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  1. L

    Controlling the voltage into heating element

    One solution is to use a TRIAC with the micro-controller in the trigger circuit. Think of a lamp dimmer with a 1500 watt bulb. Of course, that will put a lot of noise on the AC power line.
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    Load resistance, dissipated power (AC)

    Internal resistance might be considered similar to wire resistance when the internal portion of a device comprises wire; however, when internal resistance is due to leakage factors it would be modeled as a parallel resistance rather than being in series with other elements of the model. It...
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    DC Motor Stall Current and Power Supply Questions

    Have you thought of using a switched current limiter? Since the machine loading is expected to be much less than the available motor torque, the only time that the power supply will be asked to supply the full stall current is for a fraction of a second during startup. So add a resistor to the...
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    Load resistance, dissipated power (AC)

    Because these are ideal transformers, given the value of current in one loop you know the value of current in all loops. Look at the middle loop -- What is the value of the voltage source on the other side of the transformer? What is the value of the load resistance reflected back through the...
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    advance diode question

    With the above perspective this becomes exceedingly simple. Identify the point where diode conduction begins - in all cases this is when the voltage across the diode equals zero, i.e., VRx=Vx where x is A, B, C, or D. You merely need to determine the region of conduction, when VRx is (more...
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    advance diode question

    Are these ideal diodes, or must there be a forward voltage drop (0.7 volt?) before they are considered to be conducting? Is the external applied voltage (+,-) the same for each case? For starters I would zero out the battery voltage and analyze whether the applied voltage (+,-) would cause the...
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    Mesh-current method in circuit analysis

    I get your same values for Ia, Ib, and Ic. Looking at the polarity of the voltage across the current sources, it appears they both dissipate power just like resistors. However, review how you calculated the P.0,67 value of 384 W since all I got was 4 V at 12 A.
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    Help design analog multiplier to use as AM modulator

    If you are limited to the op-amp as your only active element, then the attached technical paper (first 2 pages) may be of interest. It shows how to make an analog multiplier using only op-amps.
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    Help design analog multiplier to use as AM modulator

    Try googling "Gilbert cell amplitude modulator". It might give you some ideas.
  10. L

    ok this is sci fi right here

    A capacitor is a dielectric between two conductive plates. Follow the spiral radially outward from one black line to the next black line where the pattern then repeats itself. Between the black lines there are four layers of dielectric film. Four dielectrics = four capacitors.
  11. L

    ok this is sci fi right here

    So your tubular capacitor will have 4 capacitors connected in a series ring?
  12. L

    ok this is sci fi right here

    Yes, excess electrons accumulate within the conductive portion but they are evenly distributed when the electromagnetic fields are static, as in this case; they do not bunch to one side of the plate.
  13. L

    ok this is sci fi right here

    In the presence of an electrostatic field, electrons will migrate to one surface of a dielectric material (molecular dipoles will rotate); that is how a capacitor works. But what if instead of a dielectric material there is nothing but vacuum? There are no dielectric electrons to bunch...
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    ok this is sci fi right here

    Have tried to make an equivalent circuit of the configuration as presented. However, it was uncertain just how to model a copper plate since a copper plate is indistinguishable from a copper wire. Also, the specks shown as bunched to one side of a plate, which I assume are meant to be...
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    Red and green LEDs

    When everything is in parallel you can treat each LED as though it is the only thing connected to the power supply. So do the calculation for the current limiting resistor individually for each diode, then connect each resistor/LED combination in parallel. Of course, if the heavy current drain...
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    Mixer circuit pre-amp

    I don't quite understand the specification as given: "-Level gain (Av dB): 42 dBu". Now 42 dB is a voltage gain of about 126 but dBu gives a signal level referenced to 0.7746 volts (1 mW @ 600 ohms) so 42 dBu is 97 VRMS or 274 volts P-P. Are you really expected to design a circuit for a 274...
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    Calculus I homework question about rate of change of resistance in an RC circuit

    As was stated previously the problem is to find the derivative dR/dT{(R1xR2)/(R1+R2)} and substitute the given values to get the answer. There is a numerical method to check for the correct answer. One millisecond prior to the point of interest R1=79.9997 & R2=99.9998 while one millisecond...
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    Calculate Current, Power, EMS..

    If you would like to use standard methods, then first choose the most reasonable ground point, i.e. node 'C'. There is no need to complicate the problem by converting circuit components (R) into equivalent conductance (G). Every complication is a new opportunity to make a conceptual or...
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    Calculate Current, Power, EMS..

    A phantom reference is a sop for anyone who absolutely believes that a reference node is necessary in order to create the node equations. However, I have demonstrated that no reference node is required because every term in the node equation has the voltage difference between that node and...
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    Calculate Current, Power, EMS..

    What if the reference node is not the lower right corner? Suppose there is no reference node, or just a phantom reference? That would not invalidate the equations as written, but setting Vc=0 makes it easier to get a solution.
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