Making A LDR Robot Which Works on Commands with the help of a Smartphone

 Making A LDR Robot

• A Light Dependent Resistor (LDR) works on the principle of photoconductivity. The Light Following Robot's working principle is called as PHOTO-TAXIS.
•  Photo means Light, The robot moves towards the brightest light source. It uses two LDR (photo resistors) and two transistors - one for each motor. 
• When light falls on LDR's the circuits resistance drops down and through the Transistor approx. 1Amp current flows thus the motors rotate and the robot moves.

Hardware Required

1. Connecting wires
2. Stripper
3. 2 nos. NPN BC 547 Transistors
4. 2 Light Dependent Resistors
5. Paper Circuit Template
6. Copper Tape
7. Soldering Gun
8. Soldering Metal
9. Switch
10. Hot Glue Gun
11. Small Screws 4 nos.
12. Caster Wheel
13. Big Screws 7 nos.
14. Nuts 11 nos.
15. Metal Chassis
16. Paper Tape
17. 60 RPM Motors 2 Nos.
18. Robot wheels 2 nos.
19. Cable Tie 2 nos.
20. 3-D Printer
21. 4 V Batteries 2 nos.
22. Battery Holder
23. Drilling Machine

Procedure

1. Cut out the paper circuit template from the A-4 size paper. You can find the paper circuit by clicking on the link .https://acrobat.adobe.com/id/urn:aaid:sc:AP:a9fd1e48-7680-499a-8ef9-b281adabb0ea

1. Next, paste the copper tape wherever there are dark lines on the paper circuit template. Check the connectivity of the paper circuit using multimeter. For better connectivity, solder the points where two copper tapes meet.
2. Now, attach one LDR to the left hand side of the paper circuit. Make two holes on either side of the copper tape. Insert the LDR in such a way that its top surface should be facing on the back side of the paper. After adjustment, press the LDR to make it hold tightly with the paper. Cut the extra terminals of the LDR and then solder it to the copper tape. Similarly, attach and solder the LDR on the other side as well!
3. Next, we have to attach the NPN BC 547 transistors on both the sides. On the left side, turn the transistor 180 degrees in your hand and solder its terminals to the respective copper tapes.
4. On the right hand side , the transistor should be attached and solder straight, as it is, to the copper tapes. While soldering, see to it that the transistor does not over heat and hence it stops working.
5. Further, solder the negative terminal of the battery holder to one terminal of the switch. Take another wire , connect one end of the wire to the second terminal of the switch and the other end of the wire should be connected to the center copper taped line.
6. Next, connect the positive terminal of the battery holder to the topmost horizontal copper strip which is connected to both the LDRs.
7. Take one motor of 60 RPM. Connect two wires of same adequate length to both the terminals of the motor by the help of a solder gun. Now connect one wire of the motor to the opposite transistor and one wire should be connected to the center copper strip which is connected to the second  terminal of the switch. You are expected to do similar process with the second motor and attach it.
8. The paper circuit is ready.

3-D Printing The Phone Stand

• Design the structure on which your smartphone can be kept using tinkercad. It should be as given below:
• 3-D print the phone stand. It takes around 1 and half hour to be printed.

• Further, paste the paper circuit on the smartphone stand in such a way that , both of the LDRs are on the front and all the other circuit should be hidden behind the stand.
• After pasting the circuit on its stand, apply hot glue on one end of the switch and paste it on the top of the left hand side on the phone stand.
• Further, apply double sided tape under the battery holder and stick it on the other panel of the phone stand.

• Now, attach this phone stand to the red chassis. Carefully, drill 4 perfect holes in the phone stand where the 4 small screws and nuts can be attached and tightened on the chassis.
• Similarly, attach both the motors on either side of the of the chassis using the big screws and the nuts.
• Further, attach the wheels to the shaft of the motor.

You can use the gyroscope voice command app to command your LDR robot and make it work. Keep the phone on the stand, command the robot and the LDR robot would work as you say!!