Search results

Search Forums New Posts
  1. KrisBlueNZ

    Simple relay circuit help

    Your breadboard layout looks OK apart from the relay error which you fixed. Assuming you're using 2N3904 transistors. Also you have used 12k resistors instead of 3k3 resistors. The circuit will probably still work but you should change those resistors to 3k3. With R1 = 10k, the circuit will...
  2. KrisBlueNZ

    RCD Fault

    Can you move or extend the pipe so it's away from the socket? Even just putting the end of it below the socket should help, I would think.
  3. KrisBlueNZ

    HELP NEEDED - Faulty home theater

    It looks like you have a problem with bulging electrolytics. Nothing personal! The big black cylindrical component in the middle of the second picture, an electrolytic capacitor, is visibly bulging at the top, and has actually leaked some electrolyte. The blue one to the left of it is also...
  4. KrisBlueNZ

    RCD Fault

    Hmm. An overflow pipe near the power socket sounds like a BAD idea. And not Michael Jackson's idea of BAD. Yes if there's a crusty layer on the surface of the plug, it will probably contain salt and other impurities, and will be the reason for the leakage. If you still have the plug, you could...
  5. KrisBlueNZ

    Next/previous switching a multiplexer

    Yes, that's right. The LEDs (with current limiting resistors) should be connected between VCC and the OUTPUTS of gates D and E. As I said in post #34: Exactly. What I mean by a "standalone MIDI activity monitor" is a circuit that performs only that function. It has a MIDI input, which goes...
  6. KrisBlueNZ

    RCD Fault

    That's interesting. So there was leakage to ground within the moulded mains plug? Were there any cracks in it? Do you think moisture had got into it?
  7. KrisBlueNZ

    Help with replacement for a rotary switch

    Hello Vegard and welcome to Electronics Point :) Digikey is a great resource for finding out what components are available in a given category. There are two relevant sections on the Digikey web site: 1. Integrated Circuits (ICs) > Logic - Signal Switches, Multiplexers, Decoders...
  8. KrisBlueNZ

    zero crossing detector

    Look one up yourself! http://www.google.com/search?q=zero+crossing+detector+circuit&tbm=isch
  9. KrisBlueNZ

    cable question

    I don't think the operation will be affected, provided you join them cleanly. Life of the cable will definitely be affected; any join in a heavily used cable is the weak point that will probably fail first, due to bending, crushing, stretching etc. With a USB cable, no. There's no attached...
  10. KrisBlueNZ

    Small Circuit needed for New Product Design - Help!

    Right, fair enough. It looks like the LCD you found will work nicely from 3V and can be driven from any micro with enough I/O - 15 outputs for that display, or 17 if you want to drive the decimal points too. Add between 1 and 3 pins for the pushbuttons, and you could use any PIC or similar small...
  11. KrisBlueNZ

    Simple Circuit using transistors

    YW :-)
  12. KrisBlueNZ

    Need help with a radio project!

    No, those terminals are the on/off switch. I'm talking about the three terminals on the same side.
  13. KrisBlueNZ

    Measure time when ground connection is lost ?

    I guess you could try using a conductive rubber pad on the sole of one shoe (or both shoes if you want to make sure both feet are off the ground) and a conductive rubber pad for the person to stand on... Your monitoring circuit would need a wire from the shoe and a wire from the pad on the floor.
  14. KrisBlueNZ

    Need help with a radio project!

    That's a mono radio. The giveaways are (a) the volume control is mono (stereo pots have two sets of three terminals); (b) the audio amplifier IC is mono, and probably (c) there is only one speaker. You will have to merge the left and right channels together, using a resistor (e.g. 3k3) from each...
  15. KrisBlueNZ

    Simple Circuit using transistors

    If the voltage at point B is jumping from 0V to +5V on the rising edge of the input signal, that would be because the input signal has an amplitude of 5V. So, change the input signal generator to have an amplitude of 3.3V.
  16. KrisBlueNZ

    Simple Circuit using transistors

    I'm not sure what you mean by "huge overshoot". It jumps up to 3.3V when the input goes from 0V to 3.3V. That's not overshoot. Then it tapers off towards 0V.
  17. KrisBlueNZ

    Simple Circuit using transistors

    That's what I was thinking of. There would be other ways to do it, but that's a simple one. Here's a screen shot of a simulation of that circuit: The graph shows what happens when VIN goes from 0V to +3.3V at the 1 ms timing mark. The green trace shows the voltage at point B, the output of...
  18. KrisBlueNZ

    Small Circuit needed for New Product Design - Help!

    How about using periodic wake-up to run some code toggle the I/O signals? Executing say 10~15 instructions every 10 ms or so wouldn't require much current. And in any case I expect an inactivity timeout of a few minutes before the whole display turns off would be ok. I'm interested in this...
  19. KrisBlueNZ

    Motion sensor lighting with a difference

    I think your best bet would be to have some tiny holes in your surface. Is it really necessary for part of the lamp that's not normally even visible to be perfectly smooth with no holes or gaps? Alternatively... Have a look at https://en.wikipedia.org/wiki/Proximity_sensor - it may give you...
  20. KrisBlueNZ

    Small Circuit needed for New Product Design - Help!

    As far as I can tell, the smallest PIC that has an LCD driver built-in is a 28-pin one anyway. Thanks for that link :) Edit: I see what you're getting at. With a non-multiplexed display, you don't need any special LCD driver in the microcontroller. You just have to get the code to flip the...
Top