One of the key features of the car is the lights. This will consist of headlights, brake lights and indicators. The thought is that the headlights can be controlled by the users and the indicators and brake lights will trigger automatically based on the motion of the car. Either way they will all ultimately be controlled by the Intel Edison and it's likely I'll use the Arduino breakout and Grove shield for its pluggable headers.
Headlights
The other year I had some LED downlights that failed on me. Curious to know what they had inside I cracked one open to see. After removing the glass and a load of potting compound I broke out a simple board with some LEDs on one side and a bridge rectifier and some resistors and capacitors on the other.
After desoldering the components I tested the LED using an adjustable powersupply. The voltage was set to 2v and the current limit 20mA. I then increased the voltage until it started glowing. At 2.8v I had a workable brightness and at that voltage the LED was drawing between 3 and 5mA.
In the process of soldering these to some scrap PCBs, I discovered that the reason for 3 lots of connectors is that there are 3 individual LEDs in each package. I also discovered that some of the packages not all three of the LEDs were working. This might account for why the light failed in the first place as the original circuit seems to chain all the LEDs in series like Christmas tree lights. I'll likely need to re-measure the current now that I've worked out that there are potentially 3 times as many LEDs. If they take a lot of power then I'll use a PWM signal to dim them down a bit.
You might recognise the PCB if you are a Raspberry Pi Zero fan, it is from a batch of AverageManVsPi ProtoZeros where the silk screening failed quality control. I got them for the price of postage and they make great "tri-pad" boards for prototyping regardless of if you attach them to a Pi or not.
Once I've worked out the rest of the car chassis design I'll chop up the PCBs to mount them on the front of the car.
Brake Lights
In my box of electronic components I've a large number of 3mm red LEDs, I'm not actually sure where I got these but they have very short legs so I presume they came straight off a PCB. I've checked I've enough for a couple of sets of 6 LEDs to make for a nice bright brake light. The plan is to mount these on some stripboard or PCB similar to above.
Indicators
I also checked to see if I had any orange LEDs. I had 3 which was annoying as I'd need 4 for the indicators. However, I did have lots of white LEDs. So I designed an indicator block in OpenSCAD to be printed from some translucent orange filament that I bought the other year. I printed out a few tests and in the process noticed two things. Firstly that the light shone best where there was minimal infill I'd tried 40% and 8%. Also that my initial drill holes were so small that they just closed up. I realised that I could combine these two and have a zero infill to give a hollow box and then add some slits to force the slicer to add some extra supports for my screw holes. I also added a bubbly texture to the top to help diffuse the light.
https://github.com/Workshopshed/UpcyclingDesignChallenge/tree/master/3DModels
To test the light I inserted a white LED in the back and powered it from a couple of button cells. I'll print out the other three when I've a better idea as to how the bumper assembly will be put together.
Top Comments