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  1. KrisBlueNZ

    Automated Sliding Door

    When you call the tech, you could suggest that they should mention the limit switches somewhere in their documentation! The quality of their documentation is pretty poor.
  2. KrisBlueNZ

    Automated Sliding Door

    "Rails" are just a way of describing parts of a circuit that have multiple connections between them. They aren't necessarily physical things! Sorry for the confusion. More complicated circuits, shown as schematic diagrams, usually have the positive and 0V rails drawn horizontally across the top...
  3. KrisBlueNZ

    Another treadmill problem

    OK, that's good. The fourth image in post #26 doesn't work. (Also, the fifth and sixth images are the same.) Can you please post the markings on the two black plastic devices (three-terminal regulators, I think they are) marked A and B in this photo. Also, can you please take a close-up...
  4. KrisBlueNZ

    HP 1741A Oscilloscope

    OK. I understand. Can you post some photos of both sides of the A12 board please.
  5. KrisBlueNZ

    Parasitic draw amp meter

    Well, you don't need any active circuitry to do that. This is all you need for a unipolar automotive current meter with a display range of 0~50 mA. F1 is a Polyswitch resettable fuse. It's rated for a hold current of 0.4A. Current through it causes it to heat up, and at a certain temperature...
  6. KrisBlueNZ

    An interesting pipe dimmer project

    LOL Sorry for the confusion! Steve's suggestions are a very good idea. Make sure there is LOTS of insulation between the circuitry and the pipe. After you've enclosed all the parts in potting mix, add one or more pieces of heatshrink tubing or plastic tubing around it all. What's the internal...
  7. KrisBlueNZ

    HP 1741A Oscilloscope

    So is the +5V regulator working now? Edit: Oops I didn't see your reply. This thread is up to five pages now! So +5V is correct with everything plugged in except A12? When you plug in A12 everything goes screwy? Edit2: Where exactly are you connecting your multimeter earth lead?
  8. KrisBlueNZ

    PIC mcu memory question

    I guess Steve knew that. I guess he was just being a smart-arse. I think you can assume that no one here knows of any way to read the RAM in a running PIC.
  9. KrisBlueNZ

    An interesting pipe dimmer project

    In post #5 I suggested potting mix.
  10. KrisBlueNZ

    Parasitic draw amp meter

    What advantage(s) do you think that project would have over a digital multimeter?
  11. KrisBlueNZ

    HP 1741A Oscilloscope

    I suspect the pin sockets were "machine screw" sockets that hold the wires in by friction. If there was something that looked like glue, it might have been some kind of lacquer to seal the hole and prevent corrosion. You probably didn't need to solder the leads in, but it won't matter...
  12. KrisBlueNZ

    Parasitic draw amp meter

    I agree there's a lot of rubbish in that video, and I don't see any reason to make a special device to do what a multimeter does. When you're measuring current in a fused circuit, set the multimeter to current range and connect it across the fuseholder before you pull the fuse. It will keep the...
  13. KrisBlueNZ

    Semiconductor

    Hi and welcome to Electronics Point. Why do you think it's an IPD90N04S6-05? That number isn't very similar to the marking. 4N0605 could easily be a factory and date code. The IPD90N04S6-05 is an N-channel MOSFET made by Infineon. Is your device in a TO-252 package like the Infineon part? Is...
  14. KrisBlueNZ

    HP 1741A Oscilloscope

    Yep, NTE comes to the rescue again! I'm surprised they second-source the metal can version! Yes, you might as well try connecting A12 without the HVPS to see whether the A12 board messes up the voltage rails by itself.
  15. KrisBlueNZ

    HP 1741A Oscilloscope

    OK, I guess we need to check the -15V and +5V regulators on the LVPS. We have to fix the +5V regulator first because the +5V rail voltage is used by the -15V regulator. The 5V regulator is a standard linear series regulator using Q5 (off-board) as the pass transistor, with U2 as the...
  16. KrisBlueNZ

    HP 1741A Oscilloscope

    There are some weird numbers in the middle column - the +120V, +156V and +48V rails are much too high! I guess this could be due to back-feeding from the HVPS, if the HVPS is running. What is the HVPS doing at the moment? Is it running and producing the ozone smell and the illuminated neons, or...
  17. KrisBlueNZ

    400 volt monitor

    That looks good.
  18. KrisBlueNZ

    Malloc and it's use with MCUs

    I think it would be cleaner if you only allocated blocks of a single size - the largest size you need - then just use part of the block if you don't need all of it. You're welcome :-)
  19. KrisBlueNZ

    Malloc and it's use with MCUs

    As I said in post #5, the problem can occur if you're malloc()ing and free()ing blocks of two or more different sizes. If you're always malloc()ing and free()ing blocks of the same size, then I don't see any way for the heap to get fragmented. Provided that malloc() and free() work the way you...
  20. KrisBlueNZ

    400 volt monitor

    The problem is as gorgon described. The switching action of the comparator causes the input conditions to change, which causes the comparator to switch back again, and the cycle repeats. This can be fixed by making the comparator latch, or by adding hysteresis. Hysteresis makes the threshold...
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