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  1. KrisBlueNZ

    Common Emitter Transistor

    Your circuit already works and does what you want, doesn't it? What are you trying to change? Why? Is this a homework question? At present, the transistor is being used as an emitter follower, aka common collector configuration. It amplifies current (the op-amp output can only supply, say, 20...
  2. KrisBlueNZ

    The newbie's secret circuits circus

    A problem with some posters is that they really find it hard to express themselves clearly. Often this is partly because English is not their first language, but in most cases there seems to be a general lack of ability to THINK clearly. If the thought is not clear in the first place, there is...
  3. KrisBlueNZ

    SPI Chip Select Interference

    I forgot to mention, and it may not be obvious, that if you use an interrupt to periodically read the ADC or write the DAC, your Flash access code must run with interrupts enabled, or at least "sniff" for interrupts periodically (though this will introduce timing jitter - though timing jitter...
  4. KrisBlueNZ

    8550\8050 v's 2N3904/2N3906

    TedA: Snap!
  5. KrisBlueNZ

    8550\8050 v's 2N3904/2N3906

    A 555 won't operate at 1.5V. Its specified minimum operating voltage is 4.5V. It will run at less than that, but not as low as 1.5V. Besides, there's very little point adding a two-transistor buffer on the output of the 555 because it already has quite a high drive capability. In the low state...
  6. KrisBlueNZ

    Frequency Multiplier

    As well as answering Steve's questions, could you please answer the questions from my post that you didn't answer before. Thanks.
  7. KrisBlueNZ

    Charging Supercapacitor

    And an ESR of 0.9 milliohms! And I used to think that 4000 uF at 60V made a big bang :-)
  8. KrisBlueNZ

    SPI Chip Select Interference

    Have you considered that the problem may not be electrical interference between the SPI chip select signal and the audio circuitry, but may be due to the Flash memory accesses disrupting the timing of the sampling used for recordng and/or playback? If scheduled sample times are missed, either...
  9. KrisBlueNZ

    Electromagnetic Induction

    This fallacy seems to be popular with "over-unity" folks as well. You're talking about converting energy in the form of motion and force into electrical energy. There is a very limited amount of energy available; whether you convert small amounts of it separately and add them together, or...
  10. KrisBlueNZ

    The newbie's secret circuits circus

    donkey, agreed 100%. Good suggestions there. I just LOVE threads with a title of "advice needed" or "electronics question". Re "what is wrong with my code?" you could always point them to this answer or suggest that they ask this expert.
  11. KrisBlueNZ

    12V Relay from a .2mA LED

    OK, here's a preliminary schematic to give you an idea of what you'll need. "LEDX" is the "HOT" LED in the urn. You say you've already wired to it. It feeds into the circuit on CN1 and CN2 (you need to get the polarity right) and when the LED is ON, it energises the LED in U1 which is an...
  12. KrisBlueNZ

    12V Relay from a .2mA LED

    If you want to avoid modifying the urn, you can probably use an LDR (light dependent resistor) to "watch" the LED (would have to be stuck to the side of the urn and enclosed to prevent it responding to ambient light). It could drive a MOSFET or Darlington pair that would drive the relay for the...
  13. KrisBlueNZ

    Need help getting LCD panel to work

    That looks good to me, but the only way to be sure is to try it. As CocaCola said, you can do it with solder. You may need to remove the "wings" from the crimp pin to make it fit into the hole in the housing. Cool! For Go for 1K resistance, if you can get it. Any value up to 10K will be fine...
  14. KrisBlueNZ

    Charging Supercapacitor

    The rate at which energy can be put into a capacitor or supercapacitor is directly proportional to the current that you can feed into it. If you have a higher voltage at a low current, you could use a switching power supply to step the voltage down and in the process, step the current up. But...
  15. KrisBlueNZ

    Electromagnetic Induction

    Good advice from Steve, as usual. Most importantly, I don't believe you'll get any useful amount of power. You can get significant power from tidal energy, but something bobbing on the waves can only generate a tiny amount of power. Enough to power a device that's designed with a very low power...
  16. KrisBlueNZ

    12V Relay from a .2mA LED

    Welcome to the forums :-) "an LED circuit"? Could you be more specific? Do you have any power source available? Can you give a much more thorough description of your problem?
  17. KrisBlueNZ

    The newbie's secret circuits circus

    http://catb.org/esr/faqs/smart-questions.html This is a good article written by Eric Raymond. It was linked from a thread on LinkedIn where the same problem was being discussed. Unfortunately the article is probably much too long for lazy people and/or those with poor English language skills...
  18. KrisBlueNZ

    Frequency Multiplier

    The voltage is a separate issue; it's not hard to convert a 0V/8V swing to a lower voltage (a voltage divider with two resistors) and it's not hard to convert a lower voltage swing to a 0V/8V swing (a transistor or signal MOSFET with a pullup resistor to the 8V supply). Is the 8V supply (or some...
  19. KrisBlueNZ

    Young jedi needs pcb/switch type assistance!

    You might want to check that the switch is a shorting type. If it's a non-shorting switch, as it moves between positions the inverter will be working with no load. While it probably won't damage the inverter (though it may not be designed to run without a load), the voltage is bound to increase...
  20. KrisBlueNZ

    Frequency Multiplier

    Yes, I suggested that in my first post. Yes, there is no perfect solution. Converting the PWM signal to a voltage then regenerating the PWM at a higher frequency will have lag and won't be mathematically exact, so it may or may not be usable, depending on the details of the application. That's...
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