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  1. KrisBlueNZ

    Simple Arduino question

    Your simplest option is to use a small relay such as a reed relay. Here are some suitable options: Reed relay; coil 5V 5 mA (can probably be driven directly from the Arduino, but still needs a reverse diode): http://www.digikey.com/product-detail/en/9007-05-40/306-1251-ND/710440 USD 1.63 Reed...
  2. KrisBlueNZ

    Simple Arduino question

    You don't need an Arduino to generate a stream of pulses - a 555 oscillator will do fine and you can find circuits all over the net. Do you know the nature of the rotation pickup device? If it's a Hall sensor, or unknown, it's probably simplest to activate it with an electromagnet. A 555 can...
  3. KrisBlueNZ

    voltage "clamp" when input analog signal removed

    Sorry about the slow response. This issue is becoming a bit complicated. So the motor controller is a Midwest Motion Products MMP 25A? The one described at http://www.midwestmotion.com/products/speedcontrols/25A-24V.html You mentioned the Delta Motion RMC75E. This is documented at...
  4. KrisBlueNZ

    PCB Layout Help

    What is the manufacturer and the complete part number for the 25 MHz crystal you're using? Have you tried another crystal? Either the same manufacturer and part number, or different? Or are you still using the first crystal you've tried? Have you tried more than one board? Are you putting your...
  5. KrisBlueNZ

    sampling communication lines without interfering the signal

    As long as the data line voltages are within the Arduino's power rails, and the I/O connections go straight to the AVR pins with no other components involved, connecting the Arduino to the data lines shouldn't cause a problem. It will add a little bit of capacitance but that should be all. Make...
  6. KrisBlueNZ

    Simple Voltage Regulator and Wiring Question

    Hi there and welcome to Electronics Point :) As Steve says, you NEED to connect the ground pin. The regulator regulates the voltage between the OUT pin and the GND pin. With the GND pin not connected, it couldn't tell what its output voltage was! (There are other reasons why the GND pin must be...
  7. KrisBlueNZ

    Integrator circuit using single resistor gain"ad620" op amp?

    Guys, look up the Wikipedia article on Rogowski coils. I think he intends to use the integrator as an actual integrator rather than a kind of filter.
  8. KrisBlueNZ

    TRIAC Switching Circuit

    A saturated switch should be common emitter, but a transistor current booster for driving LEDs, motors, relay coils, buzzers or whatever doesn't need to be a saturated switch, and an emitter follower will work, and may be appropriate, as long as the base-emitter voltage drop doesn't cause a...
  9. KrisBlueNZ

    Integrator circuit using single resistor gain"ad620" op amp?

    The frequency response of a standard op-amp integrator is set by the resistor and the capacitor. It is assumed that the op-amp has enough gain that errors due to gain are negligible. Using a differential amplifier with relatively low gain will affect the frequency response of the integrator but...
  10. KrisBlueNZ

    help virus problem

    When "antivirus" software reports huge numbers of detections, it MAY be that the antivirus software itself is a trojan horse and the virus hits are false. This is definitely the case if the "antivirus" software offers to remove the viruses in exchange for a fee paid via Western Union or bitcoin...
  11. KrisBlueNZ

    Integrator circuit using single resistor gain"ad620" op amp?

    Hi and welcome to Electronics Point :-) Yes I think you can, but why would you? There's no advantage; only disadvantages, including the increased cost. The AD620 is just a differential amplifier with programmable gain. The op-amp integrator circuit requires a differential amplifier with high...
  12. KrisBlueNZ

    TRIAC Switching Circuit

    You CAN connect the transistor that way - it's called the "common collector" or "emitter follower" configuration. You don't need R1, and you don't need R2. Just connect the MCU output directly to the base of the transistor. Actually, you mustn't have either of them - they reduce the voltage at...
  13. KrisBlueNZ

    Important capacitor specs ?

  14. KrisBlueNZ

    Car steering effort adjusting

    Hello and welcome to Electronics Point. Unfortunately, functional modifications to vehicles are potentially very dangerous. Electronics Point's policy is to disallow discussion of such subjects to protect all of the members involved. I have closed this thread.
  15. KrisBlueNZ

    Important capacitor specs ?

    Yes, but the ripple current specification is irrelevant for caps on the output of a linear regulator. Thanks for the info Steve. I stand corrected!
  16. KrisBlueNZ

    Slow down this circuit's oscillation

    No need to upload a corrected version mate :-) It does look a bit odd, but I couldn't say whether it's right or wrong.
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