Beginners: please read this post and this post before posting to the forum.
0 Members and 1 Guest are viewing this topic.
I am an AI beginner. I am doing the $40 Line Follower Robot from this sitehttp://www.societyofrobots.com/member_tutorials/node/59
I have successfully finished the robot.
1- When I set the robot for WHITE line follower by following this pic, both motors are on and running.2- When I set the robot for BLACK line follower as in this pic, both motors stop running.Is this normal or something is wrong with my circuit?3- Setting the robot for WHITE line follower makes the robot go forward all the time and never makes turns. Am I missing some steps?!!Please tell me what could be wrong with my circuit.
Note: I have attached a pic [...]
Not a bit AI about that.
Your light sensors are probably way off and you need to change the resistors making up the other part of the voltage dividers.
Measure the voltage at the common node in each pair (LDR and resistor) going to the IC
I like your project
measure the resistance or the sensors where they feed into the chip.
Adjust the potentiometers until you can get as close a match as possible
When you turn the trimmers, can you get the LED's to turn on over black and off over white?
Do you have a spare unsoldered LDR so that you can measure its resistance over black and white?
I measured the resistance of unsoldered LDR over black and white. Here are the readings.
If your blue LEDs are not glowing I would recommend looking at them to find out why.
This circuit is very light dependent. Maybe your don't have enough because the blue LEDs aren't on.
Too bad you leave us guessing at what range you measured!...
I'll assume it was on the 200kOhm range(?), so it's around 80k over white and 200kOhm and upwards over black.
keep the ones you have and add a resistor to each trimmer where it connects to the +9V line. Break the connection and insert the resistor in between.
Measure the voltage over the LDR with the trimmer in each outer position and report back your findings...
Well I am not sure how they are suppose to glow. Do they glow by using light? Can I test them by using a 1.5V battery? I already did but they don't glow either.
This is a picture from the tutorial. The blue LEDs are in the middle and are connected to the red and black lines. Those red and black lines are a power bus. They provide the power to make the LEDs illuminate.
How to measure the voltage over the LDR with the trimmer? Do I put the black probe of the multimeter over one lead of an LDR, and the red probe over a track pin of a trimmer?
Are they blue or IR LEDs (the latter you won't see with the naked eye)?Did you try swapping their pins, in case you had the polarity wrong?
Do you gave the part number for the blue LEDs that you purchased?
Your LDR's are of a higher resistance when in light, so the circuit have to be adapted for this.Either you swap the trimmer potentiometers for some 200k to 500k, or you keep the ones you have and add a resistor to each trimmer where it connects to the +9V line. Break the connection and insert the resistor in between.The trimmer will have much less influence if you just add a resistor, but it will be cheaper and easier.Start with say a 100k resistor and test if the trimmer can now get it in range.Measure the voltage over the LDR with the trimmer in each outer position and report back your findings
After changing all the trimmers to another ones with 250k, the blue LEDs are still not glowing! What is the problem?
Whether or not the blue LEDs glow has nothing to do with the trimmer.
How much voltage do you get between the anode and the cathode of the blue LEDs?
A bad connection for the ground wire between the main board and the sensor board my cause the problems you describe.
The Blue LEDs are not affected by the red LEDs or the trimmers. They are connected directly to the battery capacitor.
If the blue LEDs have 1.24vdc between their anode and cathode your battery is very low OR you have a problem in your circuit somewhere.
The red LEDs are on because the base of the transistors are high. You need enough resistance from the LDR so that the trimmer you put in will drop less then 0.7vdc.
I tested all my four blue LEDs individually with the 1k resistor and 9v battery they all glow. But when I put the four blue LEDs in series with one 1k resistor, they don't glow. Even with only 2 LEDs, they still do not glow.So is the problem with the LED or with the resistor? 1k resistor is what has been suggested in the tutorial.