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  1. Merlin3189

    doubt in time shifting the signal

    I think that you are a bit confused with your symbols. x(n) is a function, where x(-3)=0, x(-2) =1, x(-1)=1, x(0)=1, x(1)=0 or x(n) =1 for n in {-2,-1,0) else 0 If you now say w(n-2) is 1 for n in {0,1,2} else 0, then you are defining w(n) to be the same as x(n). You are saying When n=-2...
  2. Merlin3189

    discrete signals

    How about radioactivity. Particles are emitted or not, at random times. We can integrate this signal to provide a count, then differentiate it again to provide a rate, but the original signal is as discrete as you can get. There is no part of a disintegration and (I think) the time for it to...
  3. Merlin3189

    Tips for learning recursion?

    Just a quick question for Kris. Your anagram prog: does it look up to see if words are in a dictionary or just find all the permutations of letters? I ask, because if you do, I wonder where you got your dictionary word list from? Or where your program can look them up online. Regards. Don...
  4. Merlin3189

    Incrementing Slice in Python?

    Right. Now I have it with correct indentation, I've run it myself and it's ok. Thanks for the link. I'll try it. I've been thinking about doing a bit of coding for fun, but had no particular ideas to try. Your questions have at least got me to fire up an interpreter and have a go again. I...
  5. Merlin3189

    Incrementing Slice in Python?

    Have you tested it? I haven't, but I don't think it should work when s1 is shorter than s2. Is there an indentation error here? Isn't the 'while' loop to be executed only if the "if" is true? If so, the other while loop is also wrong. Apart from that, it looks as if it should work. There...
  6. Merlin3189

    Incrementing Slice in Python?

    Yes, I think you are approaching it wrongly. You are not creating a new string, simply printing out the elements of that new string. (Though having looked at the Python documentation, it may be that you do create a string when you use print, but it is not accessible to the rest of the...
  7. Merlin3189

    basic of control system

    0 - I think the original question is referring to linear control systems. 1 - The low pass nature of real linear control systems is due to their being causal: you input a signal and what happens is a response to that, so it happens later than the input. So there is a delay in the system or lag...
  8. Merlin3189

    Function Generator Internal Resistance Theory

    Can I firstly congratulate PB on writing a question which is much clearer than many asked here. but I think here they are asking, what is the numerical value of Vr Saying Vr=Vs - IRi is not an answer, because you do not know what I is. When they asked earlier for an equaton for Vr, it was not...
  9. Merlin3189

    Induction cooker pans?

    Yes, that's the conclusion I'm coming to. Fine on the reluctance, the reciprocal of permeability, which I've used. Like talking about conductance and resistance. So we're happy that we need low reluctance, and I'd say low resistance as well, with the low reluctance being most important. Looking...
  10. Merlin3189

    Voltage Divider +12V, -12V, Ground.

    Ratch - great summary. Tried all three now and Laplace's method (Kirchoff 1 ?) seems neatest to me. Your method (Kirchoff 2?) gives me more or less the same equations as I used, but in two fell swoops (instead of 4 half swoops!) All I can say is, you guys must be more in practice than me. I...
  11. Merlin3189

    Induction cooker pans?

    Duke - Yes. Shielding + good conductors go together, though electric field shielding may also be a reason. I know you're right about the coils in Al cans - I've seen it. But my recollection was the can was quite large. I suspect you don't want too much eddy currents around an RF coil, it...
  12. Merlin3189

    Induction cooker pans?

    Hi Adam, thanks for the continuing interest. As I said B4, this is a can of worms. There are several factors all of which interact and it's hard to work out which apply or which dominate. I suspect you are right here. Another WikiP article says, "Skin depth also varies as the inverse square...
  13. Merlin3189

    Induction cooker pans?

    Just to add a link about Eddy's currants. WikiP has, (my underlines) So the emphasis for eddy currents seems to be that you need a good conductor with as low resistivity as possible. (Though what happens with a superconductor - infinite current and no power!?) BTW, another WikiP on...
  14. Merlin3189

    Induction cooker pans?

    Eddy currents is what I thought, but that's why I thought it should be Copper or Aluminum - a good conductor. Yes. I found one of those and it said it was made of Aluminium and Iron, though it didn't say how the metals were arranged. Well this gets right into the can of worms! Skin depth (a...
  15. Merlin3189

    Voltage Divider +12V, -12V, Ground.

    Well, if you did that easily, then it's me who's a bit dense. I couldn't do it without drawing 3 diagrams, over a page of scribble and using a calculator. With those values, even calculating parallel resistances needed a calculator. My method was to redraw the cct to suit me, then split it...
  16. Merlin3189

    Making two if Statements work at the same time

    Thanks Kris. Yes, I see. I had misunderstood his question.
  17. Merlin3189

    countdown timer

    I'm looking at this, but I can't quite make out the pin designations on your diagram.
  18. Merlin3189

    Making two if Statements work at the same time

    I think the answer to your original question may simply be, you can't! If you have to do two separate tests then they can't be done together. Equally, if you have to have two separate output commands, then they have to be done sequentially. However, if both sensors can be read by reading a...
  19. Merlin3189

    Voltage Divider +12V, -12V, Ground.

    Have you come across the Superposition Theorem before? It helps with the analysis of circuits with more than one voltage source. And just get rid of the red circled Voltmeter and it's wires. It's a distraction, until you have solved the circuit.
  20. Merlin3189

    Induction cooker pans?

    Thanks for reply Duke. At the moment I can't try because I have not bought it yet! Just looking into the issues and getting a bit puzzled by some of the advice I've found. In fact it is not a serious practical problem, as I will treat myself to a new set of cooking pans if necessary - and...
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