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  1. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    You never leave inputs floating. The digit select pins are outputs, and you don't need them, so leave them unconnected, but Latch Enable (10) needs to be tied low and Clock Disable (11) needs to be tied low as well. Also pin 4 needs to be tied either low or high (doesn't matter which) and pin 3...
  2. KrisBlueNZ

    Whats a K00AF ?

    Are you sure both of those statements are true? You seem to be saying that (a) the 19V supply is not present (at some point in the power supply section, I guess) unless the "lid board" is disconnected, and (b) the laptop doesn't power up at all, regardless of whether the "lid board" is connected...
  3. KrisBlueNZ

    Can I return to a return?

    It also reduces code size and execution time. I always place a comment "Fall through..." when one subroutine falls through to the start of another one. Why do you say it's "the stuff of nightmares"?
  4. KrisBlueNZ

    Can I return to a return?

    I can't follow your program at all, but in general, it's perfectly valid to return to a return instruction. For example: 01. main: 02. . . // do stuff 03. . . call subroutine1 04. . . jmp main 05. 06. subroutine1: 07. . . // do stuff 08. . . call subroutine2 09. . . ret 10. 11. subroutine2: 12...
  5. KrisBlueNZ

    Help: Driving a 5 inches 7 segment display

    I think you need to re-read post #1 on this thread!
  6. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    I agree with runem; the MC14553 is not the best choice for this application. The minutes counter should be clocked from bit 2 of the tens of seconds counter. These counters are all clocked on the falling edge of their clock inputs. When the tens of seconds reaches 4 (0100), the clock to the...
  7. KrisBlueNZ

    Bottleneck 555's 0.2A Stuck project

    The diagram in post #23 is right, apart from the marking that shows the currents into the 555. Pin 4 draws no current at all when it's tied high like that, and pin 8 draws less than 200 mA. I would use a label of "<20mA" for the current flow to pin 8.
  8. KrisBlueNZ

    Non invasively monitor AC backup generator power.

    The sound card has two inputs - left and right. Yes, you would have to write some code. I'm not saying it's the best solution, but I think it could be made to work.
  9. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    When the ones digit counts above 9, it internally resets to 0. It's a BCD counter. That action also increments the tens digit, but you will only be using one digit per MC14553. No, I'm referring to the text description on page 5, which says "The Master Reset input, when taken high, initializes...
  10. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    The MC14553 has a multiplexed output. There are four output pins. The chip multiplexes the outputs in three phases. First it feeds the value from the ones digit counter (actually, from the ones digit latch) to the output pins and asserts the first display select, then the second, then the third...
  11. KrisBlueNZ

    Help: Driving a 5 inches 7 segment display

    Multiplexing operates at hundreds of hertz. You can't have relays operating at those frequencies.
  12. KrisBlueNZ

    Non invasively monitor AC backup generator power.

    You won't be using the sound card input when you make announcements...
  13. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    A 555 will oscillate at 100 Hz but it's not accurate. Yes, I meant tens of seconds. To make a counter count from 0 to 5 you need to reset it immediately when it reaches 6. You do this with an AND gate as I described. You don't "make it stop counting" at 0101. Yes, you need to reset all the...
  14. KrisBlueNZ

    Help: Driving a 5 inches 7 segment display

    Relays are no good if the displays are multiplexed. Also they're expensive and large.
  15. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    Maybe. You may be able to use one MC14553 for the rightmost three digits (hundredths of seconds, tenths of seconds, and seconds), but you'll need to use two more for the tens of seconds and the minutes digits. This is because you need full-time access to the outputs of the tens of seconds...
  16. KrisBlueNZ

    5 Digit Digital stop watch using a MC14553b and TIL 311

    It looks like you may be able to use five separate MC14553s. You will have to disable the multiplex oscillators (tie pin 4 either high or low) and ensure that the devices all receive a pulse on MR on startup so they all present the ones digit on their outputs. You will need gating on the...
  17. KrisBlueNZ

    Low Voltage protection (cut at 33v - Full charged 44v)

    Ah, yes, I see. I think you're right.
  18. KrisBlueNZ

    RGB LED Color Slider

    Building an instructable doesn't demonstrate that you have any knowledge of the subject. Have you asked your tutor whether that would be allowed? What have you been learning about? Have you learnt about any particular ICs? If so, you should do a project using those ICs, obviously.
  19. KrisBlueNZ

    Non invasively monitor AC backup generator power.

    The voltage-output version will generate a signal representing the load current, which could be acquired by the sound card. It already has the right plug to connect to the line input. You might want to add a couple of diodes across the wires (e.g. two 1N4001 diodes, both connected across the two...
  20. KrisBlueNZ

    Whats a K00AF ?

    Just a crazy idea, but is it possible that this "lid board" detects when the "lid" (display) is closed? In that case it might be a hall effect sensor that's activated by a magnet in the lid. What is the fault on the laptop? What effect does disconnecting that board have on its behaviour?
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