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Random helpful notes for your experiment:

1. Some important equations/ideas/concepts:
   • The voltage across a capacitor varies as:
     V_c = V_o( 1 - e^-[t/RC] )
   • The current varies with time as:
     I_c = I_o e^-[t/RC]
   • The time constant for an RC circuit is:
     t = RC
     where R is the resistance of the resistor and C is the capacitance of the capacitor in the simple circuit shown in Figure 2.
     
     The time constant has units of TIME... so if they ask what the voltage is after, say, 3 time constants, what they mean is what does the voltage look like at t = 3t = 3(RC)
   
   The curves for both voltage and current are exponential for a capacitor; the voltage curve is an exponentially increasing curve whereas the current curve is an exponentially decaying curve (please check Figure 3 on p. 65).
2. Key to keeping track of filters and what they do:
   
   

   Filter	What it blocks or passes	Alternative Name
   High-Pass Filter	Blocks low frequencies	Low Filter
   	Lets high frequencies pass
   Low-Pass Filter	Blocks high frequencies	High Filter
   	Lets low frequencies pass

   
   When it asks you to guess what the graph of a composite filter (made of two (or more) filters) should look like, simply draw what the composite filter would look like (the one that does what they want). This might seem confusing but it's only relevant to the last 2 questions: just draw what a composite filter that does the action they require would look like; don't draw the 2 (or more) filters individually... just a graph of the single, composite filter. Don't worry, this part will make more sense in lab...
3. There's not much else to say about this lab... everything's pretty straight-forward and it should be pretty quick. There're just a couple of notes about the specifics of the lab that might be good to keep in mind:
   • Current leads the voltage by 90^o in a purely capacitive AC circuit.
   • A line filter only blocks ONE frequency, n
   • A band-pass filter blocks ALL frequencies except the one frequency, n
   • One important note: please be sure to track units, especially if you're supposed to be setting/using Hz or kHz. E.g., you're supposed to use/block the 60 Hz signal and NOT the 60 kHz signal.
   • Please be sure to power off the pre-amp when you're done using it (and the optical isolator, too).

1. Minor errors in the appendix.

Required Materials:

1. Laboratory Manual (SGM 407)
2. Laboratory Answer Book
3. Calculator with statistical functions

1. This lab is most likely going to be really quick. The slow part will probably be the check-out process so try to be the first to finish if you want to get out really early. I'm going to try to start checking your answers while you do the lab to see if that speeds up the final check-out process.
2. Remember, the 1^st midterm is coming up on 2/29/00 from 5-6:30pm in THH 201. I'll be posting more info and hints/tips as we finalize the details.
3. Feedback on if you're finding these pages helpful (or not) is definitely good. So if you have any strong opinions, or, dare I say it, ideas on how to make this better, drop me a line!