Hey Guys-
On Monday we learned about photoresistors and had a robot day! Photoresistors are light sensitive resistors whose resistance decreases with the amount of light falling on them.
We will be using photoresistors on our robots for the "Follow the line" competition and for "Robot Sumo."
We've all seen photoresisitors somewhere in our lives.....for instance my car as an auto setting for my headlights to turn on and off. When the resistor has enough light falling onto it, it causes electrons to jump into the next conduction band. The resulting free electron conduct electriciy, and therefore low the resistance of the resistor.
To use this on our robots, we needed to figure out the resistance range of the resistor for different light intensities. We used the 'white' of the our white boards and the black of non reflective electrical tape.
Once this is figured out, interface the resistors using voltage dividers to your microprocessor. The photoresistors will control one or both of your motors. You'll want to think about how you want your robotto behave for the line following competition and also think about what you want your robot to do when it faces the white outline of the sumo ring.
Oh...Mason also did some cool stuff in class...no he didn't light either of the Peter's on fire, but he put stuff in a microwave that shouldn't have gone into it, and made sparks fly.
Tuesday, May 12, 2009
LRC Circuits - 5/6/09
Today in class we had lots of fun with oscilloscopes and LRC circuits. If you haven't looked at Mason's AC circuits notes, I highly suggest you do or you might internally combust due to massive confusion. Mason's notes really helped me understand the vector problems in the HW.
We took a good look at phase angles and how to caluclate them and what they mean. Basically when looking at both current and voltage in an oscilloscope, current and voltage will both oscillate sinusoidally but not at the same time. The difference in which the current leads or lags the voltage is called the phase angle.
Phase angle (phi) = tan(-1)(XL-XC)/R = 2pi*delta t/T(dr)
Where T(dr) = the period of oscillcation of the driving emf.
Since it has been almost 10 years since I had to figure out the period of a function, I spent the entire class asking myself WTF? So it also might be really useful to know how to find the period;
Period(T) = 1/f
w=2*pi*f
We briefly went over the Root Mean Square Current and Voltage. Mason proved that the average current and voltage on always equal to zero, but the average power of the AC circuit is not equal to zero....ya we've all been zapped by AC circuit.
In general, your equations of Voltage and Current will look something like this for a LRC AC circuit in series;
If circuit is voltage diriven;
V(f)= Vmax*sin(wt)
I(f)= Imax*sin(wt-phi)
phi = phase angle
If circuit is current driven.
I(f)= Imax*sin(wt)
V(f)= Vmax*sin(wt-phi)
The circuit will still obey Kirchoff's rules.
Good luck on all of the H-dub!!
We took a good look at phase angles and how to caluclate them and what they mean. Basically when looking at both current and voltage in an oscilloscope, current and voltage will both oscillate sinusoidally but not at the same time. The difference in which the current leads or lags the voltage is called the phase angle.
Phase angle (phi) = tan(-1)(XL-XC)/R = 2pi*delta t/T(dr)
Where T(dr) = the period of oscillcation of the driving emf.
Since it has been almost 10 years since I had to figure out the period of a function, I spent the entire class asking myself WTF? So it also might be really useful to know how to find the period;
Period(T) = 1/f
w=2*pi*f
We briefly went over the Root Mean Square Current and Voltage. Mason proved that the average current and voltage on always equal to zero, but the average power of the AC circuit is not equal to zero....ya we've all been zapped by AC circuit.
In general, your equations of Voltage and Current will look something like this for a LRC AC circuit in series;
If circuit is voltage diriven;
V(f)= Vmax*sin(wt)
I(f)= Imax*sin(wt-phi)
phi = phase angle
If circuit is current driven.
I(f)= Imax*sin(wt)
V(f)= Vmax*sin(wt-phi)
The circuit will still obey Kirchoff's rules.
Good luck on all of the H-dub!!
