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  1. L

    Pulse Width Modulation Signal Stretching Thingy?

    The application described requires a 50 Hz pulse stream where the pulse width must vary over a range of 1 millisec to 2 millisec. However there is a mystery source of a 33 nanosec pulse. Furthermore, this pulse must be stretched x180 to a width of almost 6 microsec to do anything useful with...
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    Why do crystal sets use diodes instead of transistors?

    http://www.arcsandsparks.com/aboutcrystalradios.html
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    Problem on amplifying signal ona differential OpAmp

    Yes, if the black wire is the GND of a dual power supply. No, otherwise. Recommended. No. It can be derived from a voltage divider using resistors. Note that the REF input load resistance is 40K so two 1K resistors as a voltage divider may not introduce too much loading error. How...
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    Need help with network theorems

    How would a private session on Skype make it informative and interesting for all the other readers of this thread in this forum?
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    Op-Amp Filter Circuit Transfer Function

    I derived the transfer function and found the corresponding form in a table of Laplace transforms. Not sure what you mean by splitting the numerator. I just substituted 1/s for Vi as the unit step function. Of course you realize this is only a theoretical exercise since an op amp circuit as...
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    diode

    The biasing determines at what point on the characteristic operating curve the diode will work. The result of reversal could be a change in polarity (for a rectifier circuit) to faulty operation of the circuit or possibly even self-destruction. However, if you also reversed the power supply...
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    New Member, need help

    It turns out that the trigonometric solution using phasor algebra is extremely simple because of the fact that: sin^2 + cos^2 =1. This confirms the book solution.
  8. L

    Counter 6-5-4-3-6-5-4-3... with D flips flops.

    Here is how to make a counter using D flip-flops: Identify some number of flip-flops to comprise the counter. Each FF will have a Q output and a D input. Construct a next-state truth table with Q0...QN as inputs and D0...DN as outputs. For any state of Q0...QN, D0...DN will represent the next...
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    New Member, need help

    Draw a phasor diagram of the given currents. There is the 19 A resistor current at zero phase angle; the 37.1 A motor current at some lagging phase angle (the cosine of this angle will be the power factor); and the total current of 53.6 A at some phase angle between the other two. The...
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    sensors and actuators?

    In the absence of any relevant design requirements or intended application information, I would suggest a pocket mirror as the "key" and a solar cell as the sensor. Mount the solar cell at one end of a plastic pipe at least ten cell diameters long. Use the "key" interposed between the sun and...
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    Elliptic (Cauer) Low pass filter design

    Are you saying that in theory the filter performance was perfect but in practice the filter you built and tested did not perform as well? What method did you use to tune the filter?
  12. L

    Connecting capacitor and Diode

    A capacitor/diode voltage multiplier circuit? See the application note: www.vishay.com/docs/88842/anusingr.pdf
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    sensors and actuators?

    Instead of a linear solenoid have you considered a battery powered gear motor driving a worm gear to achieve the linear displacement? How fast does the motion response need to be? Choosing a sensor might become self-evident once you describe what is it about the "key" that can be sensed.
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    LCR circuit calculations

    Again your results are close but accumulating round-off error. Also, need to check arithmetic for I2 & I3 phase angle. It seems setup is right but the result is different than what MathCAD gives. Attached is an extract from an instrumentation reference book explaining wattmeters. Note that...
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    LCR circuit calculations

    Attachment shows your Z values are close but beginning to accumulate round-off error. Next step is to calculate V from the voltage divider formed by Z1 & Z23, then with V find the current through Z2. Not sure what to assume about the wattmeter and power factor.
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    The calculus of FM super heterodyne receiver

    The problem here is that your math textbook has constructed an example of FM modulation with no identified modulation index. (Here the implied modulation index is 1.) So it provides no basis for examining the important details of FM modulation. Plotting the modulated carrier wave, while a...
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    Want circuit to return to previous state when turned back on

    To decide between a capacitor and a battery as the backup power source it would be necessary to know the maximum duration of the power interruption to design for.
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    Load resistance, dissipated power (AC)

    You got the same answer as myself. Does that make it correct? However, I calculated the load resistance a different way from the loop voltage equation for the inner loop using the reflected load resistance and source voltage of 600 volts at 20 amps. 600 = 20x(0.6+5^2xRload) ..... Rload =...
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    how does a PULSE code MODULATION WORKS?

    Is the IR transmitter/receiver designed for PCM transmission? Otherwise, how will you handle clock generation, clock recovery, and signal framing?
  20. L

    Load resistance, dissipated power (AC)

    If your textbook doesn't cover how to do that, then we should not do it here. So consider another approach. As before, the total power is the power dissipated in the wire plus the power dissipated in the load. But you already know the current through the wires and the current through the...
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