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  1. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    The diagram in the PDF is incomplete - it's too wide for the page. The P-channel MOSFETs are activated by a LOW voltage on their gates, so the inputs to the driver IC are active-high, not active-low. My suggestion about marking the signal states was simply to note "3.3V = enable, 0V = disable"...
  2. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    If you're talking about the switching time test circuit, this is not an application suggestion; it's the test setup for measuring the device's performance operating into a capacitive load. (A MOSFET gate is a capacitive load.) So they don't intend you to use a 470 pF capacitor in a practical...
  3. KrisBlueNZ

    Quick transformer question

    Perhaps the "12VAC" transformer he's using is specified as 12VAC at full rated load current, and its output voltage will be higher with no load or a lesser load. I thought there wouldn't be an issue going from 100 to 120V. I stand corrected. Thanks John.
  4. KrisBlueNZ

    Samsung 26in LCD TV Strobing / Flickering on and off, help!

    You can buy "rapid freeze" spray. It comes with a long nozzle that you can use to freeze components almost one-at-a-time. If you find that spraying almost anywhere causes the fault to disappear for a while, try to find the most sensitive area - the area that responds most quickly to the spray...
  5. KrisBlueNZ

    Transistor Mosfet pairs to drive LED cube layers

    That's looking pretty good. I have some suggestions. 1. Your circuit should define the active and inactive states for input signals. For example, "3.3V = enable; 0V = disable" (or the other way round; I'm not sure). 2. Re the decoupling cap across the IC, yes it's needed; the data sheet...
  6. KrisBlueNZ

    Quick transformer question

    Your 100V transformer will be fine. Edit: If you're worried, measure the AC voltage coming out of the transformer and make sure it's not more than 15V. Upload the schematic of the kitset circuit and we can tell you how critical the voltage will be.
  7. KrisBlueNZ

    Comparator inputs

    Ah. I hadn't thought of that. You're right. My series connection of the unsmoothed signals would cause a problem if the CTs are monitoring currents from different sources. The solution would be to smooth them independently before subtracting one from the other. That's probably what Duke...
  8. KrisBlueNZ

    Dual Slope ADC

    That's a point you didn't mention. The Wikipedia page has links and references. At the end. Look for distinctive keywords on the Wikipedia page then feed them into Google.
  9. KrisBlueNZ

    Which switch do I need? - just need a bit more info

    A careful reading of those sentences shows that you need a DPDT switch. These have six terminals, which you need to wire as follows. +12V-------------------o . o to circuit B <--------o . o---------> to circuit A . . . . . . . . . . . . . o . o-----------------+5V As CocaCola suggested, you...
  10. KrisBlueNZ

    Dual Slope ADC

    There's this amazing new site on the net that tells you all about stuff. It's called Wikipedia. http://en.wikipedia.org/wiki/Integrating_ADC
  11. KrisBlueNZ

    What did I do wrong?

    That circuit should have a resistor in series with the base of Q1. Otherwise Q1 can easily be damaged if the load current exceeds the limit even briefly. I suggest 1~10k. As others have said, you need a 5k trimpot for the voltage adjustment. You should not connect this circuit directly across...
  12. KrisBlueNZ

    Samsung 26in LCD TV Strobing / Flickering on and off, help!

    Have you checked for dry solder joints on the underside of the power supply PCB? At the same time, you can check for board discolouration that would indicate overheated component(s), and temporarily remove any medium-sized electrolytic capacitors to measure them and/or see whether they seem...
  13. KrisBlueNZ

    LM2917 Speed Switch Help!!! PLEASE!!!

    Can you post a complete schematic of what you're testing at the moment? Are you still using the LM2917 that may have been damaged?
  14. KrisBlueNZ

    Replacing Bus Power with an alternative .

    The USB supply voltage is nominally 5V. The outer two pins on the connector are used. One is +5V and the other is 0V/ground; this one will have continuity to the large copper areas on the board. You could power your circuit from a 5V USB phone charger, or a linear power supply using a 7805...
  15. KrisBlueNZ

    Op Amp - what am I missing

    Your last circuit has no DC path for the non-inverting input. The design in your first post should be fine if you fix the bias on the non-inverting (+) input; connect it to a voltage divider made from two equal resistors (e.g. 10k each) connected between +V and 0V. The op-amp's power...
  16. KrisBlueNZ

    Newbie question - building a locking circuit

    If you just want something that looks unique, you don't actually need to measure all the characteristics of the key material. You could use some conventional system to provide the actual key validation to control the lock, in conjunction with any kind of unique-looking material for the wow...
  17. KrisBlueNZ

    Want to build a 2 event delay timer controller

    Yes, you can just change C2. The suggested value, 15 uF (microfarads), gives a range of roughly 0.4~2.0 seconds; the timing range is proportional to the value. So if you change C2 to, for example, 2.2 uF, the timing range will change by factor of 15/2.2 as well, which will be 0.06~0.3 seconds.
  18. KrisBlueNZ

    Comparator inputs

    EinarA, thanks for that thorough response. I'm trying to understand it (it's Friday night so it might take a while :-) One thing I noticed: you said the "favor" control should have a zero point; if it should, it would be mid-way because either phase needs to be able to be favored. That's how...
  19. KrisBlueNZ

    ad 620 instrumentation amplifier

    So it's OK with a function generator but not with the "vibration analyzer or sensor"? What can you tell us about this analyzer/sensor? That description by itself doesn't tell us much. Do you have a manufacturer, part number? Link to a data sheet? List of basic specifications? What is it...
  20. KrisBlueNZ

    Replacing Bus Power with an alternative .

    What kind of bus is it? The PCI bus is documented at http://en.wikipedia.org/wiki/Conventional_PCI The ISA bus is documented at http://en.wikipedia.org/wiki/Industry_Standard_Architecture Find the power rails on the bus and see which ones are used by the amplifier section. You will need to...
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