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Will this circuit work, and how much power will I need?

Discussion in 'Electronic Basics' started by smpaladin, Oct 18, 2004.

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  1. smpaladin

    smpaladin Guest

    This is a depiction of a circuit that I am planning to make.

    It is a linear motor; Whenever a magnet is passed over the hall
    sensor, it turns on the Power transistor, and therefore turns on the
    Electromagnet coil. In the picture, there are only four sets of the
    hall sensor/transistor/coil. In the real circuit, I am planning on
    having 12 sets of them.

    So will this circuit work properly? And how much power will I need?
    You would think that the circuit would need a lot of power, but then
    you realize that only one set of the hallsensor/transistor/coil will
    be turned on at any one time.

    Any advice is greatly appreciated.
  2. OK, so all you really want to know is the current for one section. No one
    can tell you unless the details of the coil and battery are shown. I.e
    battery voltage and details of the coil. Always include that sort of info
    when asking this type of question. Also what the device is required to do
    usually helps anyone answering.
  3. smpaladin

    smpaladin Guest

    Each coil consists of 15 ft of magnet wire (i'm not sure what type of
    magnet wire, but its slightly thicker than thread) wrapped around a
    1/4 inch thick screw. The coil should be strong enough to attract and
    get a hold onto a similar sized screw from about 1/4 inch away (That
    works with one set of hallsensor/transistor/coil, but the question is
    will it work with 10 sets connected to eachother).

    The transistors are PNP TIP106, and the hall sensors are PNP 21E.
  4. rayjking

    rayjking Guest

    You also need to add a resistor in series with the transistor base to
    protect the halls and connect a clamp circuit across the motor coils to keep
    the transistors from failing.
    The motor rpm is limited by the rate of current build up and should have the
    same rate of current decay or faster. What ever the battery voltage is the
    clamp should be higher. one way is to add a clamp diode across each motor
    coil with a zener diode in series with the clamp diode that is at least 30%
    higher than the battery voltage. The transistor voltage will see the battery
    voltage + 30% + the battery voltage.

    Fets are best.

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