Questions from the Electronics Tutorial
6:30PM 11/7/00 with Ari Benbasat
General Questions
What is Bipolar? Unipolar?
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Bipolar goes between Positive and Negative voltage.
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Unipolar is only 0 to Positive.
What is a Capacitor?
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2 plates, a charge acquires on one side, and repels the same charge on
the other side. In AC, it appears that a current is flowing.
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At a DC voltage, after a certain time, no more charge can be held on a
plate and no more current will flow across the plates.
How does a lowpass filter work?
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It lets low frequencies pass, and high frequencies get stopped.
Current is not very important in the digital world. Logic levels are important.
There is only 0 and 1.
555 Timer
lifted from http://hibp.ecse.rpi.edu/~connor/education/ElecInst_s99.html
Diodes
Every LED is a light emitting diode (a component that wants
to have a certain voltage across it. it will handle any current necessary
in order to get that voltage, usually 0.6V). If you put 1V across
the LED, it will try to put as much current to flow as possible. The 1V
source will probably not be able to source as much current as the diode
wants. So you need a current limiting resistor in series so that
you don't drain the voltage source.
Some notes on building a transmitter - receiver circuit:
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The transmitter is any piece of metal.
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On the receiver end:
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There is no concept of common ground so use a capacitor to absorb DC.
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How you pick a capacitor? Almost alwaysw 0.1uF, don't ask why.
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Diode to rectify the signal.
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Capacitor to integrate the voltage to some DC level that represents frequency.
See some other people's schematics.
Basic question: How you go from sensor input to needed output? It's
all about changing the signal.