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  1. KrisBlueNZ

    capacitor help

    I don't think there is a standard, even a de facto one, for marking capacitor voltage ratings (apart from simply stating it; for example, "100V"). I don't know what the 2A in the marking means. It probably IS the voltage. If you knew the manufacturer, you might possibly be able to find what 2A...
  2. KrisBlueNZ

    Op Amp HiFi Project

    Right. An adapter rated at 12V DC and 1A or more will be fine.
  3. KrisBlueNZ

    Op Amp HiFi Project

    Yes, 12V is a reasonable supply voltage for a small audio amplifier. Since your speaker is rated for 5W, aim for an amplifier with a similar rating. A good way to get a good idea of the available components is to search on Digikey...
  4. KrisBlueNZ

    Project brief feedback - volumetric music visualizer

    Funny. I like to listen to music with my eyes closed, and/or with the lights off. Flashing lights are good for ambulances, but I don't find that they add anything to the listening experience.
  5. KrisBlueNZ

    Ultrasonic Transducers

    You would be better to generate the whole transmit signal in the micro. If it has a timer with an output compare feature, you can make it generate a frequency of 40 kHz exactly, or very close, from any clock frequency, and the frequency will be crystal-accurate, unlike the simple design you've...
  6. KrisBlueNZ

    Simple transistor circuit problem

    That would probably be a good fit. I assume you would be using an automatic pick-and-place service with your board assembly house, so a 100-pin gull-wing IC shouldn't be a problem. Are you still planning to use a single-sided PCB? Now that I know water is involved, I'm not sure how best to...
  7. KrisBlueNZ

    Simple transistor circuit problem

    OK, I was just checking that you'd considered that factor. Yes, it's best to power the individual sections from separate power supplies. Have you considered the heat dissipation? Also, what about getting mains power into the power supplies? How many watts total? If it's more than about 2400...
  8. KrisBlueNZ

    Home amplifier blowing fuse - HELP!

    It looks to me like the end of the link that's within the goop is discoloured (dark brown, a darker shade than the goop) but it's not corroded in any way. I think that's just the goop itself. The main reason I think it's goop not leakage is that it seems to have formed a web around the edges of...
  9. KrisBlueNZ

    Home amplifier blowing fuse - HELP!

    I was looking at the picture in post #7. That's dated January so I think it's the one you're talking about. I don't think it looks like leaked electrolyte. The shape of it looks like it has been applied deliberately, and there doesn't seem to be any damage to the board, or corrosion of the link...
  10. KrisBlueNZ

    Home amplifier blowing fuse - HELP!

    I'm not sure if there's any point saying this at this point in the thread, but that goop under the electrolytics isn't electrolyte, it's just hardened reinforcing goop that's put there during manufacture to hold heavy components so they don't vibrate around and cause dry joints. You can tell...
  11. KrisBlueNZ

    Simple transistor circuit problem

    Hi rasklangus. It seems you're serious about this... I have several comments and questions... 1. Have you worked out how much power all those LEDs are going to consume if they're all ON at maximum current? And how you're going to provide that much power? Power supplies aren't cheap either; you...
  12. KrisBlueNZ

    How to not hear Mylie Cyrus when I am playing guitar?

    It couldn't hurt. If you've been working inside the guitar and have been moving things around, you may find that some of the strands of the wires will break between the end of the insulation and the component they're soldered to. It's probably worth fixing them too, by throwing away the crappy...
  13. KrisBlueNZ

    BEAM Solar Engine Circuit Help

    Good thinking, Steve.
  14. KrisBlueNZ

    18650 battery pack 5A charger

    Yes, the LT3651 looks nice if you're going to charge the cells separately. It has an on-board MOSFET which is a big advantage for simplicity and ease of use. It's not standard stock at Digikey or Mouser though. Do you have another supplier in mind?
  15. KrisBlueNZ

    18650 battery pack 5A charger

    Yes. I'm not very familiar with Li-Ion chemistry so you should do some research, but generally, when cells are connected in series, as the individual cells age, their characteristics deviate further from each other, which leads to some cells being overcharged and some being incompletely charged...
  16. KrisBlueNZ

    18650 battery pack 5A charger

    I assumed you wanted to charge them separately for best performance. Also 4-cell chargers are less common than 1-cell and 2-cell chargers.
  17. KrisBlueNZ

    18650 battery pack 5A charger

    Yes, but it doesn't charge cells singly. I'll have a look and see what I can suggest.
  18. KrisBlueNZ

    18650 battery pack 5A charger

    Chinese batteries? AND from eBay? You'll be lucky if you even get 2.5 Ah! Stick with the reputable brands to avoid imaginative specifications, and buy from reputable companies to avoid counterfeits of the reputable brands! It's not just the capacity that will be a lie. Do you care about the...
  19. KrisBlueNZ

    18650 battery pack 5A charger

    The two Linear Technology devices are limited to 1.5A and 4A charging current respectively. The Texas Instruments device has an external MOSFET so you should be able to go higher, though the sample circuit only charges at 1.2A. The Panasonic 18650 is specified at only 2.5 Ah. Which brand claims...
  20. KrisBlueNZ

    BEAM Solar Engine Circuit Help

    You should also take Steve's advice about putting a resistor between the PNP's collector and the NPN's base. This was my first reaction on seeing that circuit. When the transistors turn ON, a significant amount of energy will be wasted due to the heavy current flow into the NPN's base. Since...
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