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  1. KrisBlueNZ

    Switching Regulator IC with Voltage Controlled Output

    I had attached it, and inlined it, and it was showing up for me. But there was no thumbnail at the bottom of the post. So I re-uploaded it. I hope it's visible now.
  2. KrisBlueNZ

    Switching Regulator IC with Voltage Controlled Output

    What output voltage range do you need? If you don't need a very wide range, you can use this trick. This diagram is part of a battery charger I designed. The LM2676S (U10) is used as a buck regulator with its output voltage controlled by the MCU via Q11 and Q10. This circuit has an output...
  3. KrisBlueNZ

    Electronic whack-a-mole

    LOL :-) Actually I'm having enough trouble designing it with CMOS! Re mahogany base, somehow I don't think a whack-a-mole game really deserves that kind of treatment!
  4. KrisBlueNZ

    Electronic whack-a-mole

    LOL Chris :-) Yes I've been thinking about a discrete design. I'm sure you'd like to see a design that uses just resistors and Darlingtons, or something like that, but the design I'm working on uses CMOS MSI. Sorry to disappoint you! No promises, but if I can get something that I think should...
  5. KrisBlueNZ

    Dimmer circuit help

    Not without details of your application. You can choose one - go for one that's cheap, a good fit mechanically, and will work from the supply voltage that you have available.
  6. KrisBlueNZ

    switch relay from transistor

    Yes, that circuit looks good and should work. The diode across the "coil" is only needed if the relay is the electromechanical type, which contains an actual coil, which exhibits inductance and will produce a "back EMF" when the current is interrupted. In this case, the diode bypasses the back...
  7. KrisBlueNZ

    Voltage Drop

    I'm not sure if this will help, but I have created an analogy for voltage, current and resistance that may help you understand their interrelationship more intuitively. https://www.electronicspoint.com/newbie-questions-t248766.html#post1470672 This analogy is NOT compatible with the traditional...
  8. KrisBlueNZ

    Dimmer circuit help

    Yes... replace it with a Hall effect sensor!
  9. KrisBlueNZ

    Computer Power Unit Failure

    What kind of cutout was it that tripped? Was it a standard circuit breaker that trips on overcurrent, or was it a "residual current device", aka "earth leakage circuit breaker", "earth fault cutout", "current imbalance detector" etc? If it's the latter, there may not be short circuit in the...
  10. KrisBlueNZ

    Including my PayPal information in my profile

    Just to repeat, the whole "for a fee" idea is NOT what I suggested, and NOT what I intended. The voluntary contribution tip jar concept is what I have been suggesting.
  11. KrisBlueNZ

    switch relay from transistor

    Hi scmojks and welcome to the forums. You can do this easily. Replace the 2.2k resistor and the LED in the diagram you posted, with the "coil" (it's not really a coil) of the solid state relay. You don't need to limit the current; it will be limited by the input resistance of the SSR. The...
  12. KrisBlueNZ

    is there a such thing as a "variable relay"

    I agree completely with BobK. Using an active device in its linear region is a crazy way to control a lighting load that's running from AC and I doubt it has ever been done like that. The AC waveform gives you a perfect opportunity to use PWM, effectively, by turning the triac ON at a specific...
  13. KrisBlueNZ

    Including my PayPal information in my profile

    KJ6EAD, I think the "tip jar for every account" is an excellent idea. That is the nature of the system I am proposing; I have no intention of making my help contingent on a payment, or even a donation, and I would not specify, or even suggest, the amount of the donation. I was thinking of...
  14. KrisBlueNZ

    Including my PayPal information in my profile

    OK thanks Steve. I'm happy to have this public; other members may also be interested. I don't mind about people not understanding the value of what I do. I'm not trying to start a commercial venture; just giving people the opportunity to "express their appreciation in a tangible form", if you...
  15. KrisBlueNZ

    Including my PayPal information in my profile

    Hi all, and especially moderators. I try to help out quite a bit on the forums, and I spend a significant amount of time drawing up schematics for users. Some of my friends have suggested that I should receive some payment for the support I give. I don't want to (and in any case wouldn't be...
  16. KrisBlueNZ

    Need Help with needed circuit

    I wouldn't use a PCB for such a simple circuit unless you want to do a production run. For simple projects like this, stripboard is ideal. If you're in England, it's called Veroboard. You can get it from Mouser (see...
  17. KrisBlueNZ

    PCB needs repairs

    Excellent!
  18. KrisBlueNZ

    Need Help with needed circuit

    Oops! The relay I specified has commoned coils. Luckily I can just change the circuit slightly and you won't have to get any new components. Here's the corrected circuit.
  19. KrisBlueNZ

    PCB needs repairs

    It seems the problem was a break between the relay pin (point D) and the big resistor (point E). It's hard to be sure exactly WHERE the problem is. My guess is that it's the relay pin, and you probably pulled the through-hole collar out of the board when you removed the relay. If the board...
  20. KrisBlueNZ

    How does this circuit work?

    My fingers are crossed too :-)
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