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I am building a vibrating device for that I am thinking to use a solenoid for vibration. The solenoid will be used such that device will be mounted in the floor and when a stick is put over solenoid, it will start vibration. That vibration needs to be felt by the person holding the stick so so that say she can count those and recognize patterns of vibration.

I come to know through responses to my another question that solenoid may be not a good choice as it is not a vibrating device. Rather an offset weight motor may serve the purpose better. I did not know about it. I search for offset weight motor but did not find any link to that.

My question is which equipment should I choose for generating vibrations for my device? Can someone put a link of offset weight motor so that I may read about it. I also learned that offset weight motor acts like a mobile phone vibrator. That is good for my project as I may extend the output to be read by a mobile later so it will help.

enterprize
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  • possible duplicate of [Do I need a Pull type solenoid or Push type?](http://electronics.stackexchange.com/questions/75484/do-i-need-a-pull-type-solenoid-or-push-type) – Leon Heller Jul 10 '13 at 13:16

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A solenoid is sub-optimal for generating ongoing vibration. If the intent were to generate a single shock intermittently, then sure, a solenoid would be a good choice.

For mechanical vibrations (presumably for sensing by human touch), two options are popular:

  1. Offset Weight motors, aka pager motors, vibration motors:

    • These are available down to very small sizes, and very low current and voltage ratings, such as 1.5 Volts, 10 mA in 3mm x 3mm x 5 mm, surface mounted.
    • Operating them from your circuit is simple, even trivial.
    • Downside: Very precise start and stop timing is not feasible, and vibration frequency is not simple to modify.
    • Mobile phones (and of course pagers in ancient times) typically use such motors for vibrating ring notification:
      Pager Motor
      (Source: eBay.com, Vibrating Micro Motor - 1 to 4.5 V - 13 mm x 7 mm)

  2. Piezoelectric benders aka coin-type speakers:

    • These exist in very small heights, down to under 0.5 mm, but diameter is usually 5 to 10 mm for effective output.
    • Actuated by a haptic driver or haptic controller IC, or even an oscillator at desired vibration frequency, these are a little more complex to drive. Some such haptic piezo actuators require tens or even hundreds of volts, although at minuscule current. The haptic drivers typically generate the required voltages internally.
    • Both vibration frequency and start/stop time can be controlled with great precision.
    • Mobile phone haptic feedback, i.e. the mild buzzing sensation some mobiles offer to indicate the press of a key on a touch screen, for instance, typically use this mechanism.
    • For an example of a piezo haptic driver with an integrated voltage boost converter, see the Texas Instruments DRV8662.
      Piezo Speaker
      (Source: eBay.com, 12mm Piezo Disc)
Anindo Ghosh
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  • thank you very much, this makes things more clear to me. I am not building solution for sensing by touch rather by a walking stick. Solenoid appears to be choice as these offset weight motor appear generating very weak vibration for it to be sensed through a walking stick & vibration patterns to be recognized. – enterprize Jul 10 '13 at 13:45
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    Offset motors are available in hugely powerful multiwatt models as well: Also, an offset motor is nothing but a conventional rotary motor (DC, BLDC, whatever) with an unbalanced weight attached to the shaft. You could make one yourself from your choice of motor. A solenoid will not last long under repeated vibration. – Anindo Ghosh Jul 10 '13 at 13:49
  • yes,life time of a solenoid is a concern as it gets warm very quickly.Offset motor actually will suit more for my work as I mentioned in OP,I will expand this reading by walking stick to reading by mobile too.& this will help me.Can you please suggest some offset motor that is powerful enough to generate vibrations that are sensed by a walking stick i.e. a white cane or some guideline for that.If I get an off the shelf solution it will help. – enterprize Jul 10 '13 at 14:37
  • [PrecisionMicrodrives](https://catalog.precisionmicrodrives.com/order-parts/product/345-400-45mm-vibration-motor-28mm-type) or [eBay](http://www.ebay.com/itm/Mabuchi-555-Massager-Motor-12V-DC-4000-RPM-Heavy-Vibrator-Brass-Weight-/271208234074?pt=LH_DefaultDomain_0&hash=item3f25453c5a) or [dhGate](http://www.dhgate.com/product/m20-vibration-motor-6v-9v-powerful-miniature/143534908.html) – Anindo Ghosh Jul 10 '13 at 15:04
  • I built a vibration platform from a surplus $5 AC motor (no power rating shown, but it fits in the palm of my hand) and a 3 ounce weight. Even when mounted by suspension from rubber straps and sitting in my basement, the vibration can be felt at the other end of the house. For a very small amount of power, you can achieve extremely strong vibration. Go with the motor! – lyndon Jul 10 '13 at 16:37
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Info: http://www.precisionmicrodrives.com/application-notes-technical-guides/application-bulletins/ab-004-understanding-erm-characteristics-for-vibration-applications

Item: https://www.sparkfun.com/products/8449

Hope this helps.

Dave
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I'd use a cam on a regular motor to move the stick. This turns into a mechanical problem

Scott Seidman
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