Source Definition and 1000 Threads

I am wondering why we aren't replacing politicians (such as presidents of countries) by open source programs. Programmers would program several different programs and people would vote for them. To be eligible the program must pass through thousands/millions of different situations (like the...

Hello Everyone, Best wishes Am new to this forum. Please need a brand new suggestion for digitally controlled constant current source. I am designing this circuit for Plating thickness measurement. I have tried a several circuits based on Analog pot but would be helpful if i get with Digital...

Hi All , my landlord has been doing extremely loud drilling in the apartment right above mine. I have been recording it, but I wonder if there is a way to show that the sound was recorded in my apartment and not elsewhere (say in the street, next to a construction site)? Thanks in Advance.

Does light continue to travel through space after its source is removed?

Homework Statement I am trying to analyze the following circuit: "Note that if the two 2N5485s approximately match in their characteristics, not only is the voltage gain unity, but the DC offset is small: the constant current due to Q2 creates a constant voltage drop across R1. Furthermore...

hey! I want to contribute to the open source but i am unable to know the exact way, how and where should I do that. If anyone can help?

Homework Statement Write the KVL Equation for the outer loop Homework EquationsThe Attempt at a Solution The question above is a sample I have made for such a condition. The goal is not to find the value, but only write the correct equation. If an independent current source is connected in...

As I'm sure I've mentioned before, I've heard people say that stress and pressure terms in the energy tensor act as a gravitational source, but I don't understand how this could be, given that these terms can simply appear or disappear (in a non-stationary situation), unlike energy and momentum...

Homework Statement I'm to use source transformation to find the current through the 24 Ohm resistor 2. The attempt at a solution I used source transformation on the left 12V source and got a .5A current upwards. The 24 and 30 ohm resistor are in parallel so I found an equivalent resistance of...

This is more of a theory question than a homework question...but could a circuit consist solely of a voltage source and a current source? What I mean is a very simple circuit with a voltage source of Vx and a current source of Ix, connected in series. No resistor anywhere. Could this work? And...

Hey guys, I've recently learned that magnetism is an electric field viewed from a different frame of reference and that the mathematics of electrodynamics describes this. However something raised my eyebrow which I wasn't quite clear on. If energy is put into a net flow of electrons, the...

Homework Statement VOUT, they mean DC Homework Equations See picture, r0 is neglected also lambda (channel modulation) The Attempt at a Solution I calculate I DS with the formule given: 0.400*(0.5)²=0.1 mA IOUT = 5/25000 = 0.2 mA So the current source has got to be 0.1 + 0.2 = 0.3mA...

Homework Statement Use nodal analysis to find ##V_o##. Homework Equations ##\sum I = 0## ##I = V/R## The Attempt at a Solution So the book started throwing voltage sources into nodal analysis and I'm a bit unsure about this problem. The answer is listed as ##V_o = 3.89 V##. All they...

:(as a student, any help would be appreciated.

Homework Statement I'm supposed to find the current in a circuit with a voltage source, capacitor, and resistor in series. The voltage source is described by V=V0ejwt. Here, j is the complex number j2=-1, and i is the current Homework Equations I=C*dv/dt The Attempt at a Solution I have...

Hi everyone. I'm working on getting together some notes on school maths and of course I'd like to include some diagrams. The usual stuff, graphs of things like parabolas, circle geometry, etc. But I'm also skint. So I'm looking for some open source programs that can do that, and they need to be...

Guys, this seems very trivial yet I can not come to the correct answer and I've searched everywhere. I am asked to find the node voltages using nodal analysis. The trouble is I don't know how to express a current in a brach between 2 unknown voltages where there is an independent current...

How can current source be implemented? I think the source of current is the battery itself (due to potential difference). Plus current source has its own symbol. If battery is the source of current then does current source refer to the battery?

Homework Statement A circuit problem and I think a picture could do a much better job than anything I could type. Picture should be attached below if I didn't screw it up. Homework Equations I'm allowed to use Ohm's Law, resistor series/parallel combinations, superposition, Thevenin's...

Homework Statement the voltage Vc in the figure is always equal to 2 Relevant equations The Attempt at a Solution From kirchhoffs law, -Vc+4+5=0 Vc=9 V will Vc always equal to 9 V or it will vary?

I wonder to know what would happen when we use two flashlight in a same direction. by doing so, do we extend the range of light? if so, does it mean if the lights cross each other in a point perpendicularly the range that the light can traverse is going to reduce ? I have been said that if we...

Homework Statement Find is of the circuit below Homework Equations i=V/R v1+v2+..=0 is=vs/Req The Attempt at a Solution Resistance of circuit as seen by source = 7kΩ 6V(source)/7kΩ(Req)=.857i My question is, how come i3 is also 0.857i? Shouldn't it be different since it just...

Homework Statement I'm doing a practice problem and I'm asked to find source voltage and source current of the circuit below. Homework Equations i=v/R i1+i2+i3..=0 (KCL) v1+v2+v3..=0(KVL) The Attempt at a Solution So I started by calculating the current for the 2kΩ resistor, which I...

Suppose I have a 10kW input. I want to divide the 10kW into two separate sources, like 1kW and 9kW. What can I do to separate the input into these different ratings?

http://en.wikipedia.org/wiki/Schr%C3%B6dinger's_cat I don't understand, if the radioactive source is put in there then of course the Geiger counter will detect radioactivity so we know the cat must be dead?

