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  1. KrisBlueNZ

    Renewable Energy

    You can start by telling us everything you know about your project. There are many answers to that question and lots of important variables that we don't know about. For example: What is the battery voltage? What is the battery capacity in amp-hours? What is the power output of the turbine...
  2. KrisBlueNZ

    Renewable Energy

    You won't need diodes to rectify the supply from the motor, but if you're charging a battery from that motor, you will need some way of preventing the battery from back-feeding into the motor. If you're using some kind of charger (and you probably should), it probably includes that feature. You...
  3. KrisBlueNZ

    What's the name of the round plug at the end of an AC-DC adapter?

    Yes, you've got it. I've heard them called DC plugs/sockets and barrel connectors.
  4. KrisBlueNZ

    PC Speakers malfunction. Need help

    No, it's not good for a polarised capacitor to have reverse voltage across it, but 0.8V isn't going to do any harm, especially with a capacitor that's rated for 16V or more. Right, that's 470Ω. You read the stripes in the other direction. Yellow = 4, purple/violet = 7, and brown = 1, and for a...
  5. KrisBlueNZ

    74HC393: 4-Bit Counter in need of debounce?

    Yes, I see your point.
  6. KrisBlueNZ

    Extending IR receiver

    Oh, it's a LED dimmer! That should be safe enough. You should be able to connect a second IR receiver device in parallel with the first, so you can control the dimmer from either location. If you want to do that, find out the part number of the receiver unit, so we can choose a suitable device...
  7. KrisBlueNZ

    PC Speakers malfunction. Need help

    No, don't get obsessed with replacing capacitors! This isn't a switching power supply or a computer motherboard. I suspect the resistor I've marked with an arrow. Can you desolder one end and lift it out of the board, then measure resistance (the Ω range) across the resistor itself? And post...
  8. KrisBlueNZ

    74HC393: 4-Bit Counter in need of debounce?

    Hi Simon, Yes, you do need a decoupling capacitor. Typically 0.1 µF ceramic. Connect it as directly as possible between pins 14 and 7 (sorry, not 16 and 8) of the chip using wires as short as possible. Putting the LEDs like that in the multivibrator isn't normal but it should work equally...
  9. KrisBlueNZ

    PC Speakers malfunction. Need help

    Are those voltages both positive? The voltage on pin 4 should be negative, so the multimeter should show a "-" sign when you measure it. Can you check them both again?
  10. KrisBlueNZ

    Extending IR receiver

    What's the manufacturer's name and the model number of the dimmer?
  11. KrisBlueNZ

    Op amp output into op amp input?

    Probably, negative feedback around the second op-amp. Without it, the second op-amp will just act as a comparator, and its output will swing hard against one of the rails because there is nothing to reduce its gain. Or I may have misunderstood your question. Can you post a schematic, including...
  12. KrisBlueNZ

    PC Speakers malfunction. Need help

    Those pictures are a lot better. Don't worry about the voltages on the six-pin connector. Those pins only carry low-level audio signals, which are AC, so there shouldn't be any DC voltage on those pins. What is the 2-pin connector near the middle for? Does that go to the LED? There might be a...
  13. KrisBlueNZ

    Output of logic gate as ground?

    Good point Bob, thanks. That is true whether you connect the LED+resistor from the output to 0V/VSS, or between VCC/VDD and the output. Different logic families, and different I/O structures inside devices, have different characteristics, and this affects the maximum current they are specified...
  14. KrisBlueNZ

    Homemade Battery monitor for 4 x 3.2V cells

    Ah, it worked just then too. The site must have been down temporarily. I guess that's an option. There are other ways that might be cheaper, or smaller, or simpler, depending on your priorities. Here are a few that come to mind. "Flying capacitor" method using one DPDT relay per cell. Google...
  15. KrisBlueNZ

    How to set up a Beacon light to run from the mains

    Not at all! That's great! I like your web site. Nice and clean, good balance between text and graphics, well-written. I like the face close-up on the About page - all monochrome except for the eyes. I have an idea for a project that I would like to talk to you about. ("Oh no!" he says, "He...
  16. KrisBlueNZ

    Extending IR receiver

    Are you talking about moving the IR receiver out of the dimmer and putting it somewhere else so you can control it using the remote control in another room? There are several factors involved here. The first one is safety. It's very likely that the dimmer circuitry is powered from the mains...
  17. KrisBlueNZ

    Output of logic gate as ground?

    Hi there and welcome to Electronics Point :-) Yes and no. It depends what you're asking. It is fine to connect an LED (with a series resistor for current limiting) between VCC and a gate output, and yes, when the gate output goes low, the LED will light. This is often done in practice. In...
  18. KrisBlueNZ

    A tip if the "upload a file" button does nothing

    Seems to be good so far. Thanks Ian!
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