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  1. KrisBlueNZ

    westing house tv works but smells of smoke

    It wasn't a surge. It could have been an internal defect in the PCB material, or maybe a spillage on the board. If the display lights up properly, the transformer is OK. Have a close look at the part of it that was near the area of the burn-up though. It matters because of the high voltages...
  2. KrisBlueNZ

    westing house tv works but smells of smoke

    It looks to me like the PCB has burnt up quite badly. If that's the case, you'll need to remove every bit of discoloured PCB, otherwise the problem will just recur. You'll need to remove the transformer first (be gentle with it), and use something like a Dremel to grind away the fibreglass PCB...
  3. KrisBlueNZ

    Basic LCD driver question

    As far as I can tell from the data sheet, the only "programming" the HD44780U contains is the character ROM and there appears to be only one version of that. There is no code, as such. Its behaviour is controlled by registers that are programmed by the host. I hope you have the tools to replace...
  4. KrisBlueNZ

    Inductor - 4 Pins???

    Yes Steve, I think you're right. Mains common-mode chokes are specifically designed for filtering high-frequency noise in that application, and I believe they will saturate at a fairly low current if used as the inductor in a switching supply. We've already had this subject...
  5. KrisBlueNZ

    Identify plug

    Right Dave. http://www.altronics.com.au/index.asp?area=item&id=P0952
  6. KrisBlueNZ

    Battery Powered Power Supply

    Yes, exactly.
  7. KrisBlueNZ

    Battery Powered Power Supply

    OK, the schematic in post #86 is correct now. You might also want to add the resistor and diode as I described in the last paragraph of post #78 to ensure that the capacitor is fully discharged as soon as the circuit is turned off.
  8. KrisBlueNZ

    Battery Powered Power Supply

    That's still wrong. The diode and capacitor should connect to the cathode of the TL431, and to pin 8 of the 4013. The connection from the 4013 to the pass MOSFET shouldn't connect to anything else.
  9. KrisBlueNZ

    Battery Powered Power Supply

    R15 and R22 shouldn't be there. They're only needed if you use a MOSFET, to ensure that the gate voltage drops below the threshold. The 4013 has an input voltage threshold between 1/3 and 2/3 of the supply voltage, so no voltage divider is needed. Also the connection to pin 8 is shown wrong and...
  10. KrisBlueNZ

    Battery Powered Power Supply

    OK. Probably... I just wanted to make sure. Don't assume... it makes an ass out of u and me :-)
  11. KrisBlueNZ

    Battery Powered Power Supply

    If you're using the 4013 controller, you don't need a MOSFET to invert the signal from the TL431. In fact you mustn't have one. The voltages on that circuit show that there's a break (or possibly a short) somewhere. The diode has no effect while the supply voltage is present, so ignore that...
  12. KrisBlueNZ

    advice for project involving led

    A LED needs to be driven with a specific amount of current. This can be done with just a battery, a switch, the LED, and a current limiting resistor. But you need to know how much current the LED should be driven with, so you can choose the resistor value. If you can get a part number for the...
  13. KrisBlueNZ

    4536 Programmable Timer question

    Read the functional description in the data sheet. If you don't understand some of the terminology, Google it. Re-read it as necessary until you understand it. Also, get data sheets from other manufacturers. Some may have better explanations than others.
  14. KrisBlueNZ

    Battery Powered Power Supply

    I never suggested using Schmitt triggers in the circuit path from the TL431 to the 4013 and I don't think there's much point using them there. I only suggested them to debounce the signal from the ON/OFF pushbutton. I don't see any reason why that circuit would work better than a direct...
  15. KrisBlueNZ

    Identify plug

    I don't think it's a DIN connector, but I don't know the name of it. The male connector is recessed, unlike DIN connectors. As Dave says, they used to be used for some microphones. Look on a big component retailer like Digikey or Mouser (U.S.) or Element 14 (U.K.) and try to find a match visually.
  16. KrisBlueNZ

    My New Toy

    Belated Happy Birthday from me as well :-)
  17. KrisBlueNZ

    Battery Powered Power Supply

    That circuit looks OK. When the circuit shuts down, the supply voltage to the TL431 will disappear, so 4013 pin 8 will go to 0V. There will be a problem on startup though; the TL431 output will probably go briefly high, and this will reset the flip-flop and prevent the circuit from starting up...
  18. KrisBlueNZ

    Home amplifier blowing fuse - HELP!

    The +A and -A outputs are the main positive and negative rails coming out of this power supply. The -C output is an auxiliary negative voltage output. The right hand part looks like it's supposed to be a dual regulator producing +B and -B rails but it's drawn wrong.
  19. KrisBlueNZ

    Project brief feedback - volumetric music visualizer

    I thought you might say that. I suppose if I was out of my brain and listening to dubstep, I would really get into a visualiser. But I use music to relax, and I only want to hear it.
  20. KrisBlueNZ

    Noise Generator Circut Understanding

    Good answers Harald. As Harald said, the pulldown resistor on the output isn't normally used. It can be used to avoid crossover distortion in the output stage if you're using a cheap op-amp such as an LM324, but my solution is to use a good op-amp that's designed for audio applications. The...
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