|
4.13.2004
Compared two circuits. The globe circuit does not have any feedback.
It uses a Hall effect sensor to switch the polarity of the magnet very
quickly. The online circuit uses feedback from photo sensors to figure
out the position of the levitating object and change the magnetism of
the solenoid appropriately. We are leaning towards using optics to sense
and either Bang-bang or PID control through circuitry.
4.15.2004
After consulting the masterful Gill, we decided to use Hall effect sensor
after all. The overpriced globe uses a single Hall effect sensor on
the top of the magnet. We are going to use a two linear Hall Effect
sensors to determine the change in magnetic field and thus the position
of the magnet. Looked up part numbers for Linear Hall Effect Sensors,
variable resistors, and op-amps. Kat is currently working on the website.
4.21.2004
Pearl started writing up the qualitative description of magnetic levitation.
Sarah and Kat used Experiments
with Magnetic Levitation site as a basis for the circuit design.
Lindsay danced her heart out at Babson Dance Ensemble, the whole time
contemplating the depths of our project.
4.22.2004
We realized we still have a whole lot of stuff to do. We ran the circuit
design past Gill and he tore it apart for us :-P. Important parts for
our circuit are the linear hall effect sensor, (MLX90215), op-amp (TL084),
diode (1N4148), potentiometer (POT...), transistor (IRF840A). Lindsay
looked into the hall effect sensor and found it at Digikeys, we are
waiting to approve this with Gill. Sarah worked on modifying the pictures
for the gallery section of the website. Kat and Pearl (after many difficulties)
cut the ferromagnetic rod that will go inside the solenoid.
Kat ninja
attacked Gill and they went over the control circuit once again and
simplified it even more. Yay! Now instead of comparing each hall effect
sensor to a constant then comparing the difference to each other, the
hall effect sensors are being compared to each other directly.
4.23.2004
After a nice EARLY morning Math class, Kat put the circuit schematic
into PSpice and also put it onto the website. Soon Kat will attack the
rest of her team mates and force them to look at linear hall effect
sensors. MUAHAHAHA!!11one
4.26.2004
We had a group meeting with Gill. We emailed the ECE stockroom with
an order of 5 different types of linear hall effect sensors and 10K
potentiometers. Pearl and Sarah constructed the circuit with the parts
we have.
4.27.2004
After an excellent discussion on the book The Moon is a Harsh Mistress
for TTGB porject class, Lindsay and Sarah figured out the layout of
our poster. Pearl is figureing out EXACTLY how our circuit works and
what every part does. Sarah is working on Photoshoping our poster.
|
