Search results

Search Forums New Posts
  1. KrisBlueNZ

    Smoothing Capacitor/Vripple

    I think you understand what you're doing. The confusion is arising because of how the question is worded. Your teacher's interpretation is different from how you and I interpret it. Just hope that the exam questions will be more clearly worded.
  2. KrisBlueNZ

    Smoothing Capacitor/Vripple

    Oh well. I guess it depends on your priorities. Do you want to be right, or do you want to pass the course? LOL
  3. KrisBlueNZ

    Trying To Cheat The Laws Of Physics . . . Again. Multi Voltage Power Supply

    The magic of inductance :-) https://www.google.com/?q=efficiency+of+switching+vs.+linear+power+supplies
  4. KrisBlueNZ

    load cell circuit

    Rule of thumb, i.e. "it's close enough". The relevant calculation is the input current into the protection network in the Arduino. This network clips the input pin voltage to about (VDD +0.6V) and (VSS - 0.6V). In the worst case, assuming no losses in the voltage rail generator and assuming...
  5. KrisBlueNZ

    Smoothing Capacitor/Vripple

    I guess it depends on how you interpret the specification: Since ripple is normally specified in volts peak-to-peak, I would interpret that as you did - the ripple must be 1.2V peak-to-peak or less. Another interpretation is that the voltage at the peaks must be no higher than (12V +10%) and...
  6. KrisBlueNZ

    LM358 Breathe light

    Yes, C1 shouldn't really be a polarised electrolytic, since it is charged in both directions. It would be better to use a non-polar electrolytic: http://www.digikey.com/product-detail/en/UVP1C101MPD/UVP1C101MPD-ND/2428047
  7. KrisBlueNZ

    load cell circuit

    Yes, that's the right idea.
  8. KrisBlueNZ

    Smoothing Capacitor/Vripple

    Hi Claire and welcome to Electronics Point :-) So you need to provide at least enough smoothing capacitance to ensure that the "AC ripple" is kept to "within 10% of the desired voltage". I assume this means that the peak-to-peak ripple voltage must be 1.2V or less. You've assumed that too...
  9. KrisBlueNZ

    Designing a Time Delayed Relay

    With projects like this, I just start by creating a source file. One source file is enough; there's not enough complexity to justify splitting the functionality into multiple modules and that just makes it harder to edit. I start by defining and describing the hardware - the target device...
  10. KrisBlueNZ

    load cell circuit

    The INA125 can't drive its output fully to either its positive or its negative supply voltages. If you want it to drive its output from 0V to 5V, its positive supply must be more than +5V and its negative supply must be less than 0V, i.e. negative. So you need a boosted positive supply, and a...
  11. KrisBlueNZ

    Designing a Time Delayed Relay

    No, you just exclude the vias from the solder masks. If Eagle doesn't have an option for this, you can do it by generating all of the fabrication files, temporarily deleteing all the vias (I assume Eagle has some kind of global or wildcard selection feature), and regenerating just the solder...
  12. KrisBlueNZ

    Designing a Time Delayed Relay

    They can't tent them now; they would have to re-run the production run. And since the files you gave them had the vias un-tented, they would charge you again for another run since it's not their fault. In any case it's not a big deal.
  13. KrisBlueNZ

    LM358 Breathe light

    OK, we can diagnose the problem. I assume you have a multimeter? Set it to DC volts (20V range, if it's a manual ranging meter), connect the black probe to the 0V rail on pin 4 of the LM358, and measure the voltages on the other pins. Post a list of pin numbers and voltages, then we can tell you...
  14. KrisBlueNZ

    Converting a projector from incandescent to solid state?

    How rude! It only takes a few minutes to copy a CD :-(
  15. KrisBlueNZ

    Trying To Cheat The Laws Of Physics . . . Again. Multi Voltage Power Supply

    Or multiple switching regulators, assuming you need all of those voltages simultaneously. Switching regulators aren't the best for some applications - audio, in particular. Tell us more and we can advise more :-)
  16. KrisBlueNZ

    Current limiting strategies for L298N?...

    Try aliexpress. They sell similar products in smaller quantities. Caveat emptor!
  17. KrisBlueNZ

    Converting a projector from incandescent to solid state?

    Wouldn't you rather have those slides as digital images? Google slide scanner, or slide scanning services.
  18. KrisBlueNZ

    LM358 Breathe light

    That circuit is a two-op-amp integrator/Schmitt trigger oscillator with an emitter follower, and it should work. The way it is shown, adjusting the frequency will affect the brightness range. That can be fixed by exchanging R4 with the series combination of R5, VR1 and R6. (R6 can also be...
  19. KrisBlueNZ

    Image gallery on project logs

    Are you _sure_ the file contents matches the extension? The only time I've had problems uploading the picture is when the file is internally not one of the supported types (although the extension was).
  20. KrisBlueNZ

    Stage Line 500W amp repair project

    OK, those numbers seem to make sense, and they're pointing to a problem earlier in the output stage. I need you to make some more measurements, I'm afraid.
Top