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 1 Electronics Forums / Theory articles / Re: Using Thevenin's theorem on Wheatstone Bridge on: August 29, 2006, 09:16:58 PM Quote from: Zeppelin on August 23, 2006, 07:07:00 PMV8meathead, 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 2001Ah ha!  Thanks, I appreciate it.
 2 Electronics Forums / Theory articles / Using Thevenin's theorem on Wheatstone Bridge on: August 23, 2006, 01:01:18 AM What's the correct way to use Thevenin's theorem to find the current going through Rs?  I keep getting 5mA and it should be 3.33mA.  I can't figure out where my problem is.
 3 Electronics Forums / Theory articles / Re: Which one of these is correct!? (State technique for an electrical network) on: January 17, 2006, 04:37:44 PM Alright, awesome thanks
 4 Electronics Forums / Theory articles / Re: Which one of these is correct!? (State technique for an electrical network) on: January 16, 2006, 09:04:35 PM 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.
 5 Electronics Forums / Theory articles / Re: Which one of these is correct!? (State technique for an electrical network) on: January 06, 2006, 07:17:20 PM If anyone needs the full version of the professors notes here they are...http://www.engr.uky.edu/~ymzhang/EE422/EE422-7.doc
 6 Electronics Forums / Theory articles / Re: Which one of these is correct!? (State technique for an electrical network) on: January 06, 2006, 07:08:17 PM Click on them to view them better cause it's kind of hard to see the way it is. Here is what im talking about.   2 Different equations.
 7 Electronics Forums / Theory articles / Which one of these is correct!? (State technique for an electrical network) on: January 06, 2006, 07:06:07 PM 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!?
 8 Electronics Forums / Electronic Projects Design/Ideas / Re: Making LEDs turn on at a certain resistance on: December 20, 2005, 07:40:07 PM wayyy off topic, but where did you get the symbol for ohm?   Sry I had to ask.
 9 Electronics Forums / Electronic Projects Design/Ideas / Re: Working on 7-Seg Up/Down Counter. Bounce problem with push button. on: December 16, 2005, 02:14:37 PM Thanks for the responses.  Ill be giving these a shot today.
 10 Electronics Forums / Electronic Projects Design/Ideas / Working on 7-Seg Up/Down Counter. Bounce problem with push button. on: December 15, 2005, 02:48:32 PM 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.
 11 Electronics Forums / Theory articles / Re: What's a snubber capacitor, and what's it used for? on: December 13, 2005, 02:52:21 PM thanks for the help, this cleared it up.
 12 Electronics Forums / Theory articles / What's a snubber capacitor, and what's it used for? on: December 10, 2005, 06:48:51 PM Used to stop switching transients right?  Can anyone explain this in more detail?  Thanks.
 13 Electronics Forums / Theory articles / Re: missing some basic theory on: November 30, 2005, 02:52:12 AM Once you find the total current I(p).  And you want to find the current going through one of the two resistors.  Take... I(R1) = [R2/(R2+R1)]*I(p)  or I(R2) = [R1/(R2+R1)]*I(p).  These are called a current divider equations.
 14 Electronics Forums / Theory articles / Question about Ground Loops on: November 23, 2005, 01:32:01 AM 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.
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