Hi I've tried to solve the following circuit using Kirchoff's laws but i get wrong results.I know that because I've got a different solution of the same excercise.I've attached the image.My question is what are the equations of Kirchoff's laws because I try this over 2 hours and I can't figure...

Hello I need a source to power ADSL router when the electric power would be cut for any reason because i need to keep my laptop that i use for work connected to the internet. I found this "Anker® 2nd Gen Astro Pro2 20000mAh 4-Port Aluminum Portable External Battery Charger with 9V/12V...

Hi all, first post on PF! I was just wondering if a motor that is specifically designed to generate the most friction possible would be useful for heating purposes. If it's just wishful thinking, feel free to say so and explain why. Thanks!

I am a freshman (ore med). My curriculum does not have physics until junior year of college. I want to take the MCAT at the beginning of junior year. I am reading the AP Physics textbook of my high school (I didn't actually take AP Physics, I just bought the textbook) and while I am learning a...

Some of my advanced chemistry students would like to try this pharmacokinetic model circuit outlined in an AAPT publication (Cock & Janssen, The Physics Teacher, Volume 51, Issue 8, pp. 482-484 (2013)). It is a simple RC circuit, but I've never built a constant current source and am unsure of...

ZapperZ submitted a new PF Insights post Why You Should Not Use Wikipedia As Your Primary Source Continue reading the Original PF Insights Post.

Homework Statement the observer is stationary , but the sound source is moving towards the observer , i was told that the speed of sound relative to the observer doesn't change. why is it so ? in my opinion, the speed of sound relative to observer changed . because of v= f x (lambda) , as...

I am studying thyrisors right now. I am really struck at trigger circuit . The book shows gate source voltage and gate chathode voltage as two different things. I fail to understand the difference and significance of them. Please help me out .

Hello! I am a bassist in a rock band and I hace slight issue with trying to rig up this "this" http://www.newegg.com/Product/Product.aspx?Item=N82E16811992011 LED Controller to do its color changing awesomeness while pulsating with what is coming out of an output on my amp (which is a...

How are constant current sources different than any other source? Also, would they really have a constant current in any situation? Even when back-emf is induced? Can anyone explain the use of a constant current source, and how different they are from other sources?

please delete this post Hello, Accidentally I have noticed a strange behaviour using two different magnets, which I would like to discuss. The picture shows a disc magnet (shown also in the right to see the magnetization) with it's N facing upwards. Onto the disc magnet N side, a cylinder...

Homework Statement In essence, I'm trying to make a model of how the heat from a point source diffuses through air. It should be a function of both distance and time (I'm assuming either a 1/r^2 or an exponential dependence on distance). Homework Equations I found this equation...

I found some open source code in wx that I'm considering re-writing in qt and adding some new functionality to. It's for science research. Before I do, I wanted some feedback from the community if this is a worth while endeavor and an estimate of how long it would take. It's about 700 lines...

Hi, I'm having a strangely hard time imagining how the distribution of particles would look around a constant point source in some scenarios. I came up wiith something that sounds reasonable to me, but would like a logic check. The easy one for me to grasp is distribution when the source...

Homework Statement A point source in water provides 10 W of heat for 10 seconds, and is then shut off. The surrounding water has a temperature of 20 °C. Provide the temperature profile as a function of distance r and time t. Homework Equations The Attempt at a Solution If it...

Ok so I recently read this article (http://www.extremetech.com/extreme/184280-focus-fusion-has-cheap-clean-earth-saving-fusion-power-been-right-under-our-noses-all-along). This gave me a few ideas and a few questions. I would like to create a smaller version of this setup to fuse deuterium into...

When a circuit is being alimented by AC this means that exist in the circuit a voltage source that is generating the AC or exist a current source that is generating the AC?

Hi everyone, I'm building a white light interferometer and need help choosing and finding a white light source. I'm using this mirau objective: http://www.edmundoptics.com/microscopy/infinity-corrected-objectives/nikon-interferometry-objectives/59312 Here is the setup: I know...

Which is the real interpretation for current source? Exist some device or electrical object that acts like a current source?

Hey all, I'm working on the JUICE mission (Jupiter Icy Moons Explorer) and I've been tasked with finding software (preferably open source, but paid is fine) that can optimize circuit network designs that I upload. Originally I was trying to find programs that would run optimization using the...

Hey guys, I have been trying to design a constant current source that has a digitally controllable (μcontroller) range of maximum current outputs. Ideally the source would be able to be adjusted from .25mA to 2mA. The input voltage for the source would be in the range of 9 to 14 volts. Also I...

I'm looking for the source for the QM interpretation of "shut up and calculate". I thought it was synonymous with the Bohm theory and that I had seen it in Shankar or Sakurai. Yes, I Googled it and found David Mermin, and some other dude named Tegmark that I'm won't to bring up lest I...

Homework Statement The problem - confirm that the amount of radiation measured from a source is related by inverse-square to the distance. Here is a graph of my data fitted to y = a1 * x^a2. Every point is an average of 3-8 measurements (as many as needed to have a statistical error of...

For this problem, I added in an external source, and found an expression for the external current in terms of ix. Then I divided Vex/iex to get the Rth. Then I did superposition to find the Vth. I had some troubles getting rid of the extra currents, particularly i3 and i2. I was wondering if...

Homework Statement Image Homework Equations Current divider The Attempt at a Solution The only thing I see is that I solve for R1 and R2 for t < 0. Other than that I'm confused and not even sure I'm right about solving t<0.