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  1. KrisBlueNZ

    Help repairing a 20-year-old driver board

    Yeah, probably silly :-) The voltage out of a battery is very clean. It's a dual H-bridge. I doubt that it drives the cubes, because there are lots of them, and the H-bridge's outputs can't be multiplexed in any clean or efficient way. I can't suggest what it might be used for, because I don't...
  2. KrisBlueNZ

    Bidirectional Data Line Circuitry

    Thanks Lee for that description. It really helps to have an idea what we're talking about! Do you intend to mechanically attach the cubes to each other? Or will you only use electromagnetism? Do you think it might be a good idea to do the communication electromagnetically as well? That would...
  3. KrisBlueNZ

    K2937

    http://documentation.renesas.com/doc/products/transistor/rej03g1051_2sk2937ds.pdf It has the same pinout as all of the MOSFETs I've ever seen in a TO-220 or TO-220-style package. Looking at the part number, with the legs pointing down, from left to right, gate, drain, source.
  4. KrisBlueNZ

    MIDI organ pedals

    Touch-sensitive music keyboards detect the force applied to each key by measuring the time delay between when the first contact closes, and when the second contact closes. The harder you hit a key, the faster the key will move. As the key comes down, it presses two blister-like bits of...
  5. KrisBlueNZ

    Bidirectional Data Line Circuitry

    I think it would really help us if you could be more specific and less abstract with your description. How about starting with an overview of the purpose of the project and then get to the details of how the component parts need to behave, and the meaning of the eight bits of data that they need...
  6. KrisBlueNZ

    Help repairing a 20-year-old driver board

    It's a bit hard to tell much from them. Try taking pictures outside on an overcast day, with no direct sunlight and no flash. This gives good all-round illumination. Sounds likely to me too. I've seen those. They're a clever idea. We have them to indicate route numbers and destinations on some...
  7. KrisBlueNZ

    BOSS DS-1 Pedal

    Another suggestion: is there any sign of any sort of goop on either side of the board? Perhaps something spilled on it, or some adhesive residue? Any dirt or impurities? If so, clean the board with isopropyl alcohol and a toothbrush and a cotton swab. If it's on the component side, you might...
  8. KrisBlueNZ

    Help repairing a 20-year-old driver board

    A few photos would be pretty helpful. Most of us have probably never seen inside a unit like this, and some photos would give us a general idea of what you're talking about. I think you're right that the LT1074 is used to regulate the 12V (or thereabouts) rail. The 110VAC goes through a...
  9. KrisBlueNZ

    BOSS DS-1 Pedal

    Hello there and welcome to Electronics Point :-) I agree with Adam that your description sounds like motorboating. It would be helpful for us to hear it though. Can you record a few seconds into your computer, convert to a mono MP3, ZIP it, and upload it here? To attach it to a post, use...
  10. KrisBlueNZ

    SMPS's with cascoded opto feedback

    Unless he agrees with us, in which case we'll accept his opinion as absolute, conclusive proof, right? :-)
  11. KrisBlueNZ

    Projects for Newbies

    Good, and good! :-)
  12. KrisBlueNZ

    Attempting to get volt/octave response in Tube VCO

    I don't know whether varying the screen grid voltage would vary the current linearly or not, but even if it did, I'm not sure that would help. If you're planning to replace the 12AU7 with pentodes, it won't help at all, since the current you need to vary is the current with which the capacitors...
  13. KrisBlueNZ

    Attempting to get volt/octave response in Tube VCO

    I've plotted the data you listed. Here's frequency vs. control voltage, plotted on two linear axes. The data sheet only gives you data for the toob under fixed conditions. In your circuit, the current is changing constantly as the anode voltage changes and as the capacitor charges up. The...
  14. KrisBlueNZ

    SMPS's with cascoded opto feedback

    How can there be more electrons flowing into the emitter than flowing out of the collector? Where do the extra electrons go? They can't travel to the LED, or out of the package, because the package is an insulator. And can you explain the difference between your claim that "with a photo...
  15. KrisBlueNZ

    Projects for Newbies

    That kit looks very good. My only concern is the soldering station. It looks like a Weller but at that price I think it must be a lookalike. Replacement Weller tips are readily available, but is it compatible with them? But even if it can't be maintained, you should get a few years' use from it...
  16. KrisBlueNZ

    bit shifting

    That doesn't do anything and will probably be optimised into nothing by the compiler. It's an EXPRESSION that evaluates to sPORTA.port shifted left by one bit. You have to assign it to something if you want to use it. What you want is sPORTA.port <<= 1.
  17. KrisBlueNZ

    SMPS's with cascoded opto feedback

    I meant to suggest that as a possible problem with your test circuit. An easy way around the whole matter is to use a 9V battery as the power source for the transistor circuit. Then the whole circuit is fully floating with no significant capacitance anywhere, and you can connect the scope...
  18. KrisBlueNZ

    Question About Relays

    A switch needs to be mechanically flipped by a person. A relay changes state in response to voltage across its coil, which can be controlled by a circuit. A common example is the relays used in washing machines to activate the pump and other heavy duty devices. These relays are controlled by...
  19. KrisBlueNZ

    Any analogy as to how decoupling works ?

    I created an analogy that explains capacitors and resistors fairly well. At least, I think it does. It's had a mixed reaction here and I'd like to get more feedback on it. I call it the DTS Model. There's an introduction at...
  20. KrisBlueNZ

    Transistor Question

    Steve, I don't think the CS9013 is a 2SC9013. According to the docs, the CS9012 is a PNP, and 2SC devices can't be PNP, so CS isn't an alias for 2SC. Also, I get a lot of hits for CS9012 and CS9013.
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