Wednesday, May 6, 2009
Tuesday, May 5, 2009
STRIKE #3
Speaking of Monday, Mason wasn't here on Monday, but Peter, Me, Brandon, Chris Z., and quite a few others were there doing a little work on our robots. Well, Peter wasn't working on any robots, but he did do his SI session. :3
We took our tests last Monday, right? So... extra credit? XD
We took our tests last Monday, right? So... extra credit? XD
Monday, April 27, 2009
Wednesday April 22, 2009
Today was a relatively relaxed day in class. Since we haven't had a robot day, or even a robot half day, in a long while we dedicated the entire day to building robots. We didn't get to augment our toys with weapons yet but we did add some motors to the circuit. A mobile sentry is better than a fixed one right? We began by breaking up into individual tasks. The first task was to solder wires to the motor. The second task was reminiscent of our lego years in that one person must build the drivetrain. The final task was to attach the relay and transistor circuitry to the protoboard so the motors can be controlled in on/off (transistor) and forward/reverse (relay). Once all three tasks were completed they were to be joined together and tested for error. Not many groups got this far so it will be completed on monday after the test. The homework consisted of a practice test of problems from last years test, homework problems and freshly made problems. It was a relatively easy day to make up for the brutal one we shall have on monday. Good luck to everyone!
Tuesday, April 21, 2009
More magnets and electricity! Hey at least nothing was melted...
Hello everyone. This is my first ever blog post - that's right, first ever! I've never thought that my first ever blog post will be about physics but hey, you can't predict everything, right? I apoligize if the writing is bad/boring because afterall, I have never done a blog post until now!
So here it goes!
We started off first by getting the news that our last homework involved with chapter 28 instead of 27 only. Wait a minute, I thought that homework was on chapter 27 only. I guess that's why I did terrible on a couple questions (or maybe it was just me not realize that? Jeez...).
We then did experiements about Faraday's Law which involving wire loops and magnetic field. We found out that the more loops there are in the coil, the stronger the magnetic field of the coil is. Based on the results, we found out that the magnetic field of the coil is proportional to the current flowing through the wire and the number of loops there are in the coil.
We then learned about electromotive force, or emf. emf is from the potential difference generated magnetically. It's effected by the area, the number of loops, and rate which magnetic field changes (velocity) of the coil.
One thing that caught my interest at the end of the class was that Mason and Peter tried to demostrated something that reminded me about a phenomenon called Maglev, or magnetic levitation. This tech is used quite frequently in Japan's train system. Now, I don't know the exact detail of the system or the relationship between those two, so maybe professor Mason can explain a little bit about this? I know it's offtopic but I still find it rather interesting.
That's all folks! I hope you are still awake at this point after reading through all that! Celebration (?) is next monday so hopefully everyone is getting ready for it!
PS. Nerf offshore flow please. 100 degree weather in April is ridiculous 囧rz.
So here it goes!
We started off first by getting the news that our last homework involved with chapter 28 instead of 27 only. Wait a minute, I thought that homework was on chapter 27 only. I guess that's why I did terrible on a couple questions (or maybe it was just me not realize that? Jeez...).
We then did experiements about Faraday's Law which involving wire loops and magnetic field. We found out that the more loops there are in the coil, the stronger the magnetic field of the coil is. Based on the results, we found out that the magnetic field of the coil is proportional to the current flowing through the wire and the number of loops there are in the coil.
We then learned about electromotive force, or emf. emf is from the potential difference generated magnetically. It's effected by the area, the number of loops, and rate which magnetic field changes (velocity) of the coil.
One thing that caught my interest at the end of the class was that Mason and Peter tried to demostrated something that reminded me about a phenomenon called Maglev, or magnetic levitation. This tech is used quite frequently in Japan's train system. Now, I don't know the exact detail of the system or the relationship between those two, so maybe professor Mason can explain a little bit about this? I know it's offtopic but I still find it rather interesting.
That's all folks! I hope you are still awake at this point after reading through all that! Celebration (?) is next monday so hopefully everyone is getting ready for it!
PS. Nerf offshore flow please. 100 degree weather in April is ridiculous 囧rz.
Wednesday, April 8, 2009
Wednesday April 8th, 2009
Class is cancelled yet again. Sign in sheet is on the southernmost door. Early weekend!!!
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