RC Car Updates 4/21. The Car is DONE!

Hey everyone!

I don't even know where to start! It has been over two months since my last blog post here. As you'd expect, I did get a huge amount of progress on the project in the meantime. Well, there is no way to describe it, but IT IS DONE!!!!

The last time I posted, I had just finished up the remote controller. Since then, I and my friend Jeff have been mostly working on the bodywork. We have drilled a rectangular hole on the front bumper where the license plate would go, and I mounted the proximity sensor there. I had originally ditched the proximity sensor idea, but seeing how well the paint was turning out, I wanted to have some sort of a way to preserve the paint job. After all, I will be giving this car to my 8 year old brother in a week's time, and just like any 8-year-old, he will definitely try to trash this car, BIG TIME! The proximity sensor is supposed to look out for obstacles ahead and brake the car if there is anything in the path. Of course, this doesn't mean that he can't just back it up into things, or sidesweep the car (hurts just thinking about it).

Well, as with any decent paint job, this one also started off with prepping. We sanded and sanded for hours until we could achieve a nice and smooth surface on the car. If you remember, I had bought the car second hand, so it was already dinged up and had scratches and cracks. To fix the cracks, we used Bondo just like you would on a real car in real life.

Jeff sanding away the imperfections.

Car with the black Bondo on the roof covering a crack.

Next, we did a little test layer. We wanted to see how good the metallic gray paint we had purchased was going to look on the car. So here is a picture of the first test coat.

So as you can see, we painted a small portion of the hood and concluded that paint was simply awesome, so then we proceeded to paint the whole car metallic silver. The paint was very nice, there were actual metallic particles that sprayed out with the paint that gave the model car a real-car look! Here are pictures of the car after a few layers of metallic gray.

I reckon we put at least 5-6 coats of metallic gray, if not more. We had to do a lot more sanding after putting the first coat because of some imperfections we noticed. After hours and hours of spraying, we were happy with where the car was. Next step was to mask off everything but the stripes. The stripes were really very very really tricky (I cannot express enough!). The two ends of the stripes had rounded edges and the hood stripe gradually increased in width as you went up closer to the windshield. So you can see why it was tricky. On top of that, we had to make sure there was no overspray that ended up on the metallic gray ruining the bottom layer. So masking was definitely not easy. Here is a picture of the car with the masked out stripe.

We used a special type of tape (the green stuff) that was apparently made for just our application. The tape is designed to create a sharp line between the painted area, and the masked-out area. And I would say that it definitely achieved that. The rest of the car was covered with Christmas-themed packing paper :)

Here is how the stripe turned out. It is simply brilliant! The pictures above were taken right before spraying clear coat. We noticed a couple of imperfections after spraying on the stripe. There was a bit of an overspray in the back but it was all sorted out by scraping off the overspray with a knife.

Next step was to spray on the clear coat. Here is Jeff spraying on the clear coat.

The clear coat gave the car a huge shine. We sprayed 4-5 layers of clear coat which made the car shine like the sun. See for yourselves:

The very final step was to put on the windshield, the headlights and the small bits here and there. As I put on more parts, the car just looked better and better. I am now bombarding you with tons of pictures that I took only a few hours ago.

The car is DONE...... Simply unbelievable. I have been working on it for over 14 months. Before I end this post, I want to thank my good friend Jeff for his tremendous help. I would not have been able to pull this off without him and his knowledge/resources. Finally, I want to leave you with this one circuit schematic, the schematic that started it all......

Original hand-drawn schematic of the H-bridge motor controller used to drive the rear wheel in the RC Car.

RC Car Updates 2/18 - What I have been doing for the past 2 months!

Hello Everyone,

I have had great progress since my last update. The PCB for the remote controller has been sent out to OSHPark and I have actually received the boards already. They are all soldered up and everything. I actually received the boards almost a month ago, so I have been meaning to make this post for over a month now.

Anyways, the board is all populated and I must say, it most certainly was a pain soldering all the SMD stuff on it. The MSP430 on the board is a TSSOP so that wasn't too bad, but the buck-boost converter came in a QFN package (Thanks TI....). In case you are not familiar with QFN, it doesn't have pins that stick out, it just has pads on the side and the bottom that gets soldered to pads on the PCB. There was even a pad on the bottom in the middle, so it was clear that I had to reflow that QFN rather than doing good ol' soldering with my Radioshack soldering iron.

Also, I must point out here that Newark (my supplier for electronic parts, awesome company) messed up my order for the first time! I have ordered boxes of stuff from them, and they had never messed up anything but this time, they sent me a 75K resistor instead of the 1.5uH inductor I ordered! The inductor is the current storing inductor for the buck converter so it is an important component. I soldered on the 75K resistor they labeled as the inductor, and of course the power supply did not work. For the life of me, I could not figure out what was wrong with the circuit. After many sleepless nights, I finally measured resistance across the so-called inductor and saw 75K resistance. Inductors might typically have a couple of Ohms of resistance across, but 75K is waaaayyy tooooo high! So I knew the inductor was not actually an inductor. I had an 0805 1.5uh inductor lying around the house, so I jerry rigged it to fit on an 0603 pad.

Anyways, here are some pictures from a month ago. Now everything is soldered, but in the picture on the bottom, I only had the bare minimum soldered.

Here are pictures of the board:

There are other SMDs on there that are just impossible to solder with my awful soldering iron, so Jeff to the rescue. He recently built up an awesome electronics lab in his house and has kindly let me use his equipment. He has a microscope for tiny SMD soldering (Awesome!), an awesome Weller fine-tip crazy-fast heating up $300 soldering station, an oscilloscope and of course a signal generator. There are also two tiny transistors that come in 6-pin tiny package that I use on the board, and I actually messed up soldering them big time. 

Jeff's Lab

Finally, I am sharing two videos, one of the controller with LEDs flashing, and the other with the RC Car driving around.

Thanks guys!