DAGU, Line Tracing Car V2 Product Review

I purchased this kit car from Hobby King and had no intention of doing a product review until I was all but finished the build, it was great fun building it, took me back to when I used to build electronic kits on a very regular basis and I thought it is a fantastic starting kit for the young robot pilots out there. The kit comes complete, well 99.9% complete, you need to supply your own batteries which is best in my opinion. DAGU from China makes the kit and in Dagu form it is a well made kit and the price was very good, actually it was fantastic given what you get, $14.85AUD in my book is cheap but the killer was the freight, I purchased two items and it cost $22.90AUD to get them posted to Australia from China so the total cost was $26.30AUD when you share the post between the two items. On the plus side it only took 8 days to get here instead of the normal 20 plus days it can take.

                                   The Instruction manual DG-2000V2

The instruction manual is very good and easy to read given the English translation is at times a bit funny but good enough to totally understand. The illustrations are very good but you will need your glasses on to see some of the numbering on the circuit diagram. As always you need to read all the instructions first that way you won't make silly mistakes as you build the robot car like I did so be patient and read.

                                     The Line Tracing Car V2 Finished

                                               The Car from Above

The control circuit is built around a Quad 2 Input NAND gate (Not AND Gate) 74HC00 and two sets of Red LEDs and Photo transistors mounted in a plastic light shielding holders and is wired in a voltage divider network that can be set by two 500K variable resistors as they call them (potentiometer) and two C2120 NPN transistors wired to switch the negative side of each motor to earth. I added two 0.1uF capacitors across the motor power supply terminals (they didn't come in the kit) at the motor terminals to act as filters to help protect the transistors. The circuit is simple and it works very well, I set both pots to 0.8V and this setting worked perfectly first try, a bit of simple maths gave me that voltage from the 74HC00 data sheet that can be downloaded from the net, rough maths at that let me tell you.

                                 The Light Shield and 74HC00 NAND Gate

The only little bit that wasn't 100% was the polarity of the RHS motor wiring, it had to be reversed to get it to run the correct way but that is simple with permanent magnet motors you just swap the wires around and away it went, otherwise the instructions are perfect. The car is built on the PCB which forms the chassis and the gear set are open so you can see the operation of the gear train which is perfect for learning how a gearbox works. The complete kit is one of the best learning kits I have ever built, it's easy, fun and the finished product is fun as well.

                                      The Gear Train, Motor and Wheel

                                    The Rear Wing and associated LEDs

The rear wing has two Red LEDs and three RGB LEDs, the red LEDs are connected in parallel to the output from the 74HC00 that goes to the base of the transistor so it comes on when ever the LH or RH motors are working and the three RGB LEDs have a chip inside them that switches the LEDs through the three colours Red, Green and Blue at random and they are powered all the time and it looks fantastic as the car follows the line on the floor, table or whatever you set up the track on.

                             The Ball Caster, Axle Mount and Light Shield

You can see the Light Shield on the right in the above image, the Red LEDs were mounted in the front holes and the photo transistors were mounted in the rear holes and both were of different sizes so you couldn't make a mistake and it even had flats so you could get the components around the correct way when you put them through the holes, an excellent set up for the beginner. The other thing that worried me a bit was the metal ball caster, it was mounted on the printed circuit side of the PCB so I cut out two small bits of plastic and insulated the board with them just in case the caster rubbed through and shorted the circuit, I also didn't over tighten the mounting screws, just to be safe.
My final verdict of this kit is 8 out of 10 and I highly recommend it to the novice robot pilot, all you need is good soldering skills and the patients to follow the instructions and you will have a lot of fun with this kit and with the finished car. The Line that it Follows is simply Black Electricians Tape on a white surface, my kitchen table is white but you could use a few white cardboard sheets taped together and it needs to be used in a room with dull light for best results, so have fun, cheers.