Intro: Electronic Vehicular Robot
This Smart Tracking Robot Car was purchased from banggood.com. It was a nice cheap project to learn soldering and work with electronics without too much complication. The instructions from the website were subpar, so hopefully this helps someone out there attempting this project.
Have fun and even if you completely bungle it up, you're only out a few bucks!
Step 1: Gather Parts From Kit and Inventory Check
The first thing I did was open up the entire kit and look through everything. I just matched up the pictures from the site and made sure I had the proper count of each one. The instructions are in Chinese so that didn't help me much. Also, I didn't know how to read a circuit diagram, so that might as well have been in Chinese too.
I was to learn all about resistors, LEDs and photoelectric sensors in due time.
Things you need that aren't included in the kit:
- Soldering Iron and solder
- Small Philips screwdriver
- Wire stripper / cutter
- 2 AAA batteries
- Alligator clips (not required but helpful when testing connections)
- 3m doublesided tape (only if you stick when you ought not have stuck)
Proceed! Resistance is futile...
Step 2: Testing Resistors and LEDS
Do your future self a favor and leave the big stick-on things (motors, battery mount) off until later on. As you'll see, I learned this the hard way and ended up having to get some new doublesided tape...
This part I needed an instructors help with because I am wholly unfamiliar with resistors and the color scheme. If you want to learn: https://www.instructables.com/id/Resistor-Color-Coding/
In order to place the resistors properly on the board, it needed to be determined which ones were 51, 1K, and 3.3K (very granular color differences, see grainy picture). We tested them with a multimeter to determine which was which and then placed them into the board.
If you are as unfamiliar with LEDs as I was, just know that the long side is positive charge and the short side is negative. I remember it by saying you'll live longer if you're positive, and it hasn't blown me up yet.
Onward young solder!
Step 3: Solder
Soldering was what took me the longest just because I'm terrible at it. Protip: make doubly sure that you're plugged into the correct spaces on the board before you make it permanent. The kit is very good about having the shape etched so you can match it up. If polarity is a factor, that will be marked as well.
Here is a cheatsheet:
R - Resistor (12 total)
R1GR - Light Dependent Resistor (LDR) or Photodiode (2) Learn here
C - Capacitor (2 black battery shaped)
Q - Transistor (2 half moon shaped)
D - Diode (D1 D2 Red LEDs) (D4 D5 clear, light up along path)
IC - Integrated Circuit (BRAAAIIINNNSS - Zombie)
Sequence your soldering from low to high, the first with resistors, then onto the taller components. The instructions that I read afterwards say to place the photodiodes at 5mm height, but I was tired and soldered them at a height much closer to the board. This is what determines how it will track along the track (motor on or motor off) so I would assume they ought to be flush with LEDs, but mine works just fine.
You can connect the on/off switch and integrated circuit now as well.
After the solder cools, clip the excess but do so in a way where they are shot across the room like projectile needles. Do not point it at your eye whilst clipping. Target ought not be your own eyes unless you are sick of seeing.
On to "Wire I don't mind if I do..."
Step 4: Wiring the Motors
Don't stick the motors down yet!
If you are getting antsy, this is where you can stick down the battery compartment and run the wiring through the board hole.
To test direction*, I put in batteries and connected the wires from the battery directly to the motor leads to see which direction it turned. Now you can mark which post needs to be positive, and which needs to be negative. Make sure to place the motor in the orientation it will be mounted in order to make sure it is turning in the correct direction.
Once you are sufficiently satisfied, take out your batteries and solder your connections before sticking down your motor.
NOTE: The positive sharpie mark on the motor 2 is wrong. I zigged when I should have zagged.
The red wire is connected to the 3V positive power supply. There is plenty of extra wire, so the excess can be used for mounting the motors, clip and strip to your liking. I tried to stay consistent with the coloring of my wires, but you can use the extra included wire to make your connections.
If you haven't done so already, stick down those motors, check that everything is connected and get ready to have your mind blown.
On to the track!
*Another reason I had to unstick the motor was the direction of travel. DC motors work by moving in a single direction as the current passes through. If the polarity is reversed, the direction is reversed! Pretty awesome, but not awesome if you solder it wrong and your car just spins in an effing circle. This is purely hypothetical.
Step 5: Racetime!
If you've done everything correctly, when you put in your batteries, you can push the "on" button, place the car on the track and marvel at the magnificence of autonomous automobilia!
If it doesn't work, check your solder connections. I had a negative lead that was not making a good connection with the board therefore was leaving the circuit open. Once I resoldered that connection (removing the batteries prior of course), it came to life like Frankenstein's monster!
Congratulations! Elon Musk ain't got nothin' on you!