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  1. KrisBlueNZ

    Diode selection

    If you're referring to a diode connected "backwards" across each winding of a stepper motor to protect the driver IC from back EMF from the coil, the important characteristics are: 1. Maximum reverse voltage. When the winding is energised by the driver IC, the diode is reverse biased. The...
  2. KrisBlueNZ

    LM358 problem

    Do you need the LED's cathode to be connected to 0V? If not, you would be better to put the shunt resistor between the cathode and 0V and measure the voltage across it directly. That differential amplifier has another source of error in addition to the op-amp's input offset voltage, nicely...
  3. KrisBlueNZ

    D.C. treadmill motor power supply

    They are MOC3041s. You can read the part numbers (barely) in the photo.
  4. KrisBlueNZ

    UART

    There are several products available. Try a Google search on multiple USB serial ports The first page of results has a four-port model and one that supports up to 16 ports.
  5. KrisBlueNZ

    Tiny85 and LDR Analogue Read

    Hi Harold and welcome to Electronics Point :-) As Bob says, you don't need any special features to use the AVR's on-board peripherals, including the ADC. You just need to set the control registers correctly, and connect your LDR to a suitable pin. The ADC measures voltage, not resistance. So...
  6. KrisBlueNZ

    Another treadmill problem

    I'm only interested in DC voltage measurements taken with the negative (black) multimeter lead on pad 3. These pads are counted starting from the end closest to the corner with the three connectors (for the display board and the signals from the motor assemblies). That sounds exactly...
  7. KrisBlueNZ

    Semiconductor

    OK you're right, that's the TO-220 version, IPP80N06S4-05. The Infineon IPP052NE7N3 G looks like a good replacement. Every specification is better than the original device except for a few unimportant ones. It's available ex-stock from Digikey for USD 2.67...
  8. KrisBlueNZ

    Another treadmill problem

    That doesn't make sense either. When you desolder pin 2 of the daughter board connector from the pad on the main board, you are removing the load on the 78L05 regulator. The surrounding pad on the main board is powered from that regulator. So I would expect one of two possibilities. 1. Around...
  9. KrisBlueNZ

    maximizer

    Hi witsender and welcome to Electronics Point :-) Cool nick! Some in-focus, well-illuminated photos would be a good start. Best lighting is outside on a bright overcast day, where the clouds scatter the light so it's coming from all angles. Avoid direct sunlight because it reflects off the...
  10. KrisBlueNZ

    Another treadmill problem

    I think you may have made a mistake. The pin you need to desolder is the second from the end. You need to desolder it on the main board, and make sure the metal pin from the daughter board is not making contact with the surrounding pad on the main board. The third pin is 0V ("zero volts")...
  11. KrisBlueNZ

    Another treadmill problem

    Ah yep, you're right. I had the +12V and +5V points backwards. So there's 12V there, but the 5V rail is only 1.46V. This means that either there's something wrong with the 78L05 regulator (that looks like a transistor) on the main board, or something is loading down the 5V rail. That something...
  12. KrisBlueNZ

    An interesting pipe dimmer project

    My suggestion is to skeleton-wire it. In other words, no board. But see the caveats I listed in post #47.
  13. KrisBlueNZ

    Simple power supply questions

    Great! Well done. You're welcome. I don't have any recommendations for books or other learning resources, but others here probably do.
  14. KrisBlueNZ

    An interesting pipe dimmer project

    Yes, those capacitors look fine. That diac is good but as I said in post #29 the circuit you are working from is designed to use a neon bulb, which has different characteristics. If you copy the component values from that circuit but use a diac instead of a neon, you'll probably find that you...
  15. KrisBlueNZ

    Another treadmill problem

    The second link in post #29 gives a "file not found" error. Thanks for those pics. Now I need you to measure the two supply voltage rails that feed into the daughter board. You'll have to apply mains power to the main board. Use your GFI! EDIT 2013-12-14: THE ABOVE DIAGRAM HAS +12V AND +5V...
  16. KrisBlueNZ

    An interesting pipe dimmer project

    The capacitance, 0.068 µF (microfarads), should match exactly. That value is also called 68 nF (nanofarads). You can use a component rated at a higher voltage, as long as it's not too big.
  17. KrisBlueNZ

    An interesting pipe dimmer project

    That drawing looks good except that the diac connects to the gate. That is the wire that enters at an angle in the schematic symbol. It's pin 3 according to the data sheet. (The data sheet shows the symbol rotated anticlockwise from the normal orientation. Bad Philips Semiconductor!) MT1 (Main...
  18. KrisBlueNZ

    Automated Sliding Door

    Cool! I'm looking forward to hearing how it goes. Good luck!
  19. KrisBlueNZ

    An interesting pipe dimmer project

    Yes, the light green areas on the solder side of that circuit board are areas of copper that connect the components together. You're right. L2 is a neon bulb and you can replace it with a diac, but a neon bulb has a breakdown voltage of about 90V and diacs usually have a lower breakdown...
  20. KrisBlueNZ

    Automated Sliding Door

    Right. If you want to use the full stroke length, you don't need an external limit switch. Is 12" enough? Don't you need the door to open wider than that?
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