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  1. KrisBlueNZ

    IC heating up!!

    You still haven't given us a full and detailed introduction to your situation. In other words, tell us the FULL STORY. I can't ask the right questions because I don't know what to ask. You need to start from the beginning and explain the whole situation. I'll try one more time to work from your...
  2. KrisBlueNZ

    resistor question?

    Thanks Miguel for the clarification.
  3. KrisBlueNZ

    MOSFET power dissipation definition?

    Transistors, MOSFETs etc have a specificaiton for maximum power dissipation. It's normally in the "absolute maximums" section, early on in the data sheet. Exceeding this specification, even briefly, can result in the immediate loss of the Magic MOSFET Smoke (TM). This is the reason why you need...
  4. KrisBlueNZ

    help for lm324

    What BobK said. Also, the LM324 cannot compare voltages that are close to its positive supply rail. Inputs have to be at least 1.5~2.0V lower than the positive supply voltage (depending on manufacturer and temperature) for the LM324 to correctly compare the voltages.
  5. KrisBlueNZ

    Comparator for anemometer

    Here's my suggestion. The power supply for the op-amp is 6V. This can be increased for better performance. The op-amp inputs are biased at around half the supply voltage by R1 and R2. This is necessary to keep the op-amp in its operating region. Usually a decoupling capacitor is connected in...
  6. KrisBlueNZ

    Comparator for anemometer

    Are you aware you have positive feedback around the op-amp? A simple gain stage uses negative feedback, i.e. the feedback resistor, R2, and the input source, are connected to the inverting input ("-" symbol) and the non-inverting input ("+" symbol) is biased at some DC voltage in between the...
  7. KrisBlueNZ

    resistor question?

    Ohm should not be spelled with an initial capital unless you are specifically talking about Mr. Georg Simon Ohm, or his Law. It's correct to say that a resistor value is 10 ohms (without the capital O). When a unit is written as a single letter, the capital is used; for example, 10 µF...
  8. KrisBlueNZ

    IC heating up!!

    You say that, but you still haven't explained very much about the situation. Have you heard the lateral thinking exercise about the man who lives on the 12th floor of an apartment block, and takes the elevator every morning, but every evening, takes the elevator to the 10th floor and takes the...
  9. KrisBlueNZ

    IC heating up!!

    An input signal with a swing of 0V~7V will not reliably trigger a 40106 that's running from 12V. A simple voltage offset (which can be implemented with two resistors, or a zener diode and a resistor) could fix this, but whether it will work or not depends on the characteristics of the signal...
  10. KrisBlueNZ

    Design question on microcontroller and TIP122

    It's generally recommended that you put a small amount of resistance - something in the range of 10 ohms to 47 ohms - in series with a MOSFET gate. You may also want to put a resistor of, say, 10k between the MOSFET's gate and source, so that it turns off if the micro is not driving it (some...
  11. KrisBlueNZ

    need help with simple 3v to 34v transistor relay/switch

    If you have an interrupt source (e.g. a timer, or the USART) triggering an interrupt handler, and your mainline goes into a loop, the interrupts will continue to occur and be handled by the interrupt handler, unless you disable interrupts in the mainline. Interrupts such as the received...
  12. KrisBlueNZ

    need help with simple 3v to 34v transistor relay/switch

    That question doesn't make sense. Here's what your code needs to do to implement a delay in a thread: Read the timer 1 register and store it in a variable - e.g. thisthread_starttime; Set the state number appropriately so the next time this thread gets execution, it will start at the following...
  13. KrisBlueNZ

    need help with simple 3v to 34v transistor relay/switch

    You need to avoid delays as well. The code needs to be structured like my example, not like the code you posted. Using interrupts is sometimes essential, but in your case I don't think it will be. Using interrupts can introduce problems with resource ownership - an interrupt handler can change...
  14. KrisBlueNZ

    need help with simple 3v to 34v transistor relay/switch

    MUST loop? No. That's the problem. You can't write the code like that. Instead of writing delay(400), imagine how you would write code that can be called at any time and will test whether the delay in progress has expired. First of all, you will need a source of timing information that can be...
  15. KrisBlueNZ

    need help with simple 3v to 34v transistor relay/switch

    I've explained how to write functions that multi-task co-operatively. Re-read my example code and see how it is designed: as a self-contained function that can be (and must be) called repeatedly inside any loop in the mainline. Personally I would use this structure for EVERY parallel operation...
  16. KrisBlueNZ

    Please help understand this circuit .

    There are two almost identical transformers. I suspect this means there's a power factor correction stage in there too. An in-focus close-up of the underside, with the IC part numbers visible, would confirm this. Also it looks like there may be a daughter board. A close-up of that would help as...
  17. KrisBlueNZ

    Phase detect compare

    It's both. There's a spinning anemometer for measuring wind speed, and also a vane that measures wind direction. The "speed reed" switch is mounted in a fixed location, and just picks up the rotation of the anemometer, and I think that the "direction reed" switch is also actuated by the magnet...
  18. KrisBlueNZ

    Phase detect compare

    Here is a possible non-microcontroller solution. SW1 and SW2 are the two reed switches; let's say SW1 is the "speed reed" and SW2 is the "angle reed". When a reed switch closes, after a short time (determined by RSn and CDn, the debouncing components) the input of the relevant Schmitt trigger...
  19. KrisBlueNZ

    Phase detect compare

    Yes, debouncing is definitely needed. But I don't think connecting one switch to the clock, and one to the data input, will give any useful result. The idea I'm working on involves setting the flip-flop on the active-going edge from one reed switch, and clearing it on the active-going edge from...
  20. KrisBlueNZ

    need help with simple 3v to 34v transistor relay/switch

    Sorry, I can't suggest any explanation for that problem. I've never used PICs myself; I prefer AVRs for that sort of application. But CocaCola and other users have a lot of experience with PICs. Perhaps they can suggest something.
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