Assembling the roböcük robug kit
Date: Monday, November 04 @ 08:41:26 EST
Topic: Endtas Kitleri


An article you should read before beginning the assembly of your new, endtas-roböcük robot kit.





First, examine the components and the PCB (Printed Circuit Board) in the kit. If you are a beginner to electronics, try to get accustomed to the components a bit. Clean the component leads from sticky paper, glue remains etc. Be careful while doing this to avoid ripping of the leads.

For the assembly of the kit you will need the following tools.

  • Soldering iron (max 30 watt) and some solder
  • Chisel
  • Thin pliers

    Take your time while assembling the kit. Don't hurry. Read this article to the end first. The difference between obtaining a good working kit and obtaining a useless pile of soldered components is only a bit of uncarefulness and unnecessary hurry.

    If you didn't do soldering before, try a couple of soldering experiments on a multi-holed protoboard. Try writing your name with soldering wires on the protoboard and maybe you can try to assemble an other simpler kit to further improve your soldering skills.

    While soldering, try not to heat the component leads more than necessary. We have an article on soldering. Read it before beginning to solder your robug. Here is the article.

    There are two types of transistors in the kit. NPN type and NPN type BJT transistors.

    As the NPN, you'll find eight BC550 ( or BC547 , BC548)

    And for the PNP transistors, eight BC 557 will be found in the packet.



    Do not substitute the NPN and PNP transistors. Otherwise you'll simply obtain a nonworking kit. To prevent mistakes, separate the transistor types after taking them out of the packet and put them in two different places. While assembling, first mount the NPN type transistors, and then PNP type. Soldering one from a type and an other from the other type will increase the possibility of error.

    For the resistors in the kit, there are two different kinds. Twelve 470ohm resistor, and eight 10kohm resistors. Again, this two kinds mustn't be substituted. Don't hurry.

    We have an article in the x-files section about reading resistor color codes. You may also take a look at the color code tables in that article.

    Briefly, a coloured resistor is read as follows; hold the resistor, with the gold or silver color stripe at the right. Begin reading the codes of colors from the left. The first color is the first digit, second color is the second digit, and the third color is the number of zeros to be put at the end of resistor value.

    For example, a 10Kohm = 10.000 ohms resistor is coded like this;

    one - zero - three - gold or silver.

    one = brown
    zero = black
    three = orange
    gold = % 5 error tolerance

    silver = % 10 error tolerance



    The first picture is a 470ohm resistor with color codes, yellow, magenta, brown and gold.
    Second is a 10k ohm resistor with color codes, brown, black, orange and gold.

  • First Step. 12 resistors will be mounted 470 ohms each. Before mounting them, fold the leads according to the distance between pcb holes. All 470ohm resistors on roböcük1 will be assembled horizontally.



    After putting the resistors thru the holes on their positions, fold the leads from the back of PCB and shorten them. The leads must be short enough not to interfere with other leads and long enough to hold the resistor into its place. A lead around 1-1.5mm long is usuall fine.

    After the 470 ohm resistors, lets mount the 10kohm resistors into their places. There are eight 10K resistors and all will be mounted vertically. After putting them onto their places, the leads of them should be shortened like we did before.

  • Now you can solder your resistors. Care must be taken not to overheat their leads. Overheating may damage them. Usually a heating time of 3 or 4 seconds is ok. But no more. And additionally, with the increasing power of the soldering iron, the heating time necessary decreases. Use a soldering iron, not more powerful than 30Watts. Usually a 15-20Watt iron would be the best.



  • Don't trash the excess leads of the components. Later you will use some of them for mounting the motors and making two jumpers on the pcb. The 4 holes for the jumpers are located in the middle of two motors, between the two 4-transistor groups each drives a motor. The jumpers are clearly seen in the drawing below and expressed in the following picture with a red circle. The other red circle shows the details of motor assembly. Two leads of sufficient length will be put among the proper holes as seen in the picture and the tip of the leads will be bent from back to avoid their falling off.



