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Rotary motor specs & step-changing voltage

Discussion in 'Sensors and Actuators' started by starsky, Jul 15, 2013.

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  1. starsky

    starsky

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    Aug 14, 2012
    Hello all,

    I wonder if anyone could help me with the following:

    1. I am trying to locate the data sheet for a Sanko Electric (Taiwan) miniature rotary motor (part #1E120). It appears to be an old part, which no-one appears to stock any longer. It's a bit of a long shot but I was wondering if anyone had the data sheet or if anyone knew how I might be able to obtain it?

    2. I need to vary the drive signal voltage similar to what is shown in the attached graphic. Is this relatively straightforward to do and are there any off-the-shelf chips that can be bought that do just this? The step-changes need to be random over time but this randomness doesn't have to be infinite (i.e., the random signal could run for, say, 10 minutes and then started again).

    Thanks in advance for your help.
     

    Attached Files:

  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,268
    Nov 28, 2011
    I can't help with your first question, except to suggest that you look for a similar product from a different manufacturer.

    As for the second one... The obvious answer is a microcontroller with a DAC (digital-to-analogue converter). Digital-to-analogue conversion can also be done using a network of resistors called an R-2R ladder, or using a technique called PWM (pulse width modulation).

    Microchip (http://www.microchip.com) make a series called PICs, some of which have DACs (and all have PWM capability), and Atmel (http://www.atmel.com) make a series called AVRs. There are many other small microcontroller architectures, but these are probably the commonest and many people here are familiar with them. Apparently random sequences can be generated using a pseudo-random number generator based on a linear feedback shift register, which can be implemented in firmware pretty easily.

    Another option would be to use a noise generator circuit and a timed sample-and-hold circuit, but this would require a lot more circuitry.

    You will also need some kind of variable regulator to drive the motor with the chosen voltage. Or you may be able to drive the motor directly with a pulse width modulated signal; in this case, you only need a switch between the power source and the motor; a small MOSFET is well suited to that application and no heatsink will be needed.

    I suggest you google the terms I've mentioned, and have a think about which way you want to go.
     
  3. BobK

    BobK

    7,682
    1,685
    Jan 5, 2010
    Just out of curiosity, why do want to do this? I have never heard of applying a randomly varying voltage to a motor.

    Bob
     
  4. starsky

    starsky

    5
    0
    Aug 14, 2012
    KrisBlueNZ - thanks very much for you input. I shall follow-up your suggestions and see whether they are suitable for my application.

    BobK - it's for an invention I am working on. I am trying to generate some random vibrations using a miniature eccentric rotating mass motor. If I just ran the motor at a particular speed using a single voltage it wouldn't be random hence why I need to constantly vary the voltage.
     
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