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  1. R

    NPN transistor still working? Strange ..

    You are forward biasing the LED diode and the base-collector diode. That leaves 10 volts or so to reverse bias the emitter-base diode. Is the e-b diode capable of holding up to that much reverse voltage? Or, did the voltage blow through and short it out. I would check the transistor to see if...
  2. R

    Please help me through diff equation questions

    Here is the solution using an integrating factor. You can't fool Mother Math, the solution will be the same. Ratch
  3. R

    Please help me through diff equation questions

    You are going to have to learn how to do this, or you won't get very far in DE. Ratch
  4. R

    Please help me through diff equation questions

    The unit step function u(t) is 0 when t < 0 and 1 when t > 0 . Therefore, if x(t) = u(t), 2 x(t) = 2 when t > 0 and 0 when t< 0. So you have to solve the DE twice for each range of t. Ratch
  5. R

    Please help me through diff equation questions

    OK, x(t) = u(t) , which is the unit step function. For t > 0, you have to solve the DE dy/dt + 2y(t) = 2 with the given condition. For t < 0, you have to solve the DE dy/dt + 2y(t) = 0 with the given condition. Looks like the separation of variables method will work. Ask if you have any more...
  6. R

    Question about Diode potential of anode with respect to cathode

    You have to have an infinitesimal amount of voltage across an ideal diode for current to be present. Even a copper wire short will not have any current existing at zero volts. Ratch
  7. R

    Ohms law chart from radioshack.. vs ..home made ohms chart

    All those formulations are variations of the definition of resistance. See the thread below for a discussion about this. Too bad the thread changes to a discourse about something else, but if you read from post #4, you will get the jist of what I mean. Basically, Ohm's law is about resistive...
  8. R

    A question about electrical Theory

    Power is determined by voltage, current, and phase between the two. If you know those three parameters, the power can be determined regardless of the load. Your question does not make sense. If the power changes in a circuit, there will always be a reason. If one or more of the three named...
  9. R

    Woo-Woo Charging...food for thought

    If you do "charge" your battery, what do you charge it with? In other words, what substance do you put into your battery to "charge" it? Ratch
  10. R

    Spring constant versus electric repulsion

    He should write 1/C^2 to avoid confusion and bemusement. Ratch
  11. R

    Particles in a Field

    Do you mean use the milli-second abbreviation ms for meter-sec? No way, I am sticking to standard notation. Ratch
  12. R

    Particles in a Field

    The speed of light does not accelerate. How can you compare any acceleration to the speed of light? Ratch
  13. R

    Particles in a Field

    No, a newton is kg-meter/sec^2 Ratch
  14. R

    Particles in a Field

    Are you comparing acceleration to velocity? What is the acceleration of light? Ratch
  15. R

    Particles in a Field

    chopnhack, What is all this scratching around for? The initial starting velocity was given, the final arrival velocity is zero. The time to return is the same as the time to get there, so just multiply your arrival time by two to get the total time. Ratch
  16. R

    Particles in a Field

    What's the hangup? The force on the proton can be calculated by its charge and the electric field strength. You know the mass of the proton and the force on it so the deceleration can be calculated. From the deceleration you can calculate the time when the velocity will be zero. The same...
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    Interesting Ad

    To the Ineffable All, I thought that everyone would be interested in an ad that appeared in Electronic Design, September 27, 1973, pg. 27. That is none other that Bob A. Pease, the engineer who liked beards and hated seat belts. Compare with https://en.wikipedia.org/wiki/Bob_Pease, RIP...
  18. R

    Calculate Op Amp Gain

    No, the gain is 1+R2/R3 . See post #11 Ratch
  19. R

    Calculate Op Amp Gain

    The above equation simplifies to A = (R2+R3)/R3 as I calculated in post #11. R1 cancels out. I believe he meant no influence on the gain at vout. Ratch
  20. R

    Calculate Op Amp Gain

    It must be stipulated that the values of the output and U1 will be 2 v and 3 v respectively only if Vin = 1 v and R1=R2=R3. Ratch
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