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  1. KrisBlueNZ

    (Electro)Magnetic Levitation

    You know John meant flipping the orientation of the Hall sensor in the magnetic field, not changing the connections to its pins, right? That circuit should already give you that behaviour. When the Hall sensor outputs a high voltage, you should see that voltage on pin 3 of the IC. Pin 2 of the...
  2. KrisBlueNZ

    flip relay with 2n3904

    Yes, there is a lot wrong with driving a relay coil directly from an Arduino. It won't work. The Arduino's outputs are not able to supply very much current - you shouldn't try to draw more than about 10 mA from them - and the relay coil needs significant current. You can calculate the coil...
  3. KrisBlueNZ

    Just posting to see if anyone is interested in my channel at all.

    Making loud noises and damaging things doesn't have much excitement when translated to video IMO. I think you really need to be there to enjoy it. You seem to know at least a bit about electronics. Do you have any educational or DIY project videos? P.S. Welcome to Electronics Point :-)
  4. KrisBlueNZ

    Lost amateur :)

    When you say "clicker", you mean something like a remote control for a TV set, right? And you need that to operate over the same distance that you want to be able to hear the beep, right? Why do you want it to be disposable? Why does it need to be so light? Would it be better for the unit...
  5. KrisBlueNZ

    impedance of a constant current source

    OK. As far as I can tell from your comments, especially in post #24, you do not understand how transistors, current sources, current mirrors, and common emitter amplifiers work. You can't just jump into amplifier design without learning the basics. That starts with understanding voltage...
  6. KrisBlueNZ

    Dash light rheostat or other dimming device assistance requested

    Hello there! Welcome to Electronics Point :-) Thanks for identifying the bulb type. All the "194" bulbs I've found are rated for 14V and 0.27A (amps). When they're connected in parallel, the currents add together. So eight of them will draw 2.2A at 14V. If you connect a rheostat, the rheostat...
  7. KrisBlueNZ

    Portable Speaker Setup

    Hi nikolay_b and welcome to Electronics Point :-) Are you SURE the speakers are 25 ohms? That's a very unusual impedance. Do you want stereo or mono? Have you chosen a LiPo battery?
  8. KrisBlueNZ

    Audio - mono to dual mono

    Hi Erik. We meet again :-) You have a single phantom-powered condenser mic with a 3-pin Cannon XLR connector? And you want to adapt it so it can plug into two inputs on a mixing desk or similar, and produce the same signal into each input? I haven't tried this, so YMMV ("your mileage may...
  9. KrisBlueNZ

    impedance of a constant current source

    I can't make sense of that last post at all. What are you trying to achieve? Are you a student? Can you give me a link to the assignment you're working on? Can you give links to the other material you have been reading?
  10. KrisBlueNZ

    impedance of a constant current source

    OK. So what are you trying to do? You want to build an amplifier circuit using a constant current source as the collector load? You know that will give a pretty high voltage gain. So you need to feed a low signal level into it, otherwise it will clip, as you said. In post #13 you said that...
  11. KrisBlueNZ

    flip relay with 2n3904

    Oh dear. Chinese quality control strikes again. That data sheet has been copied from the data sheet for a relay with a 12V coil but most of the numbers, and the photo, haven't been changed. So it's inconsistent. On the first page, the part number includes "05VDC" which is pretty clear in its...
  12. KrisBlueNZ

    impedance of a constant current source

    sabahan, I have attached your new posts to the existing thread that you created on this subject. Did you learn anything from the reference that Steve linked to in post #16? Your first question on the new thread (post #18) seems to indicate that you didn't. The schematic in post #20 won't do...
  13. KrisBlueNZ

    Timer circuit

    There's information on the 555 all over the net. This one looks good: http://electronicsclub.info/breadboard.htm It shows you how to connect a pushbutton and a pullup resistor to pin 2 so you can trigger the monostable by pressing the button, and how to connect an LED with a current limiting...
  14. KrisBlueNZ

    (Electro)Magnetic Levitation

    No, it shouldn't be heating up if the circuit is oscillating as it should. It's possible that the 1N4148 has failed open circuit and that might be the reason for the MOSFET getting hot. I wouldn't connect an LED across the output of the Hall sensor. Do you have an oscilloscope?
  15. KrisBlueNZ

    Re-wiring a powered Subwoofer

    Yes. Ground, 0V rail, common, return, ...
  16. KrisBlueNZ

    Re-wiring a powered Subwoofer

    Yes, pin 4 is the audio signal for the subwoofer. It's not "positive", but it is ground-referenced. Ground is the reference for the signals, and the negative return for the +12V supply.
  17. KrisBlueNZ

    (Electro)Magnetic Levitation

    I think the second pot will have a similar effect to the first one. Over most of its range, it will only affect the strength of the feedback. So it might affect the amount of up-down movement in the suspended magnet due to the 70 Hz oscillation. Setting it too close to the bottom end would...
  18. KrisBlueNZ

    Component questions (transistor, capacitor)

    That's brilliant Erik! I'm keen to know how it works out :-)
  19. KrisBlueNZ

    Capacitors and Leds

    Hi Stephen. What is the minimum supply voltage?
  20. KrisBlueNZ

    Logitech Z5500 diagnosis help

    I expect it would be custom made. If you don't feel like unwinding and rewinding it, you could add another small transformer to provide the 15V AC. There's probably not much load on it. You won't get an accurate reading if you connect an AC ammeter in the circuit between the 15V AC secondary...
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