionality of the circuit was tested on a breadboard before having the PCB manufactured. I also selected much better LEDs from Digikey that were bright enough to be seen well during the day.
Second revision schematic - this one functioned perfectly
Quite a bit of testing was done on this circuit before I was confident that a proper PCB could be produced. Notice in the photo below the two breadboards being used for testing and all the spare components lying around. I wanted to make sure that I selected the proper components for this project. It was very important that nothing failed, especially for something as critical as the turn signals on a motorcycle. The LED that was selected for this job turned out to be much brighter than I expected, and a cluster of them was blindingly bright up close. This worked perfect for the turn signal because it could be seen on a sunny day.
Testing the circuit before having the PCBs manufactured
A single amber colored LED used for the turn signal
Board Layout and Assembly
Board Layout and Assembly
This PCB was created inside Eagle, as stated earlier. The PCB design process was simplified because Eagle's schematic is linked to the PCB. All connections were shown based on the connections in the schematic. This meant that the only thing I had to do was physically route the traces, making the process quicker than it typically would be. The image below displays the top and bottom traces of the PCB, the red and blue tracks. This is how the gerber files are created for manufacturing.
An image inside of EAGLE showing the top and bottom traces of the turn signal PCB
Assembling this board was a simple process. There were no components that were too small to handle and there was plenty of space to work in because the component count was small. As you can see in the photo, the LEDs and their resistors are very large for surface mount devices, which made soldering a breeze. I used a product by MG Chemicals called "silicone modified conformal coating" to make this PCB water resistant. A couple coats was all that it takes and the product is easily applied with a brush. Once the coating is dry it's almost invisible, leaving only a slight change in hue.
A close up image of the assembled PCB
Testing
Testing
There was no good way to test this board on the motorcycle. I needed to cut my signal wires and solder these in, which is not ideal for testing. In order to get around this I created a turn signal generator circuit. I could hook up my PCB to this generator and test it without hacking up my wiring harness. The generator worked by using a 555 timer to simulate the signal that would be present in the motorcycle turn signal circuitry. In the absence of this signal, the red LED running lights would fade on and stay on until the signal was engaged. Once the signal engaged, the red LED running light would be shut off and held off while the turn signal flashed the amber LED signal lights. When the signal is shut off, the red LED running lights would fade back on.
The PCB attached to the signal generator
An image displaying a cluster of amber LED signal lights
3D Printing
3D Printing
In my opinion, the rear turn signals on my motorcycle stuck out too far, making them look like bug eyes. As long as I was building an entire circuit for this, I decided to go ahead and fix the signal housing. To do this, I shortened the stems to bring the housing closer to the frame of the motorcycle. I also gave them a warplane style nose for a little bit more edge. I designed the cover to simply click into place, rather than using a screw as shown in the below renders. The only problem I still had to solve was creating a clear lens for the housing.
Side-view of the turn signal housing created with Blender
After quite a bit of work modeling the parts for this build I finally got them printed. The components fit into the housing perfectly and everything worked as intended. A prototype was assembled and tested. In the following picture you'll notice the amber colored light coming from the housing. I printed a slightly transparent orange lens for the project so I could get an idea of what the finished product might look like. It had the side-effect of dimming the amount of light emitted from the PCB significantly. Honestly, I wasn't as pleased with the design as I had hoped to be. I felt that it didn't mesh well with the overall look of the bike and I would need to go back to the drawing board on the design.
The turn signal PCB in the housing under an orange lens
Ultimately, this circuit would not be utilized on my motorcycle. I actually found very attractive looking bullet style signals that were used instead. I would however like to convert the lamp in the bullet light to LED at some point and I may try to shrink this circuit down to fit, though it will be a challenge. I will update this page to reflect any changes I decide to make to the turn signals.
Ultimately, this circuit would not be utilized on my motorcycle. I actually found very attractive looking bullet style signals that were used instead. I would however like to convert the lamp in the bullet light to LED at some point and I may try to shrink this circuit down to fit, though it will be a challenge. I will update this page to reflect any changes I decide to make to the turn signals.
UPDATE: The signal has been shrunk! I've got some fine tuning to do, but I'll document my work when it's done. I'll create a new page just for the miniaturized turn signal because the circuit has changed a bit to accommodate the small form factor. It's a triple stacked board to fit the tiny housing! Look for "Motorcycle Turn Signal: Revision 2" to be added to the menu.
UPDATE: The signal has been shrunk! I've got some fine tuning to do, but I'll document my work when it's done. I'll create a new page just for the miniaturized turn signal because the circuit has changed a bit to accommodate the small form factor. It's a triple stacked board to fit the tiny housing! Look for "Motorcycle Turn Signal: Revision 2" to be added to the menu.
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