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  1. KrisBlueNZ

    Want to build a 2 event delay timer controller

    A resistance of "2K2" is 2.2 kilohms, which is 2200 ohms. The "k" takes the place of the decimal point. R1 and R2 are the stopper resistors for the two timing circuits. You can change the values of R1 and VR1, and R2 and VR2, to vary the adjustment range, but don't reduce R1 or R2 below 1k...
  2. KrisBlueNZ

    SMPS Build...

    Wow, that is an impressive component! The general connection of a linear regulator with voltage feedback is shown here: en.wikipedia.org/wiki/Voltage_regulator#Regulator_with_an_operational_amplifier This is a voltage regulator only; it has no current limiting. Current limiting can be added...
  3. KrisBlueNZ

    Simple Phototransistor switch circuit

    As you asked for it, here's a reasonably clean design, I think. Regarding hysteresis. If you're working with any quantity that represents a physical variable, i.e. light intensity at a particular location in this case, and you're driving an interrupt-capable input, you want hysteresis. Trust...
  4. KrisBlueNZ

    What is this component?

    Hey everyone! I've figured out chucky's true identity!
  5. KrisBlueNZ

    Resonance

    Electro132, I think you need to learn a great deal more before you will even be able formulate your questions in a meaningful way. You have consistently refused to explain the purpose of, and application for, your project. Harald is a valuable resource and you are wasting his time.
  6. KrisBlueNZ

    Touch switch help!

    Looks good, hcccs
  7. KrisBlueNZ

    Resonance

    This thread makes me think of Chopin's Minute Waltz. He was inspired to write it when he saw a dog chasing its tail. Electro132, it would really help if you EXPLAIN WHAT YOU WANT TO DO. Not the technical details of what you think you want, but the OVERALL AIM OF YOUR PROJECT. Include lots of...
  8. KrisBlueNZ

    Wire Jack Parallel With Speaker

    It depends on the quality of the speaker amplifier in the instrument. It could have crossover distortion, and possibly clipping I guess. It will also be high-pass filtered to remove the low frequencies that the internal speaker cannot reproduce. This filtering may be as simple as a capacitor...
  9. KrisBlueNZ

    Wire Jack Parallel With Speaker

    If it already had an output jack, I would try to fix that. It will have a nice clean signal. You can connect across the speaker, but the device you plug into it won't get the sound that you hear from the speaker. The sound of the internal speaker will be coloured because of the speaker size...
  10. KrisBlueNZ

    Touch switch help!

    The circuit with the JFET input looks good. Post the component values though, to be sure. If your original circuit wasn't sensitive enough, you could use a Darlington with higher gain, such as the MPSA14. The BD675A is a 4A type. An MPSA14 has at least ten times as much gain, and is still fine...
  11. KrisBlueNZ

    Comparator inputs

    OK. This business about the shunt resistor values being wrong seems odd. You know the current ratio of the CTs, and you know Ohm's Law, so you know what values should be needed. The calculations I used to work out a value of 270 ohms are in post #19 on this thread. A "fuzzy" appearance on an...
  12. KrisBlueNZ

    Simple Phototransistor switch circuit

    Use an SMT 555 (SO-8 package). That plus 2~3 passives should work out about the same size as one or two transistors and five-odd passives.
  13. KrisBlueNZ

    What is this component?

    Oh yeah...
  14. KrisBlueNZ

    Application of 7805

    Yes, a 470 ohm resistor should be enough load to prevent the output voltage from rising greatly when no load current is being drawn. You can check the output regulation by measuring the output voltage with no load (apart from the 470R resistor that's in the power supply itself), and measuring...
  15. KrisBlueNZ

    What is this component?

    __Hmm...__
  16. KrisBlueNZ

    Touch switch help!

    Try connecting the two touch pads together with a piece of wire. If the LED still doesn't light, there's something wrong with your circuit. Upload a photo of your construction. We may be able to see what's wrong with it.
  17. KrisBlueNZ

    sonar object sensor/ buzzer ciruit design

    I don't know much about it, I'm afraid. I have played around with ultrasonic movement detection using the Doppler effect but your requirement is different - you want proximity detection. I would start by Googling the important keywords...
  18. KrisBlueNZ

    SMPS Build...

    Bob, I'm not really sure what he wants to do, and I don't think he really knows either. medictrode, you know that feeding the output of a switching supply into the base of a transistor doesn't make that transistor switch? The output of a switching supply is DC. If you feed it into a transistor...
  19. KrisBlueNZ

    Trapezoidal Wave Generator Circuit

    You need to use a buffer between the output and the voltage divider. An emitter follower (Wikipedia it) would be enough, or you could use an op-amp. After that you'll have to feed it to an amplifier with an adjustable gain and an adjustable DC offset, as Harald suggested. This would normally...
  20. KrisBlueNZ

    SMPS Build...

    Wow! 50A collector current, 300W dissipation, perfect for a linear power supply. Make sure you can drive the base hard. Guaranteed current gain is only 15 at 10A collector current! Have a careful read of the data sheet - the VCEsat and leakage current and anything else unusual. Watch out for...
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