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  1. KrisBlueNZ

    Installing Cabinet LEDs in my Workvan

    I thought that varistor would be suitable. The minimum voltage is just the lowest voltage where it will start to clamp. It doesn't mean that it needs at least that much voltage! As long as its maximum clamping voltage is less than the maximum allowable input voltage of the regulator, it will do...
  2. KrisBlueNZ

    Power Regulation Strategy

    I guess not, as long as your TVS is rated higher than the expected peak voltage, and the diodes are rated comforably higher than the TVS's maximum clamping voltage. If that means you have to use Schottky diodes rated at 80V or 100V, the VF improvement isn't so dramatic, although the cost...
  3. KrisBlueNZ

    IR LED off of 24V rail - Best way to do it?

    That looks reasonable. If the 24V rail is fairly constant, and efficiency isn't a concern, I would probably just use a big series resistor and let it get hot. You can get fully assembled buck regulators on eBay for under $2. Search on eBay for LM2596. If you get an adjustable one, you can use a...
  4. KrisBlueNZ

    Power Regulation Strategy

    No, I wouldn't recommend that. Schottky diodes are too easily damaged by very brief overvoltage. Unless your incoming mains supply has aggressive filtering and suppression, I think that would be risky. No, I haven't had problems with input smoothing capacitors overheating. I agree that two...
  5. KrisBlueNZ

    Power Regulation Strategy

    I find Digi-Key have a lot more information in their product selector - i.e. more columns, which makes it easier to filter out the unsuitable parts. They're not perfect, and sometimes I wish they had a column for an important characteristic because I could eliminate a lot of possibilities based...
  6. KrisBlueNZ

    Power Regulation Strategy

    No. Any fast edge has higher-frequency components. The steeper the edge, the more high-frequency components it contains. Do you know about Fourier analysis? You know that a sinewave contains only the fundamental frequency, but a square wave contains the fundamental plus a series of harmonics...
  7. KrisBlueNZ

    help with voltage divider

    Yeah I had a chuckle too. But then, I have a sick mind.
  8. KrisBlueNZ

    Assembling splitted integer C

    If you're receiving plain text, you can't tell whether it was "received correctly" or not. The UART can detect some kinds of errors - framing errors, and parity errors if parity is used, and it can report overrun errors, and you may be able to test for invalid received characters or incorrect...
  9. KrisBlueNZ

    What is your favourite type of component?

    Good point Adam! Op-amps are very versatile and many of the modern ones have amazing performance figures.
  10. KrisBlueNZ

    blew a resistor and cant tell what it is for a 4 led battery indicator i got from an old PW toy

    I don't see any burnt-up resistor, or inductor. Are we talking about the green resistor just to the left of the "3P-F0355-..." marking? If so, I agree with Steve.
  11. KrisBlueNZ

    Power Regulation Strategy

    It depends on many factors. Although the frequency of the switching cycle may be only 100 kHz, there are some very rapid voltage and current changes which have large frequency components well into the tens or even hundreds of MHz. These are the one that cause the problems when inductance and...
  12. KrisBlueNZ

    Power Regulation Strategy

    High currents aren't the only problem. How about capacitance and inductance? Well good for you! Breadboard isn't a suitable way to construct a switching power supply regardless of the current, and regardless of how carefully you lay it out. That's true. The original data sheet from Unitrode...
  13. KrisBlueNZ

    Best solution for square wave generator

    There are a thousand answers to this question. It all depends on what you're trying to achieve. Start by telling us about the whole project, then we will be able to recommend a suitable way to do what you want to do.
  14. KrisBlueNZ

    Installing Cabinet LEDs in my Workvan

    Hi there and welcome to Electronics Point :) I'm not sure about your arithmetic. You say you have six lights, and each one needs 4.5V. You have two circuits, with presumably three lights on each circuit. 3 × 4.5 is 13.5. Dropping your automotive supply down to 4.5V using diodes is not a good...
  15. KrisBlueNZ

    4060 counter not accurate?

    The PLL is used if you need to derive a higher frequency from a very accurate lower frequency. A mains frequency of 50 or 60 Hz is too low for many applications, hence the PLL. Some GPS receivers provide a 1PPS (one pulse per second) output which is even slower. Some provide a 1 kHz signal as...
  16. KrisBlueNZ

    Schottky rectifier

    AFAIK synchronous rectification with MOSFETs is used in switching supplies to improve efficiency by avoiding the forward voltage drop of the catch diode or rectifier diode. I guess the phrase might be used in other contexts as well.
  17. KrisBlueNZ

    amp repair, part ID

    So the IRF3205 is available in TO-220 package in two versions, one with a 'Z' suffix and one without. I don't see any 'Z' on the ones in your photo, so the replacement would be http://www.digikey.com/product-detail/en/IRF3205PBF/IRF3205PBF-ND/812033 The resistors aren't critical; suitable ones...
  18. KrisBlueNZ

    Schottky rectifier

    I don't think Steve meant to imply that the 1N5819HW is a silicon carbide diode. He was just mentioning silicon carbide diodes as another topic.
  19. KrisBlueNZ

    help with voltage divider

    You can get buck converters rated for 3A with adjustable output voltage for less than $2 on eBay. Search on eBay for LM2596.
  20. KrisBlueNZ

    amp repair, part ID

    Do you know why they all failed? Are you sure there are no other faulty or damaged components?
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