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  1. KrisBlueNZ

    Attempting to get volt/octave response in Tube VCO

    If the VCO already has an exponential response to the control voltage at the 6SN7's grids, which I doubt, then all you need is to scale the control voltage so that a 1V change will cause a factor of 2 change in frequency. Do you have a frequency counter or some other way to measure frequency...
  2. KrisBlueNZ

    What exactly Is voltage drop and how Is It detected?

    What I said was that a current source can be made with a resistor in series with a battery. This circuit has two output terminals and if you connect a load across them, current will flow through it. A circuit consisting of a resistor connected across a battery also has two connection points...
  3. KrisBlueNZ

    SMPS's with cascoded opto feedback

    That explains it nicely. If a document refers to the collector output topology as "common emitter" and the emitter output topology as "common collector" or "emitter follower", it's because the author hasn't realised that those names they aren't appropriate, or the author is using them as...
  4. KrisBlueNZ

    Converter Circuit

    Thanks Bob. I was hoping my answer would make him think again. (Or think for the first time, perhaps.)
  5. KrisBlueNZ

    SMPS's with cascoded opto feedback

    You can connect it with the emitter to 0V and the collector through a resistor to V+ or you can swap the transistor and the resistor over; this will determine whether the voltage goes high or low when the optocoupler is energised, but the transistor doesn't (can't possibly) behave any...
  6. KrisBlueNZ

    Converter Circuit

    Congratulations! You explained your project, and it only took 10 posts for us to get that information out of you! So you have a current transformer that gives an output of 333 mV RMS maximum as a 50 Hz sinewave, and you want to feed this into the current input of an energy meter that expects 5A...
  7. KrisBlueNZ

    Help Needed with SCR and Optocoupler

    Yeah this circuit is VERY dangerous! adamq, I guess you know that the electrolytics need to be specified for photo flash use? Standard electrolytics will fail in this application because of the extremely high currents and fast discharge.
  8. KrisBlueNZ

    Repairing power supply of Ogawa Reflexology

    I agree with Adam. It looks like a Polyswitch resettable (PTC) fuse.
  9. KrisBlueNZ

    SMPS's with cascoded opto feedback

    How can a transistor whose base is not connected to anything be said to be operated in common emitter or emitter follower configuration?
  10. KrisBlueNZ

    Help Needed with SCR and Optocoupler

    Well, I don't have a lot of experience with this kind of application, so I could be overlooking something here, but I think that once the SCR fires, its anode, gate, and cathode will all be within a volt or two of each other, and no significant current will flow in the output circuit of the...
  11. KrisBlueNZ

    What exactly Is voltage drop and how Is It detected?

    Yes. Say we have a 9V battery (let's assume it's a perfect voltage source) with a 100k (kilohm) resistor connected across it. The current that will flow through the resistor can be calculated using Ohm's Law: I = V / R where V is 9V and R is 100,000 ohms. 9 / 100,000 is 0.00009 amps, or 90...
  12. KrisBlueNZ

    What exactly Is voltage drop and how Is It detected?

    Hi Reprovo and welcome to Electronics Point :-) A similar question was asked in this thread: https://www.electronicspoint.com/newbie-questions-t248766.html As folks have already said, voltage "drop" is a difference in voltage between two points, due to current flow through a non-zero...
  13. KrisBlueNZ

    electronics solder

    AFAIK, "Multicore" solder just has multiple cores of flux inside it. That description doesn't tell you what metals it contains, or the percentages of each. That information should also be marked somewhere on the roll.
  14. KrisBlueNZ

    Building a 3.5mm Switch with 4 inputs

    The instructable uses a 3PDT switch. That's three pole, double throw. Each pole switches one connection. You need three poles because you want to switch all three connections on the jack socket - tip (left channel audio), ring (right channel audio) and sleeve (ground). The number of "throws"...
  15. KrisBlueNZ

    Converter Circuit

    Not enough information. What frequency is the AC? What waveshape? What power source do you have? What kind of load do you need to drive? What is the load resistance? What is the purpose of the project?
  16. KrisBlueNZ

    Converter Circuit

    TELL. US. EXACTLY. WHAT. YOU. WANT. TO. DO.
  17. KrisBlueNZ

    Attempting to get volt/octave response in Tube VCO

    I'm not sure how your circuit will behave. I can see that when the opposite triode turns ON, the falling anode voltage will be coupled through the capacitor to the grid and the grid will try to go negative, but will be prevented (or at least hampered) by the cathode follower driving the grid...
  18. KrisBlueNZ

    Attempting to get volt/octave response in Tube VCO

    You've shown the right hand capacitor connected to the wrong end of the right hand anode resistor. I have to ask why you want to use valves (toobs) to produce squarewaves. If it's a gimmick, fine, but be aware that a squarewave from a toob multivibrator will not have "the toob sound". If that's...
  19. KrisBlueNZ

    Advent TV

    Yes, and it could be a lot of things, not necessarily the line output stage. It could even be an IC in the signal processing chain. To the OP, there are a few things you can check for easily. Can you hear the squeal from the line stage when the set is running? If not, ask a child; they have...
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