Search results

Search Forums New Posts
  1. KrisBlueNZ

    Re-wiring a powered Subwoofer

    Sorry, I must have lost track of this thread. Good work!
  2. KrisBlueNZ

    does this seem right?

    No, because if you use N-channel MOSFETs in the high-side position, you need a voltage higher than the supply rail to bias them ON, but the bias voltage for the low-side MOSFETs is just relative to 0V. Using four N-channel MOSFETs is a good idea, and I suggested it earlier, but you need two...
  3. KrisBlueNZ

    Piezo trigger circuit

    AFAIK he wants to simulate pressing the letter K when the piezo detects vibration. This could be done by hacking a reed relay contact across the pushbutton contacts for the K key on the keyboard. But the criteria for activating the relay are not clearly defined.
  4. KrisBlueNZ

    does this seem right?

    No, delaying the change in direction won't prevent the shoot-through. It occurs because the gates of the MOSFETs are connected together. It's the same problem you get in CMOS gates. See https://en.wikipedia.org/wiki/CMOS#Dynamic_Dissipation in the sub-section titled "Short circuit power...
  5. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    Connect the resistor between the positive rail and the top of the primary. So the bottom of the primary connects directly to the collector of the transistor. Then connect the probes to the two ends of the resistor. Yes you should check for common-mode noise. That's what you're trying to...
  6. KrisBlueNZ

    12V - 300V with Royer Oscillator

    I answered that. You are going about this the wrong way. You do not just find some core that you have laying around and try to make it work. You design the inductor for the requirements you need - which includes saturation characteristics, then you buy the core you want. This is especially...
  7. KrisBlueNZ

    2 stage op amp question

    Yes, an NMOS current mirror works pretty much like an NPN current mirror except with no gate current. The VGS(th) voltage of a MOSFET is typically more than 1V, so the input side of a MOSFET-based current mirror generally drops more voltage than a BJT-based current mirror, but they work in a...
  8. KrisBlueNZ

    LDR controlled Lamp from a 220VAC

    Right, as Gryd3 says, you need a connection from your drive circuit (which is isolated by TR1) to the triac. Otherwise there is no path for the gate current to return through. In other words, MT1 of the triac should be connected to your control circuit's 0V rail. You need some circuitry in...
  9. KrisBlueNZ

    Will an AOC - 23.6" LED HD Monitor work with my OLD PC?

    As far as I can tell, yes. I could be wrong. Don't try to sue me if it doesn't work out. You are ultimately responsible for your decision.
  10. KrisBlueNZ

    Dynex DX-L42-10A Intermittent Issues

    OK. 3V on pin 13 means the rest of the set is telling the power supply to start up. And 3.24V on V505 means the crowbar isn't activating, so the set should start up. This should cause the supply voltage to appear between pins 2 and 4 of N502. So if you have that 23V between pins 2 and 4 of...
  11. KrisBlueNZ

    attenuators

    What do you mean by "general" use of attenuators? To attenuate signals? Audio? RF? To attenuate DC voltages? To attenuate ripple in a power supply? There is no such thing as "general" use of attenuators.
  12. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    Do the test I suggested where you connect the scope probe to the earth clip, to see whether there is common mode noise. I'm pretty sure there will be. Then you can try different ways to avoid it, and repeat the test to see how successful they are. Using an SLA battery may help. Also be aware...
  13. KrisBlueNZ

    attenuators

    That depends on the definitions you use. But it is a good way to remove ripple in a power supply.
  14. KrisBlueNZ

    LDR controlled Lamp from a 220VAC

    Right, you wouldn't normally control a 220VAC lamp with a transistor. Triacs are normally used to switch mains loads. You should be able to buy a night light controller a lot cheaper than you can build one.
  15. KrisBlueNZ

    attenuators

    A regulator is normally the best way!
  16. KrisBlueNZ

    attenuators

    Hi David and welcome to Electronics Point :-) You need to tell us the context for your question. Are you talking about removing ripple in a power supply? Or some other kind of attenuation? And can you post schematics of the circuits you're talking about?
  17. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    Yes, sorry, I meant post #86. Yes, I don't believe the current is constant. I just think you need a better method of measuring it. Either the method you used in post #86 to get the ramp, or the method I just described in post #98. If we're lucky, using the method in post #98 we can avoid the...
  18. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    The current ramp shows pretty clearly in the first photo in post #87. If you want a better result using the two probe method, you could connect the resistor at the top end of the primary, instead of the bottom end, and use AC coupling on the inputs. This will allow you to increase the gain of...
  19. KrisBlueNZ

    12V - 300V with Royer Oscillator

    The Royer oscillator is a full wave forward converter. You should use a bridge rectifier at the output. That will change something - either both transistors will get hot, or both will run cool! I don't think the Royer oscillator is very suitable as a CDI driver. It works best working into a...
  20. KrisBlueNZ

    US based PCB manufacturer

    Do you mean 6~9 days?
Top