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  1. KrisBlueNZ

    5U4 Rectifier tube

    LOL In another thread, I asked the OP what his AC mains voltage was... and it was stated in his first post, and in the thread subject!
  2. KrisBlueNZ

    5U4 Rectifier tube

    Yes, true. Yes, I suggested that earlier in the thread (post #6). Actually I suggested switching the rectifier's filament supply, but your suggestion is probably better.
  3. KrisBlueNZ

    Multiplexing project

    You still haven't explained anything about your project! WHAT IS THE PURPOSE OF THE PROJECT?
  4. KrisBlueNZ

    5U4 Rectifier tube

    Good idea Chris. I suspect you would need several zeners in series anyway, to handle the required power dissipation.
  5. KrisBlueNZ

    Multiplexing project

    Is this for a matrix display using magnetised discs that are black on one side and white on the other side? Whatever you're doing, I suggest that you describe your whole project. Steve asked you in post #10 of this thread and you avoided the question. We're now up to post #17 on the thread and...
  6. KrisBlueNZ

    Change DVD player from ac to 12v dc

    Where did you read that? Can you give links? It's definitely not true in your case. That power supply will work nicely at 160VDC. Not very hot. If there's no ventilation it could get quite warm. If you can get an inverter that will convert automotive 12VDC to 120VAC at 15 watts for only $20, I...
  7. KrisBlueNZ

    Watchdog Timer

    The two minute timeout will relate to user input. If the user doesn't enter their PIN or select a transaction, the firmware will time out. This timeout on user action has nothing to do with the watchdog timer. The watchdog timer will typically be set to a much shorter timeout, normally less than...
  8. KrisBlueNZ

    Change DVD player from ac to 12v dc

    Yes, you would ideally want 170VDC. That's just a nominal value and the power supply will work with somewhat less, but not a lot less. I was hoping the player would be a universal input one that has a minimum input voltage of 85VAC, which would be only 120VDC. In either case, I think it may be...
  9. KrisBlueNZ

    Newb needs help with a 2 second delay for milsim

    OK, take a look at this circuit diagram (schematic) and voltage and current graphs. This is probably the simplest solution. Q1 is an N-channel MOSFET. It works like an electronically controlled switch. When the voltage between its gate terminal (the left hand connection) and the source...
  10. KrisBlueNZ

    5U4 Rectifier tube

    You need to make sure that once the thermistor has warmed up, the filament voltage is not significantly lower than it should be. In other words, make sure that the thermistor isn't dropping much voltage. That is why it's very important to get the right thermistor. Actually I suspect that a...
  11. KrisBlueNZ

    Change DVD player from ac to 12v dc

    You don't need a sinewave inverter. You don't even need an inverter. A power supply like that will run from DC just fine; you just need enough voltage. That power supply has a very simple AC mains input stage. It just rectifies the AC and smoothes it. Look at the player's back panel for the...
  12. KrisBlueNZ

    Change DVD player from ac to 12v dc

    It's great (and unusual here) to see such a detailed and complete first post, with voltages marked, even! This is definitely possible, but not simple. I have little experience with automotive audio. Others on this forum probably have more. Also you should do some Googling for some of the...
  13. KrisBlueNZ

    5U4 Rectifier tube

    Putting a thermistor in the rectifier filament supply may be workable if you can find a suitable component. I don't think it would damage the rectifier, but make sure the filament voltage is not much lower than it should be when the thermistor has warmed up fully. Some guitar amps handle this...
  14. KrisBlueNZ

    Help Finalizing LED Boost converter

    All good advice from Harald here. I would just add that I'd use a Schottky diode rated for at least 20V to be safe, and connect a zener of say 18V across the LED string, because the LED string, being off-board, could get disconnected or broken, and that would expose the diode to a very high...
  15. KrisBlueNZ

    heat sink compound

    I think Steve recommends chocolate... :p
  16. KrisBlueNZ

    Programming of MUC

    I assigned -1 (equal to 0xFFFF for a 16-bit integer) initially so that the first time update_lcd_from_port_status() is called, it will unconditionally update the LCD. This is guaranteed because the actual port status is 0 or 1 (FALSE or TRUE), and the first time the function is called, this will...
  17. KrisBlueNZ

    Need help diagnosing H-Bridge

    Thanks for the clarifications. I'm afraid I don't think I'll be able to help. I know nothing about force feedback steering wheels. I recommend Steve's advice. Good luck!
  18. KrisBlueNZ

    Need help diagnosing H-Bridge

    What's a "computer FFB steering wheel"? What's a "540" Schottky? Do you mean an MBRS540 or something? What's the model number? Do you have a link to user documentation, service manual, or schematics?
  19. KrisBlueNZ

    Class D "trouble" shooting

    If you think the noise is 800 Hz it won't be the switching frequency of the power supply! Switching supplies run at 20 kHz and higher. You really need to find out more about the noise - the frequency and waveshape could be helpful to know, and check the power supply rails to see if it's coming...
  20. KrisBlueNZ

    Battery powered Current sink with low voltage cutoff

    U2 regulates the +8V reference voltage. The 33k/15k voltage divider feeding U2 pin 1 sets the voltage (see the TL431 data sheet). The other resistors set the voltages at both ends of the two potentiometers (VRT and VRC). VRT needs 8V at the top end and 4V at the bottom end, to set the...
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