Power Supply

It's been some time now since my last post. I was a little busy with work related matters and a trip to Japan which consumed all my time. This post is rather coming a little late as most of the work in this post was done some time ago but I didn't have the chance to document it.

So, Power Supply. The car does require some powerfully power supply that has to be battery based. the motors do require significant amount of power (current) to make it role. Using regular alkaline batteries is one option, but they will get replaced frequently which can be expensive. The SmartCar has a motor for each wheel which sums up to 4 motors, the missile launcher has three motors but only two can run simultaneously, this makes it 6 motors and we are not yet done, there is the processor, echo distance sensor and the wireless Joystick.

Above you can see how I plan to construct everything together. The missile launcher will be placed in the front and the power supply on the back, in the middle the main board with main processor and the supporting circuit for the missile launcher. Currently I'm using regular batteries but I will changing the power supply to Li-Ion batteries.

For now, every attempt to power the entire car with the power supplies failed and in all cases caused either the main processor to reset or the wireless Joystick to loose sync.

Oh well, I still need more lab work to find the correct configuration and I will probably need to add a small circuit for regulating 5V from the power supply.

The first measurements I did with a 9V battery showed that a current of ~60mA was required to power the main circuit (the main processor, the Echo Sensor and the Wireless Joystick connector). the 9V I had can't really supply too much current. Connecting a Voltmeter to the circuit showed the voltage getting dropped on the battery. Adding capacitors did help, but did not solve it, it only delayed the effect.

What I really want is to power everything from only one battery source. Currently I used two power sources, the 9V battery to power the main processor and the 4x1.5V batteries (6V) to power the motors.

I'm still waiting for my Li-Ion batteries to arrive and hope it will do the job, so for now I'm on hold for the power supply - I will do some more tests to ensure that I have everything ready until I get the Li-Ion batteries.

Now to something different:

Let's move to the missile launcher. First thing is first, let's remove the guts of the missile. 

The main board had the wires of the motors soldered to it, so I took a wire cutter and snapped them loose.
I then took a ribbon cable of 16 wires. Why 16?
3x "2 wires for motor"
5x "two wires for motor trigger"  (left, right, up, down and missile launched)

I really could have used only 11 wires if I really wanted to and everything would have worked just fine. All the motor triggers can be connected in daisy chain common ground wire for one end and the other end is really the trigger. As the missile motor does not require an H-Bridge one end is connected to ground so you also save another wire.

One of the best inventions is the Hot-Glue, it simply makes your work much easier. I used the Hot-Glue to stick everything together and keep them in-place.

I made sure to label all the wires to know which goes to which.

Above is the final product. The supporting circuit has been designed but still not built. Making a prototype PCB is really time consuming. It takes me around 3 hours to create one.

I'm dumping more picture of the SmartCar just to give a sense on how it looks right now.

Above is the supporting board for the Car Wheels.

Above you see the Wireless Joystick connector