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  1. KrisBlueNZ

    Arghhh! I Hate RS232 :)

    I think you need to re-read post #1. It mentions RS-232 several times.
  2. KrisBlueNZ

    ATX PSU Power Toggle Circuit

  3. KrisBlueNZ

    Arghhh! I Hate RS232 :)

    Thanks for the pointer. It's outside my budget but I found an earlier edition for a few bucks, which will at least give me the basics. So the firmware in the device isn't meant to work with a modem at all? So I guess the modem can be configured to automatically connect to a WiFi host, and...
  4. KrisBlueNZ

    Need Some Help Figuring Out How to Use the PDSP2112

    Your code in the display subroutine first sends the LSB of the value you provide. This bit is in bit0. Then it divides w0 by 2, which shifts all the bits down in w2, so the value that was in bit1 is now in bit0, then it loops. So it sends the bits in w0 starting with the LSB and ending with bit...
  5. KrisBlueNZ

    Arghhh! I Hate RS232 :)

    That's an RS-485 transceiver, not RS-232. But thanks for playing!
  6. KrisBlueNZ

    Stage Line 500W amp repair project

    The diode range is marked with the red circle, but I'm interested in measuring leakage. Your results in post #24 are good, but it's better if you use the 2000k range, marked with the green circle. Use the black lead in the COM socket and the red lead in the VΩmA socket, as normal. The meter...
  7. KrisBlueNZ

    Switching loads using Raspberry Pi

    No. Solid state relays have full isolation between the control pins and the "contact" pins, just like a normal relay does. That one is rated for 2500V AC isolation. Also those ones have zero crossing switching, and use an SCR as the control device. This means they are only designed to switch...
  8. KrisBlueNZ

    FM modulator light only and no transmitting

    I was concerned about the reversed pinout used for the 13003 transistor on that board so I did some more investigatin'. There is a "standard" pinout for this type of transistor (which is called a TO-126 transistor outline), and this is it: The Fairchild KSE13003...
  9. KrisBlueNZ

    Arghhh! I Hate RS232 :)

    Thanks :-) Do you remember the book or author's name? I tried learning about TCP/IP and didn't get very far! Right, if it only has TXD, RXD and GND, it definitely doesn't support hardware flow control. I'm assuming that the firmware running on your board was written to work with a different...
  10. KrisBlueNZ

    Arghhh! I Hate RS232 :)

    It depends what flow control options are available on both ends of the link. The RS-232 standard is designed around communication between an end device like your circuit, which is called a DTE (data terminal equipment), and a device that provides a communication link, such as a modem, which is...
  11. KrisBlueNZ

    Need Some Help Figuring Out How to Use the PDSP2112

    It's better to keep track of the used/unused variables in a separate section before the code, using (for PICAXE) the SYMBOL statement to allocate them. It's traditional (but not universal) for serial interfaces to send data LSB (least significant bit) first. That's how your code works at the...
  12. KrisBlueNZ

    Arghhh! I Hate RS232 :)

    Yes, but that's the SSOP package. There's a narrow SOIC version that's more compact: http://www.digikey.com/product-detail/en/SN65C3232EDR/296-21000-1-ND/1216962
  13. KrisBlueNZ

    Arghhh! I Hate RS232 :)

    I assumed you wanted THT for ease of construction. But the MAX3232 is available in SMT, and Texas Instruments offer a version in -55~+125 °C temperature range: http://www.digikey.com/product-detail/en/MAX3232MDBREP/296-19873-1-ND/1120789. Still not cheap. Perhaps the TI data sheet will make more...
  14. KrisBlueNZ

    ATX PSU Power Toggle Circuit

    Yes, the Q and -Q (aka Q-bar) outputs are always in opposite states. The power supply is fully enabled when Q1 is conducting, which corresponds to positive voltage through R4, which corresponds to the Q output being high. At that time, the -Q output will be low, and you've connected the STANDBY...
  15. KrisBlueNZ

    Arghhh! I Hate RS232 :)

    Maxim's MAX3232EEPE is a good choice, though genuine Maxim parts are not cheap: http://www.digikey.com/product-detail/en/MAX3232EEPE%2B/MAX3232EEPE%2B-ND/1512691 USD 6.29 for 1-up quantity. Data sheet at http://datasheets.maximintegrated.com/en/ds/MAX3222E-MAX3246E.pdf This device can be...
  16. KrisBlueNZ

    Need Some Help Figuring Out How to Use the PDSP2112

    There's no actual need to initialise w0 and b2. They are both set before they are used. When you set w0 to various values - 2072, 1196, 3132 etc - you can actually specify the values in binary using a '%' prefix: w0 = %100000011000 ; 'H' Let's look at the mapping of the bits in those values...
  17. KrisBlueNZ

    FM modulator light only and no transmitting

    Ah! That makes sense, at last! So C2 capacitively couples the RF onto the +12V wiring. Thanks Adam! OK, I think it's best to rebuild that circuit on a bit of stripboard. Here's the schematic. I've guessed at the value of C2; if you can borrow a capacitance meter, you can measure the...
  18. KrisBlueNZ

    Need Some Help Figuring Out How to Use the PDSP2112

    That looks good Dan! The initialisation code can just say w0 = 0 instead of setting bit0~bit12 to 0 individually. I think you should be able to change the "if bit0=1 then high SDI else low SDI" to something straightforward like "let SDI = bit0". Not sure though.
  19. KrisBlueNZ

    Problem?

    I see this sort of problem occasionally, and not just with Electronics Point. I think it's caused by the style sheet failing to load for some reason. Good advice from Gryd3 there.
  20. KrisBlueNZ

    Switching loads using Raspberry Pi

    That's an interesting thought Bob. I haven't really noticed beginners often doing that, but I agree it's the natural way to look at it. Perhaps some manufacturer should create a two-transistor, four-terminal device like this:
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