Search results

  1. L

    Logic Circuit help

    It is not correct. Specifically, the Boolean functions do not match the gate types. (e.g., "+" is not AND)
  2. L

    Logic Circuit help

    Looks good to me. I like to use index numbers for the truth table, and mark as much information as possible on the truth table. See attached image. On my K-maps I also put little index numbers in the corners of the boxes. That makes it easier to transfer the contents of the truth table onto the...
  3. L

    Logic Circuit help

    The number is odd only and always when the "1" input is HI, A= 1. The number is even when either the "2" or "4" or both inputs are HI and the "1" input is LO. So the green LED is identical to input A. The red LED is HI when either B "2" OR C "4" are HI, AND A "1" is NOT HI. That is how you get 3...
  4. L

    Assignment problems

    What is the extent of the assignment? So far, I get the pill detector and the pill counter. But, "an automatic counting and bottling tablet system" would necessarily include a pill transport and dropping mechanism, and some sort of bottle transport/conveyor. Are you required to design the...
  5. L

    need help on clock D flip flops table

    Whatever happens will be determined by whether the flip-flop is triggered by the rising or falling edge of the clock. When the flip-flop is triggered by the clock the 'D' input is latched into the 'Q' output. A 'reset' input, if any, is usually asynchronous & independent of the clock. So is the...
  6. L

    Superposition on circuits with impedance elements

    Rather than memorize a formula for current division, one could employ a method where the general format for voltage division and for current division is identical. Voltage division is proportional to resistance {impedance} Ω, whereas current division is proportional to conductance {admittance}...
  7. L

    Common Base

    Drawing the load line does not involve 2 voltages & 2 resistors. The load line is all about the load resistor, and finding two points of corresponding load current and load voltage in order to draw a straight line between those two points which will then be the load line. So think in terms of...
  8. L

    Determine the unknown voltage in an ideal Op-Amp circuit

    Whenever an op-amp circuit operation is not intuitively obvious (quite often, for me) and writing the gain equation is not a clear path, it is best to write the node equations for the circuit. In this case a single node equation for the '-' input to the op-amp consisting of 3 terms because the...
  9. L

    Question about B-E voltage.

    You might find the answer you seek at the following webpage: http://www.electronics-tutorials.ws/amplifier/transistor-biasing.html As I said before, engineers tend to make a lot of simplifications and take a lot of shortcuts. Such name dropper you are! No problem. I mean, how many 'Barrie...
  10. L

    Question about B-E voltage.

    Emitter degeneration is absolutely necessary to reduce the circuit's sensitivity to variations in transistor beta. When a constant value is assumed in the design, and negative feedback handles the rest, that equates to no role. One must be pretty desperate to have dragged in obscure non-linear...
  11. L

    Question about B-E voltage.

    I understand the basis for your opinion, but I disagree. I have a different opinion, as stated. The words in your description do not coalesce into any meaningful circuit model. Since the problem is obviously not on this end, you need to provide a diagram identifying all entities involved and...
  12. L

    Question about B-E voltage.

    It is what it is. Current flows, charge moves. That statement is nonsense. How many voltages are there across the terminals of a coil? A superconducting coil is nothing more than an ideal inductor. The inductor voltage is L∙di/dt. If the inductor voltage is zero, then the current flowing in...
  13. L

    Question about B-E voltage.

    Current flows, charge moves. So is the correct answer to @(*steve*) 's question about coils YES or NO? What if only half the energy stored in the magnetic field is bled off and the coil shorted again? What happens to the remaining energy? Does a lesser amount of current then keep flowing in...
  14. L

    Question about B-E voltage.

    Of course not. That would be a fool's errand simply because Vbe has no role in transistor circuit analysis & design other than as being one constant diode voltage drop. The exact value assumed by Vbe is a concept from device physics that has no role in discrete transistor circuit analysis...
  15. L

    Question about B-E voltage.

    Yes, if it is a pure inductor (no resistance). Short out a super-conducting coil that has current already flowing and the current will keep circulating forever (with no voltage across the coil).
  16. L

    Question about B-E voltage.

    Engineers tend to make a lot of simplifications, and take a lot of shortcuts.
  17. L

    Question about B-E voltage.

    But your post itself explains why Vbe is irrelevant - it is only the derivative of Vbe that gives useful information for small-signal analysis. Also, in reality the transconductance value is obtained by other means than differentiating the Ic vs Vbe curve. Where Vbe is sometimes useful is in...
  18. L

    Question about B-E voltage.

    The part I don't understand is how Vbe controls Ic when circuit analysis technique is to assume Vbe is a constant voltage around 0.7 volts. In reality there is a highly non-linear temperature-dependent relationship between Vbe and Ic that can best be summarized as "Vbe is a constant voltage...
  19. L

    Temperature and Thermometers

    This image contains all the data necessary to answer the question. Try plotting temperatures in K, C, & F on a vertical scale against a horizontal scale of absolute temperature (i.e., the lowest possible temperature is zero). Note where the plotted lines may intersect.
  20. L

    7-segment display 3-to-8 decoder logic circuit (please help, thank you)

    Quite true; because "creating" this sequence would be a different problem.
Top