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  1. L

    Low Pass Filter Problem

    R1 & R2 form a resistor divider so the question is whether the half-power point is measured from the DC baseline output, or from the initial input voltage. See the attached graph - you could find two different 3dB points.
  2. L

    Help needed to explain formula

    When the formula (Vripple = dv/dt x t) is used, the underlying assumption is that dv/dt is constant. With an RC discharge curve the initial slope, i.e. dv/dt, can generally be considered constant for the first third or so of the RC time constant. If the capacitor were to discharge at the same...
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    Using capacitors in bridge t-type

    My analysis of the circuit is in the attachment. The node equations are on the first line. These are manipulated into a transfer function of the form, 20log(Vout/Vin). For the graph, component values selected have Rp=Rl so for very low frequency or DC input, Vo/Vi=0.5 or 6dB. Very high input...
  4. L

    current division in circuit

    Your math is correct, subject to rounding errors. The placement of current meters within the circuit confirms that the current in a loop is the same everywhere in the loop. Where would you place volt meters in the circuit to confirm that the sum of voltage drops around a loop equals zero?
  5. L

    Capacitor & Inductor

    When you first apply voltage to a capacitor, the capacitor appears to be a short circuit. But as current flows the electrostatic field builds up intensity and then decreases to zero as the field intensity reaches maximum. When you first apply voltage to an inductor, the inductor appears to be...
  6. L

    Cueuing system help please!!

    Here is a block diagram of one possible implementation using SR latches and logic gates.
  7. L

    The Value of a Missing Resistor?

    How can you get 10V across R2 and also 10V across Rx?
  8. L

    Calculate Equivalent Capacitance

    You can never go wrong by writing the node equations, but first simplify the circuit by combining parallel capacitors. In the attached drawing I have added a voltage source (V) from which to calculate the current (I). This will be the constraint equation V/I=Zc that the input terminals to the...
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    LED Circuit Design Help

    How about interfacing to the speaker terminals with a small inexpensive audio transformer? A common one would be 10K:2K-CT where you would use 1K of the secondary coil across the speaker and feed the output from the 10K side into a Schottky rectifier. The 1K:10K ratio would give a voltage...
  10. L

    Linear Generator

    Take a look at the document "Design of a Linear Generator for Wave Energy Plant, January 2003" (2.1 MB). Skip over the mathematics and there is still a lot of good information on linear generators, especially diagrams for the mating of linear magnetic rotors and stator coils which aren't all...
  11. L

    Analog differential input - how to make it measure 0V when floating

    So you will pick the value of the shunt resistor not on the value of the thermocouple source resistance but rather based on the channel resistance of the analog switch.
  12. L

    Analog differential input - how to make it measure 0V when floating

    Since the source resistance of the thermocouple is likely very low (isn't it just two wires bonded together?), couldn't a 10K resistor directly across the PGA inputs with their 280K input impedance ensure a zero differential input when the TC is disconnected? I don't know what the resistance of...
  13. L

    find o/p voltage

    As shown in the attached diagram there are several ways to look at the circuit for analysis. I prefer the one where the diode offsets some of the Thevenin equivalent voltage from the input source, and the remainder goes through a two-thirds voltage divider to the output. If the diode had no...
  14. L

    CDMA

    The details of the code synchronization are implementation specific for any system design. But it is more than just using the same code. The receiver needs to maintain phase sync with the transmitted code to within a fraction of a microsecond for high spreading factors or else the correlation...
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    CDMA

    When you take a low frequency signal and multiply it by a high data rate pseudo-random code, what you get is a high data rate noise signal or a spread spectrum signal that can be transmitted over the air. At the receiver you can take the spread spectrum signal and multiply it by the same high...
  16. L

    Op Amp Slew Rate and Open Loop Frequency Response

    Think of a Bode plot of the open loop gain. Often simplified as a single number, the Gain-Bandwidth Product.
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    basic electronincs

    For What It's Worth: I did a Goggle search of "art of electronics pdf" which led to a filestube.com site offering the complete 2nd edition and from there to a hotfile.com site from which I downloaded a 52 MB pdf file which is a scanned copy of the 1989 published version (reprinted 1994). I'd...
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    follow-up questions of quadrature signal

    In order for the computer to produce the control voltage, it is presumed that a D-A conversion will be necessary. Then for your circuit to read this control voltage as a relative phase for digital lookup, it is presumed that an A-D conversion will be necessary. Why design the system in this...
  19. L

    quadrature singal

    Rats! I was fascinated by the prospect of low-noise sin with SinGal, and the magnitude of the forgiveness I would seek.
  20. L

    quadrature singal

    So the real problem is not quadrature generation but rather building a very stable voltage-controlled oscillator. From your answer I gather that the VCO signal is not sin(A*V*t) but instead sin(A*{K+V}*t)=20khz where K>>V.
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