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  1. KrisBlueNZ

    Rice Cooker

    There's quite a bit of discoloration around the earth connection. Is the cooker actually overheating? Does the water boil in it? Does it have a thermostat? Has that failed? Is it rated for the correct AC mains voltage?
  2. KrisBlueNZ

    Sign with 175 LEDs

    You should be able to figure that out by looking closely at the socket. From the photo, I can see that one of the connection tabs is connected to the centre contact. This will be +19V to the switch. The 0V connection tab is the one that connects directly to the part of the socket that makes...
  3. KrisBlueNZ

    Comparator inputs

    Yes, one side of each current transformer's secondary connects to the VAR rail, so they are connected together. The VAR rail should measure about 2.8V DC relative to the 0V rail of the circuit. This should also be the DC voltage at pins 1 and 7 of the IC. Connect an oscilloscope to pins 1 and 7...
  4. KrisBlueNZ

    Send data with one wire protocol?

    There are several problems with your code. The major problem is the approach you seem to have taken is not workable. I need to know the exact details of the peripherals you have to work with, so I need the full part number of the device you want to use, as well as the schematic of the 1-wire...
  5. KrisBlueNZ

    Analog and Digital Ground

    There is TONS of guidance available on how to deal with AGND and DGND. Do some Googling!
  6. KrisBlueNZ

    Relaxation oscillator Noob need education

    The solenoid needs a significant amount of current (hundreds of milliamps, or maybe amps) to produce significant magnetic flux density. If you want to drive it with a sinewave, you really need an audio amplifier, the type that's used to drive a loudspeaker. Then you feed your control sinewave...
  7. KrisBlueNZ

    12 volt voltage "clamp?"

    Low dropout regulators are available with dropout voltages of typically 0.5V, maximum 1V or so. Digikey have some devices that might be suitable. See https://www.electronicspoint.com/sorting-things-out-small-circuit-t256173.html#post1521932
  8. KrisBlueNZ

    Send data with one wire protocol?

    OK I'm having a look at your code. Your comments are very minimal. This makes it hard for me to figure out what your code is doing, because I don't know what you're trying to achieve. Comments on individual lines are helpful, but larger blocks of comments before functions and at the start...
  9. KrisBlueNZ

    plasma speaker

    Yes, you could use a MOSFET driver. The TL494 is not an ideal device to be using here but you can probably interface it to a driver IC. The Microchip MCP1407 looks like it would be suitable. Use one output from the TL494. Connect the transistor collector to the positive supply. Connect the...
  10. KrisBlueNZ

    Sign with 175 LEDs

    That power supply looks suitable. At that price though, it will be the lowest quality you can find. Since this is a very non-critical application you may find it worthwhile. Based on my experience of extremely low-budget Chinese laptop power supplies, you may find that the mains cable will...
  11. KrisBlueNZ

    Repairing speakers

    In general, if there is an intermittent problem that comes and goes when you bend a particular cable, it is due to either a break somewhere along the cable, a break in the cable at or near the point where the cable enters the strain relief on the plug (and I use that term loosely; often the...
  12. KrisBlueNZ

    plasma speaker

    Your schematic diagram doesn't show how the MOSFETs are connected or specify what they are. You should know that we can't tell you whether it will work based on an incomplete diagram. But I think you're trying to use a push-pull drive. This won't work for several reasons. The P-channel MOSFET...
  13. KrisBlueNZ

    Uni Project Help!

    There are two approaches I can see here. The first is the approach used in simple heating appliances like bar heaters and electric blankets. Each heating element actually contains two (or sometimes more) resistive elements, and they are connected to the power source in different ways depending...
  14. KrisBlueNZ

    Elapsed time recording device

    Hi Michael. FYI I suspect (don't know for sure) that CC will want to keep any discussions on the public forum where they may be of value to other users. Generally if you want private one-on-one help you have to pay for it! We are all volunteers here.
  15. KrisBlueNZ

    Impulse Polarity Switch

    Sure, that's possible. What is the nature of the pulses? What voltage, what current? Is any particular shape required? What happens if you release the switch before the 100 ms pulse has finished? Does that pulse stop immediately and the one of the opposite polarity begin? Are the up and...
  16. KrisBlueNZ

    Current limiting for transistor base

    The ULN2003 and ULN2004 have base current limiting resistors built in. The 2004 is probably the most suitable if you're just driving LEDs with it.
  17. KrisBlueNZ

    Wanted$$: Super simple 8 input & 8 output select

    I suspect he may have found someone else to do it. In which case it would be common courtesy, not to mention professionalism, to tell me so. As you might expect from someone who has a "legitimate business enquiry". I'm not surprised, of course. Like BobK, I was hoping this thread might be of...
  18. KrisBlueNZ

    How to stop enclosure from dropping power when bumped

    I used to have this problem with my smartphone. Because of the mass of the battery, one decent bump on the phone was enough to very briefly break the connection between the battery holder's contacts and the battery, and cause it to reset. I fixed it by jamming something in beside the battery so...
  19. KrisBlueNZ

    Wanted$$: Super simple 8 input & 8 output select

    I've heard nothing from Rob H since I made my offer a week ago.
  20. KrisBlueNZ

    Send data with one wire protocol?

    OK, I've had a look at your code but it is not well documented. I would like to see some general documentation about how it all works, and comments at the start of each function describing what the function does, how it does it, what the parameters and return value means, and anything else that...
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