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  1. KrisBlueNZ

    Help Getting Started with PIC Microcontrollers

    I wish they would include the core type on the selection guide. Baseline, mid-range, enhanced mid-range, high end. Or just the instruction word size.
  2. KrisBlueNZ

    Confusing Relay-Relay Connection .. pls help

    Good. So you need to connect your 1N4002 or 1N4007 across the coil pins, in the opposite direction to the LED inside the relay. So everything is working now?
  3. KrisBlueNZ

    Ultrasonics

    A 1000 foot house? And in any case, ultrasonic "pest repellers" have never been demonstrated to be effective and are generally considered useless.
  4. KrisBlueNZ

    Help Getting Started with PIC Microcontrollers

    Yes, you can do that. There are several ways. If the frequency you want to measure is high, you can use it to clock a counter and use a second counter as a time reference to measure the intervals between when the first counter wraps around. If the frequency you want to measure is low, you can...
  5. KrisBlueNZ

    Triggering a 555 timer on opening of a line

    It looks like pin 1 is the +24V output to the external loop, pin 2 is the detection input, and pins 3 and 4 are just connected together internally. But it can't be that simple. That wouldn't allow the laser to detect the two circuits independently and require the second one to be broken...
  6. KrisBlueNZ

    Triggering a 555 timer on opening of a line

    It's not a "0V line"; it just reads 0V when there is no connection from that pin to the other pin that provides the +24V. It's the input to the laser. Right. So the laser provides +24V on pin 1 and monitors the voltage on pin 4. There will be a pulldown resistor or something similar inside the...
  7. KrisBlueNZ

    checking if capacitor is burned out

    If you measure a capacitor with an ohmmeter, you should measure open circuit. With small capacitors (1 µF or less) the meter should indicate open circuit immediately; with larger capacitors (say 100 µF and higher) it may take a few seconds or minutes for the meter to read open circuit, as the...
  8. KrisBlueNZ

    getting error on negative clipping

    The 0.7V you're seeing is not an "error"; it's simply the forward voltage of the diode. A diode does not clip perfectly; as well as the forward voltage, there's the effective resistance. But you can reduce the voltage offset by connecting the diode's cathode to a voltage source of -0.7V...
  9. KrisBlueNZ

    Driving many LEDs with a Single Arduino Uno?

    Normally you would wire LEDs in series strings, and put the strings in parallel, and use a higher voltage, e.g. 12V. But you can't do that with RGB LEDs unless they have six pins, i.e. you can get access to both ends of each LED independently. RGB LEDs normally have four pins - one pin for each...
  10. KrisBlueNZ

    Triggering a 555 timer on opening of a line

    OK, I think I'm getting the hang of it now. Correct me where I go wrong. The laser uses four pins on its serial connector to detect external events that require the laser to shut down, for safety. For the laser to run, an external circuit must provide continuity between pin 1 and pin 4, and...
  11. KrisBlueNZ

    Sony CX350 CD Changer

    Good idea. I'll start something in the Resources section.
  12. KrisBlueNZ

    DS1307 initializing

    I think the problem may be that you're not masking off the CH bit, bit 7 of the seconds register. The data sheet is not clear on what this bit does, but it seems it's set on startup. To ignore this bit, you need to change the line in read_DS1307() that reads seconds = I2C1_Rd(1); to...
  13. KrisBlueNZ

    Triggering a 555 timer on opening of a line

    I'm afraid that doesn't really help me understand what you have there. So you have two independent 24V DC sources? And they are joined together, positive to positive and negative to negative, on a "serial interface" connector? Does this connector carry power and serial data? What does it...
  14. KrisBlueNZ

    Sony CX350 CD Changer

    I found the service manual on http://www.elektrotanya.com. This is an excellent site for finding service manuals and technical information. Page 63 shows one belt, reference 159, part number 4-219-326-01, description "BELT (DIA. 42X1.2)". Page 64 shows two belts, reference 206, part number...
  15. KrisBlueNZ

    Turns on LED upon receiving IR signal

    I don't think induction would be practical because of the distance involved. Yes it might be a practical way to transmit a signal, but not enough power to light an LED.
  16. KrisBlueNZ

    Confusing Relay-Relay Connection .. pls help

    As long as the diode is new and is reliably connected across the coil, you should be fine. If you really want to test it, you could connect an LED across the relay coil with the same polarity as the diode. That is, anode to negative and cathode to positive. Then activate an alarm to close the...
  17. KrisBlueNZ

    Ultrasonics

    I would say not, though I can't show you any calculations to prove it. My reasons are (a) vibrations in air are absorbed and decay quite rapidly; (b) higher frequencies decay more rapidly than lower frequencies - because of the inertia of the atoms and molecules in the air, I guess; (c)...
  18. KrisBlueNZ

    voltage "clamp" when input analog signal removed

    A bit of Googling turned up these possibilities. They are all free. ProfiCAD: http://www.proficad.com/ - looks ideal. The "home license" version is free, and has some fairly minor restrictions. Google/Trimble Sketchup: http://sketchup.google.com/intl/en/product/gsu.html - easy to use; many...
  19. KrisBlueNZ

    capacitor replacement

    Come on Harald, you don't want us to send you a lmgtfy link do you? To jump the gun is to "act before the proper or appropriate time". I guess it comes from the starting gun in a race. If you start running before the gun is fired, you would be "jumping the gun".
  20. KrisBlueNZ

    Level signal compatibility?

    Logic probes designed for TTL/LS used those same levels - 2.4V and 0.8V. Some logic probes had a switch to select between TTL/LS and CMOS thresholds. When feeding a signal from TTL/LS to CMOS in a fully 5V system, a pullup resistor (typically a few kilohms) is used to pull the TTL/LS output...
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