Search results

  1. L

    Thevenins and nortons circuit help

    Looking for the total current flowing through a bridge. Attached image shows the node equations for the two bridge voltages. Total current into the bridge is Ii=(1-Vab)/Ra+(1-Vcd)/Rc where Vi has been arbitrarily set to 1 for convenience. Equivalent resistance is Req=Vi/Ii.
  2. L

    Thevenins and nortons circuit help

    I was looking at finding the equivalent resistance of the original circuit and noticed the configuration is an unbalanced bridge. There is no easy way to calculate an unbalanced bridge by combining resistance in series and parallel. One needs to write the node equations, find the two bridge...
  3. L

    Thevenins and nortons circuit help

    Took your circuit for finding the equivalent resistance and redrew it. Is that what you used for finding Rth?
  4. L

    Thevenins and nortons circuit help

    Ohm's Law relates 3 items: voltage, current, resistance. Given any two the third can be calculated. Equivalent linear circuits have 3 items: Thevenin voltage, Norton current, Equivalent resistance. Ohm's Law applies here. Does R5 have a value?
  5. L

    Bandpass filter help

    First, you do realize that the bass & treble labels in the circuit are interchanged? As for the two capacitors and two resistors, the 2.2 uF is for AC coupling to block the DC bias point of the op-amp, while the 39K resistor is to set the DC bias point of the capacitor. The diode rectifies the...
  6. L

    Bandpass filter help

    Tried to get a Bode plot of the three bandpass filters in the referenced circuit. Assumed that the amplitude control is at the midpoint, giving 6K in parallel with 680Ω as the input resistance.
  7. L

    Smooth Acceleration circuit

    Sounds like you could put the capacitor on a sticky switch. At some threshold on the RC charge curve the capacitor will be switched out of the circuit and quickly discharged. When the throttle has been returned to the idle position the capacitor will be connected again to delay the next...
  8. L

    Shadow signal

    If you are generating the triangular wave from the first pulse, could you not then generate the shadow triangle from the shadow pulse in the same way?
  9. L

    Obtain transfer function using KVL

    Let's forget about your particular homework problem and consider instead the general problem of a cascade voltage divider. As shown in the circuit below, each of the 'Z' boxes can represent either a simple resistance, an imaginary reactance, or a complex impedance. The first method of solution...
  10. L

    Obtain transfer function using KVL

    I am experiencing difficulty with recognizing what paradigm you have used to write the circuit equations. However, it is a certainty that the transfer function will be some combination of R, L, C & s. Nothing else. The transfer function given above has a V.
  11. L

    NPN BJT Transistor Biasing problem

    Can't remember ever seeing a stipulation that an amplifier circuit use "only DC voltage for it's operation." So is this merely stating the obvious, or does it mean something special? Is the amplifier meant to be DC-coupled? Will the input signal be uni-polar?
  12. L

    Curiosity: NPN Opto Coupler with no base

    Use the characteristic curves for the transistor and draw the load line. Vce=5 when Ic=0. For Rc+Re=2K, Ic=2.5mA when Vce=0. That is the top load line (in blue) on the diagram. For Rc+Re=20K, Ic=0.25mA when Vce=0. That is the bottom load line (in blue) on the diagram. Because If<5mA the...
  13. L

    Obtain transfer function using KVL

    First recommendation: drop the (s) notation; the extra (s)'s will be confusing. The transfer function is Vout/Vin so you want to find V0/V1. Using KVL is problematic because the first step in using KVL is to designate loop currents and solve for those. But that does not get you V0 easily. If...
  14. L

    FET- trouble with finding Id

    No. Just that Vp is one particular value of Vgs so the ratio must be positive. The whole equation doesn't make any sense otherwise (in the region of interest).
  15. L

    FET- trouble with finding Id

    Have you defined polarities such that the term Vgs/Vp is always a positive number?
  16. L

    Reducing gates using k-maps?

    Z is shown as the sum of 3 terms when it should be less than 3 terms. That should be obvious from the K-map. How is it that you know the circuit can be reduced further? Has someone else already solved this problem?
  17. L

    My socratic homework

    Consider Socrates' dialog with Meno's slave boy (http://classics.mit.edu/Plato/meno.html) about the geometric method for doubling the square. Socrates questions the slave in a very leading manner, essentially providing the answer to every question. Is this the sort of technical questioning...
  18. L

    My socratic homework

    "No answers will be given, only guidance." I don't believe that I provided an answer to the assignment. What I provided was an illustration of a method that would begin to provide the answer. There was still much work that needed doing in order to get the answer. Or has this homework forum...
  19. L

    help me quickly: diode curves question

    If the curve is to be treated as "piecewise linear" then for each piece of the curve the diode can be replaced by a resistor and a voltage source. But how does one know which piece of the curve to actually use? All I can imagine is to make an assumption on where to start, find the dynamic...
  20. L

    FFTW???

    Given N real-valued input points, the DFT provides ½N meaningful output points. Would a real-valued FFT algorithm take advantage of this to improve computational efficiency? So I searched the term "real-valued fast Fourier transform algorithm" and returned some interesting results. Among them...
Top