    The details of jumpers on the pcb and motor assembly.

  • Now you can place your LEDs, bend and shorten their leads from the back. Next, carefully solder them.



  • The next step is assembling the transistors. First, mount the N type transistors and next, the P type transistors. Take great care of the shape of transistor drawing on the pcb and the shape of the transistor itself exactly in matches each other. Bend the leads from back. Shorten them and solder. Then mount the two capacitors which are close to the tail of the bug. Take care, these components are directional. They have got + and - leads and they musn't be placed wrong. The polarity of the leads are expressed on the body of the capacitor like in the following pictures.





    After mounting, bend and shorten the leads as usual. And solder them too.






  • And the next step is the assembly of the two small DC motors. Though these will carry the weight of the bug and move it around, should be strong and rigid enough. The motors will be mounted to the side of the pcb only their metal axises touching the ground like the feet of a real bug. The plastic gear will be mounted to the tip of the axis for assuring more grab . The paper labels on the motors must face towards the ground. IF NOT, the bug goes to wrong directions, backwards instead of forward or simply turns around all the time going straight for a few seconds only if it collides something. While mounting take care of the motor axis angle. It should be touching to ground with an angle around 45°. By means of this angled touch, the small diametered motor axis will act like a small wheel and will move our robug without any reduction gear on smooth surfaces easily.

    For mounting the motors, first two motor leads must be prepared by using the precut resistor leads which you didn't trash and kept a side ( didn't you? What a shame :( ) These leads will supply current to the motors and also will help them to strongly stay in place.

    After this step, you now have two motors with lengthened electrical connections which are ready to be soldered to the pcb.

    Put the lengthened motor leads thru the two holes with a Motor Sigh between them on the pcb and bend them from the back enabling the motors to stay in place symmetrical to each other. Solder the motor leads to the pcb. Now carefully check the position, angle and symmetry of both motors. Then carefully and firmly wrap the given thin-long wire around the motor passing thru the pcb holes around the motor in each turn. Work on this assembly until you feel it is capable of carrying the weight of the bug, with all components and batteries. Now solder the wire at the points which it passes thru the holes and fix your engines.

    A smooth surface is needed for your bug to operate properly. The speed of the bug is around 10 cms a second with fresh batteries.

  • Mount the small switch onto its place at the right aft side of the bug, next to the cell holder. You will use this switch to turn on and off your bug.



  • Place the cell holder into its place, bend the leads from back firmly and shorten them for proper fitting to solder area. And solder them.



  • A small ceramic bead is included in the kit package to be used as the back wheel of the bug. First make an axis from the attach-clip given in the kis to the bead and mount the bead onthe that axis. Solder it carefully into its place. If your bead is made of plastic, be careful not to melt it.

  • Now it is time to make your bug's feelers. You'll use the two small pieces of guitar wire and the attaching clip which you'll find in the packet. First, straighten the clips. Then cut two pieces 1.5cm each. By using thin pliers, give a P shape to the wire or any other shape which you think will work taking into account of the shape and position of sensor mounting holes on the PCB. Some details photos and renderings are as follows.



    Mount this P shaped ring into its place. Then mount the guitar wire onto the pcb and bend it in a manner that it suitably passes thru the middle of P ring without touching it. It must only touch the ring even if the bug collides something. Some sanding of the attaching clip is required before soldering.

    Now straighten the second clip and sand its tips before soldering. Then solder it to the tip of the guitar wire, forming a nice bug-feeler. You may shape it as you wish or even put additional eye-like beads onto its tips



    Congratulations. The assembly of your robug kit is complete. Now you can run your bug around after placing two batteries into the battery holder on the pcb. Take care of the direction of batteries. ;)





  • This article comes from Robotik & Elektronik
    http://www.endtas.com/robot

    The URL for this story is:
    http://www.endtas.com/robot/modules.php?name=News&file=article&sid=18