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  1. Alec_t

    Measure spindle speed with a Multimeter???

    LDRs are rather sluggish, so you would get unreliable results at high spindle speeds.
  2. Alec_t

    Automatic door

    Obviously health and safety issues are important here. Any motorised mechanism will need to be weak enough to avoid crush injuries and have no protruding/sharp portions.
  3. Alec_t

    Low cost electric skateboard?

    Do you really need to reverse the direction of travel? If not, you can eliminate the H-bridge and save a dollar :).
  4. Alec_t

    2 audio signals to a single fm transmitter

    Depends if the headphone output signals have a DC component. If they do, you may need to couple the two outputs to the Tx via respective capacitors.
  5. Alec_t

    Floating Dc Current Source

    What will power this current source? Is this for some medical purpose?
  6. Alec_t

    Diode for thermostat circuit

    What type of thermostat? Does it simply close a pair of contacts when heat is demanded, or does it incorporate some fancy electronics to provide a signal? Can you post a link to the thermostat spec/datasheet?
  7. Alec_t

    Wind Energy Production

    As a 3rd year b.tech student you should understand the principle of Conservation of Energy. Any wind-turbine attached to the train will present drag, like a parachute brake used on some aircraft. That drag will oppose the train motion and hence result in an increase in the energy required to...
  8. Alec_t

    What can be happen if I use 10 inch 8-ohms speaker instead of 8 inch 8- ohms?

    Assuming each speaker is in a correctly designed enclosure, you would expect the 10 inch to reproduce lower frequencies more faithfully than the 8 inch. However, build quality of the two speakers is also a major factor.
  9. Alec_t

    Cancel one Light out of another is on?

    Here's one option: The first of switches A and B to close will light a respective LED and prevent the other LED lighting. A momentary push-button switch resets the system.
  10. Alec_t

    Really Need Advice Making Micro Wind Farm

    Not very promising. If one 7ft x 4ft turbine gave 70W then you would need 15 turbines each that size to get 1kW ! You'd need a huge balcony to site them :).
  11. Alec_t

    Heated Gloves

    Something like this would probably do for a PWM controller.
  12. Alec_t

    Timelapse Electronics

    Unless the A4988 board has internal pull-up resistors the unconnected Enable, Sleep and Reset inputs are floating. This is a no-no and can lead to circuit instability, which is possibly why your boards fried. Connect these three inputs to Vdd/Arduino as appropriate (see the Typical Application...
  13. Alec_t

    Heated Gloves

    Your golf trolley probably draws around 10A average. The two pads are rated for 12V so would be ok run from the golf trolley 12V battery. They would would draw 2.5A. So you would reduce battery life by about 20%, i.e. you'd get about 4hrs run time. You may find 15W too much, so a PWM power...
  14. Alec_t

    simple rc timer circuit needed please

    Welcome to EP! How many seconds delay? Does the time need to be adjustable? How accurate does the delay need to be? How much current does the LED draw?
  15. Alec_t

    Really Need Advice Making Micro Wind Farm

    Using the formula I posted earlier, and assuming a 25% efficiency for the turbine, that would produce about 70W in a 20mph wind. Wrong. Neither the frequency nor the voltage of a wind-turbine-driven alternator is constant, so conversion to mains frequency and voltage would be necessary. As for...
  16. Alec_t

    Really Need Advice Making Micro Wind Farm

    Not sure which is height and which is radius/diameter, but something that size will experience a very large force trying to blow it over. Have you thought how you would safely anchor it to the building? You wouldn't want it landing on some passing pedestrian down at ground level :eek:.
  17. Alec_t

    Repairing NCE DCC SB5 model railway control

    How about one of these?
  18. Alec_t

    cd4067be

    The previous two posts tell you two ways :rolleyes:.
  19. Alec_t

    Really Need Advice Making Micro Wind Farm

    Indeed it does. The formula merely gives you the power available in the wind itself. You have to multiply that by the overall collection-efficiency factor of the turbine, taking into account blade inefficiency, friction, mechanical-to-electric conversion, AC/DC conversion etc. I'd be surprised...
  20. Alec_t

    Really Need Advice Making Micro Wind Farm

    This will guide you as to how much power you can generate : Note that the use of several small generators will be less efficient than using one big one.
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