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    School Project : Weighted Timing Controller

    If this is a circuit simulation, does your simulator allow successful use of design practices that would otherwise be unacceptable in practice - such as a floating gate input?
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    School Project : Weighted Timing Controller

    What forces the input of U8 to be LOW when the DIP switch is opened?
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    Does low current and poor termination affect a transmission line?

    Do you see ringing or reflections? When connecting two lengths of coaxial cable for high frequency transmission one should use connectors with geometry designed to maintain the basic transmission impedance of the cable. Any discontinuities will result in signal reflections proportional to the...
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    Project Problems! Need guidance.

    It should be easy to drive a tank circuit with a sinusoid at the resonance frequency since the driving current will be zero. Of course, the current will be non-zero to initially energize the resonant tank, and to overcome any losses especially in a lower-Q tank. So why should a high-current...
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    Project Problems! Need guidance.

    Attached pdf analyzes the load current through the 22Ω resistor and parallel LC tank from DC to 100 KHz. Note that the power dissipation through the resistor at 60 KHZ is almost the same as at DC. As hevans1944 observed, due to the amplifier gain there would be a highly clipped waveform...
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    School Project : Weighted Timing Controller

    Instead of generating a half-rate clock for a 3-bit down-counter, just use a single SN74191 presettable 4-bit down counter as the timer to count down from max 15 and use the three most significant bits for the count display (with the least significant bit always set to 1). Or instead of forcing...
  7. L

    RC circuit

    Actually you did know that when you made the following statement; however, it was not apparent because of the numerical error by a factor of one-thousand. But 17 V/ms = 1 V per 59 µsec so 12 V takes 708 µsec. The time constant RC is 47K x 15E-9 = 705 µsec. If you eliminate the round-off...
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    RC circuit

    It is worth noting visually that the initial slope of an exponential charge curve will achieve the full value in just one time constant. Whereas the exponential curve takes about 5 time constants to reach full charge.
  9. L

    A bit of physics

    The correct answer depends upon which definition of 'ton' is being used.
  10. L

    A bit of physics

    In simple Physics we were taught that in the English system of units mass is measured in slugs. But it appears that the above calculation uses pounds as the unit of mass. Please explain.
  11. L

    A bit of physics

    Let's review the basics: Force = Mass∙Acceleration Work = Force∙Distance Power = Work/Time = Force∙Distance/Time = Force∙Velocity In this problem the power is constant, so as the velocity increases the force must decrease. And since the mass is constant the acceleration will decrease as the...
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    Calculating gain in this op amp stage

    Are you sure of those measured voltage values? With 8.8VDC at the input and 4.4VDC at the output the gain would seem to be 1/2; however, the DC gain is calculated as R116/R117 which is a little more than 2. So it would make more sense that the output is 8.8V when the input is 4.4V. And the...
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    A bit of physics

    Assume no aerodynamic drag or friction or electrical resistance, and no change in elevation. Calculate the kinetic energy of the car at 60mph. Then find how many 50kWsecs it would take to equal that kinetic energy.
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    Pros and Cons of analog and digital filters

    Digital filters require that the signal be digitized. There are limitations to how fast an analog-to-digital converter can be made to work. At some point in the RF spectrum no ADC will be able to convert fast enough.
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    School Project : Weighted Timing Controller

    In that case one promising approach would be a presettable binary down counter for the timer. However, it would count down one count at a time, not from odd digit to odd digit -- but the display would only show odd digits plus LED. One way to accomplish that is to design a custom binary to odd...
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    Pros and Cons of analog and digital filters

    You should also clarify whether you mean FIR or IIR digital filters. But in any case digital filters won't be much useful for high-frequency RF filtering, or for power line noise rejection. But for signal processing purposes the following link may have some useful information. The first...
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    School Project : Weighted Timing Controller

    I was considering your design approach with multiplexed ALU's and magnitude comparator and whether it might not be the most appropriate method. What if you took Harald Kapp's suggestion that the standard approach for period timing was a presettable down counter? But then the cycle time must...
  18. L

    School Project : Weighted Timing Controller

    Does this mean that if the requested cycle is greater than 15: ...a- the oven will fail to start? ...b- the oven cycle will start but stop at 15? ...c- the question is moot because the DIP switches will never be set for a cycle greater than 15?
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    N-type JFET LED CIRCUIT

    In the multisim model the N-channel JFET is the 2N3370. But the datasheet for the 2N3370 states the drain saturation current, IDSS, is just a fraction of one milliamp. Can you explain how transistor switching of that small current is able to drive the LEDs?
  20. L

    Downconverter Mixer Design

    The first thing I would do is an experiment to measure the carrier phase delay through wrist conduction. If the phase delay is significant enough, then the carrier oscillator signal may need to be phase shifted a similar amount before going into the mixer. If there is a significant...
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