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Posts posted by V8meathead

  1. V8meathead, I know what you're doing wrong:

    When using Thevenin to determine the current through Rs, you need to find an equivalent thevenin source for the rest of the circuit (the red block), this consists of Vth & Rth. For that you need to figure out the open circuit voltage & short circuit current at the terminals of Rs. 5mA is the SC current; it's not your final answer! Find the thevenin parameters as above & replace the red block with the thevenin equivalent source, then calculate the current through Rs, it is 3.3mA.

    Ref: Nilsson & Riedel, Electric Circuits 6th edition 2001

    Ah ha!  Thanks, I appreciate it. :D
  2. Sorry to go off topic here but how do you go about getting solutions manuals for textbooks?  Is there an easy way to do it or find them?  I always wondered where the hell people got these things from. ???  Like could I get one for my Signals book by John Wiley and Sons publishing?  I just feel like the kid who got left out when it comes to these sort of things cause everyone seems to have one but me.  :-\

  3. Thansk for your help!

    I was mainly asking about how they did the current loops for the middle circuit. The main thing I was having trouble with was the defined capacitor polarity in the middle.  When I run my loops in a clockwise fasion like the professor I get different equations from that signals book.  But I think when you throw them into that matrix I'm pretty sure everything turns out to be alright.  The thing that was confusing me is that they ran their loops in 2 different directions for the middle loop, which is why you get 2 different equations. 

    I was just curious as to why you define a capacitor polarity across the middle capacitor, but non of the other components.(I know you do it, I just can't remember why)  Im just having a brain fart!  I also realize it's a second order circuit.  Sadly, I've solved handfuls of these in class and can't remember the basics. :P 

  4. Alright 2 of the same circuits.  One is from the signals and systems made ridiculously simple book that was posted on here.  The other one is from some professors notes I found online.  They get two different equations. >:( Which one is correct and why!?  How do you figure this thing out, because I am confused as hell. 

    The first picture is from the professor.
    The second is from the book. 

    They take a KVL equation around an RLC circuit and come up with two different equations.  Both assuming the same sign convention.  Maybe it's me that's screwed up. ???

    Can someone help please!?



  5. To begin, my friend was building an 7 seg display counter using a programmable logic chip the other day.  He was using a push button to control the pulses going into the PLD.  We obviously had a bad bounce problem with the push button, but sometimes we could get it so all the numbers would sequence like they should(1,2,3,4,5..etc) with no jumps.  In order to get a clean switch, I tried 2 things.  I first tried an ordinary debouncing circuit using a 555 timer, and then when that didn't work right, I tried a one-shot multivibrator using the same 555.  What was happening was the numbers would jump on the seven segment.(i.e. 0,2,3,4,5,7,9, repeat) always skipping the same numbers(1,6,8) as it sequenced.  I thought maybe there was still some bounce issues or something so I tried it as an astable MV.  Same thing happend, it would sequence through skipping the same numbers. ??? I looked at it on the scope and it looked fairly clean but I am no expert. 
          To make a long story short, I still can't figure out why it's happening.  I can at least occationally sequence through all the numbers using the push button.  But when using the 555 it skips numbers.  Usually the same ones over again.  There must be some reason why it's doing this, but it's beyond my current knowledge.  Anyone know what's going on?

    Any help is appreciated.  Thanks. 

    EDIT:  Also, the PLD is programmed so that it counts up only as the rising edge passes.  0 to 1.  Not 1 to 0.  Or in otherwords +dv/dt not -dv/dt if that helps.

  6. Well I've searched Google, and wikipedia.  I have a pretty good idea of them.  But I need some more examples or something.  I guess I'm not really picking up on the idea fully.  Any of you guys have any information on them that could help me out?  Practical stuff or Book stuff.  Doesn't matter to me.  Thanks. 8)

  7. thanks Ldanielrosa and Alun. :P

    actually wait a second.  I actually didn't use a regular transormer.  I used one of those 3 prong, variable voltage transformer things that can supply more current and has higher voltage ratings than a regular function generator.(smaller boxy thing and heavy as hell) I pluged it into the wall and threw together the leads off of that.  I thought that current was the case.  But your probably right considering my explaination does sound a bit weird.  Do they share the same ground then too? the scope and big transformer thingy?  I seriously don't know.  If you wouldn't mind explaining to me a little more I'd really like to understand it.  Sry for wastin your time lol ;)

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