Recent content by cjs94

Thanks for all the replies. I have some reading to do!

Sure. The right-hand side is the input stage of a PIC18, so CH = 10pF and RH is about 8.5k (for Vcc = 3.3V). The left-hand side, Vs = 2.11V and RS = 825k -- the actual circuit is a 4.7M/1M divider from 12V, I just simplified it to a Thevenin equivalent. Ca = 100nF. So, l.h.s. RC >> r.h.s...

Hi all, I'd appreciate help in calculating the voltages in the circuit shown. I thought it should be fairly straight forward, but it has me stumped. This is a sample-and-hold circuit for an ADC -- the switch is closed to charge the hold capacitor with the sample voltage and then opened to...

I'm reading about the Simplex method to solve a Linear Program. If a program is rejected as being infeasible, is there a method to identify which equations are causing it to be infeasible and a technique for reducing the program in an optimal way? (I'm not sure what 'optimal' is exactly, but my...

Uploading waveform image again, since the link in the original post is now broken and I can't figure out how to edit the post.

Thanks, but I was asking more about the natural effects of mass rather than its perception by an observer. My understanding of the Chandrasekhar limit is that if a star is below the limit then it will remain a white dwarf indefinitely, but if it is over the limit then it will start to collapse...

How close do objects have to be to be considered a single mass? On Earth, with solid objects, the answer would seem to be intuitive: if an object can't fall any further then it is 'connected' to, or part of Earth's mass. But what about something like a gas giant, or a star? I started thinking...

Thanks, I hadn't appreciated that sigma was not constant for a material. I'm looking into that now, but while I can see its dependence on frequency I can't see how it is affected by the geometry. Do you have any references which show how the first equation is derived and why it is a special...

I need to find the resistive component due to skin depth. I know the equation for skin depth and have been given the formula which relates AC to DC resistance for round wires: $$R_{ac} = 0.25(1+\frac{D}{\delta})R_{dc}$$ I need to calculate the AC resistance for a square and rectangular...

Hi, Can someone please explain how to calculate the A.C. resistance of non-cylindrical conductors? All the references I can find online assume round wires and I'm not sure the same equations would apply for other geometries? Thanks, Chris

Thank you, but I don't think I explained myself well enough. Assume for example that I am designing a 3rd order high pass filter. I have a few choices: I could make the filter under damped (Q<1), critically damped (Q=1) or over damped (Q>1). Is there any reason, any possible application where I...

Hi, Can someone please explain why you might choose a high or low Q factor high (or low) pass filter for a particular application? I can understand why it's useful for band pass and notch filters, for selectivity, but I cannot see any reason for it in a low or high pass. Thanks, Chris

Thanks for the replies. I've just had a response from the tutor, the question is wrong and my answer is correct. :)

Homework Statement This is one part of a wider question, I'm only posting the part I'm having trouble with. $$ \begin{align} \text{Given an impedance network } B &= \frac{Z_1 \parallel Z_3}{Z_2 + Z_1 \parallel Z_3} \\ \text{show that: } \frac{1}{B} &= 1 + \frac{R_2}{R_1} + j\frac{\omega CR_2}{1...

Hi, I'm studying the p-n junction and I'm a little confused about the depletion layer that forms. I understand how electrons and holes diffuse across the junction, recombine and leave charged ions but what I don't understand is why the ions remain fixed around the junction. Surely the...