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Type: Posts; User: barry

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  1. Replies
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    Closed: Re: Coaxial cable capacitance

    If you've got a 75 ohm termination, you're only going to be able to pull to VDD/2.
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    Closed: Re: Tracking Phase comparator Logic

    This makes zero sense. By your definition, if the phase difference is 5us, your output is 5. If it changes to 10uS you "add with its past input", so now your output is 15?

    People keep asking you...
  3. Closed: Re: Stability issue of the closed loop feedback in fully differential ampliifer

    No one suggested using a small resistor, but 100M is almost no resistor at all. I suggested trying a smaller resistor (1M, 100K). Did you do that?
  4. Closed: Re: How hold violation caused by below mentioned Scenceio

    How about a diagram? Your description is very confusing.
  5. Closed: Re: Stability issue of the closed loop feedback in fully differential ampliifer

    Maybe those feedback resistors are too high. Combined with the parasitic capacitance you might have built an oscillator. Or perhaps a problem with input bias current. Just try smaller resistors and...
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    Closed: Re: PCB for testing a SAR ADC?

    Since you're the only one on this forum who knows ANYTHING about your ADC only you can tell what you need to connect to it.

    I am just astounded that you designed the chip, but dont know how to...
  7. Closed: Re: Beginner question about a micro-controller project

    Totally agree with Klaus. How can you build something without knowing its requirements first?

    And you seem to be letting the devices drive your requirements, rather than the other way around. You...
  8. Closed: Re: Beginner question about a micro-controller project

    Any of the micros you mention should be able to perform the tasks you require. If you're familiar with AVR, I would definitely pursue that path first.
    Do you need to design the hardware, or just...
  9. Closed: Re: how to determine the resistance of a running circuit

    Your original post said you don't want to 'ruin the circuit'. How do you propose measuring the current without breaking a path an inserting an instrument (e.g., meter)??
  10. Closed: Re: how to determine the resistance of a running circuit

    If you put a small resistor in series with the device, you can measure the voltage across it to get current, then measuring the voltage across the device you can calculate the resistance.
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    Closed: Re: Old Altera FPGA EPM7128

    Is this for productioin, or just something you want to play with? If it's just to play with, what do you have to lose by spending a few dollars (or Euros, or whatever)?
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    Closed: Re: Implementation of sine cosine using LUT

    You’ll have to read the Matlab documentation.But, if I had to guess, I would assume they simplify take two adjacent points from the LUT and interpolate between them.
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    Closed: Re: Implementation of sine cosine using LUT

    CORDIC is an algorithm for performing calculations. A LUT is simply that, a look-up table: phase in, amplitude out. The CORDIC implementation takes several cycles to produce an output; a LUT produces...
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    Closed: Re: How to achieve Vref changing with Vdd

    This STILL doesn’t make a lot of sense. If you’ve got a system which has a sensitivity to a certain parameter, in this case Vdd, you can either make Vdd more stable, or make your system less...
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    Closed: Re: How to achieve Vref changing with Vdd

    This makes no sense. First you say you want to compare Vref with Vdd. Then you say you want Vref to CHANGE with Vdd. THEN you say a constant voltage is supposed to connect between the two voltages. ...
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    Closed: Re: Design a system clock monitor in verilog

    Wait, you want to monitor a clock with ITSELF? Either I don't understand your question, or you're on a fool's errand. Maybe you need to restate what you are intending to do.
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    Closed: Re: Difference circuit not acting as expected

    You don’t really give us a lot of information. Like WHAT your opamp is—Don’t you think that’s an important bit of information? And Power supplies? And you know that ECL needs to be terminated, right?...
  18. Closed: Re: How can I measure AC current with ~500 kHz frequency?

    A multimeter is not going to work at 500khz. I think you want to look at a current transformer. Without further information, it’s difficult to make a suggestion. Is this for occasional measurement?...
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    [SOLVED]Closed: Re: Ground plane in audio amplifier?

    The amplifier is obviously unstable. But is it because of the plane? Perhaps the additional capacitance of the plane is the problem. You need to analyze the circuit a little more closely, considering...
  20. [SOLVED]Closed: Re: How to generate a sine waveform using a STM32 Nucleo-64?

    You can also generate a sinewave with a lookup table and counter (DDS). You don't have to use rational functions. But that 1MHz DAC will be a problem...
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    Closed: Re: vhdl problem debug help please

    I, for one, never use separate clocked/combinational process for state machines. I know all the literature says this is the way to do it, but I find it's always a problem (just like what you're...
  22. [SOLVED]Closed: Re: How to generate a sine waveform using a STM32 Nucleo-64?

    You're going to have a pretty rough sinewave since the maximum sampling frequency you can have is 48MHz. (Not even sure if the onboard DAC can run at the frequency).
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    Closed: Re: vhdl problem debug help please

    You need to have "count<=count+"01" in a clocked process, not a combinational process.

    And have you included ieee.numeric_std? Have you observed the value of "count"? Is it incrementing? Probably...
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    Closed: Re: Logic duplication and optimization

    I disagree. If there is ANY optimization, your intermediate sum, "a+b", is going to be optimized away. If you keep that intermediate sum for the sole purpose of seeing it in Chipscope, you're not...
  25. Closed: Re: Properties of material ( silver and copper )

    ALL the properties? Maybe you could narrow it down a bit; like electrical properties or mechanical or chemical properties or crystal structure or thermal properties or...

    Or, better yet, try this:...
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