The Vibrating Belt


Figure 1 :The prototype vibrating belt

This belt came out of the MAS837 class project for a Direction Bump.

Initially, we considered using "push"-type solenoids to push the person wearing the belt and hence the name "Direction Bump".

However, solenoids are pretty heavy, consumes a lot of power and very bulky. So, we looked into using vibrators as the source of the "bump". It turned out that the pager vibrator motors are very small, consumes little power and their vibrations felt easily.

Description

There are eight pager vibrators strapped on a belt to cover eight directions : front, rear, left, right and four intermediate positions. The pager vibrators are little 3-Volt motors with semi-circular weights. The negative poles are all chained together to the negative side of a 3-Volt battery while the positive sides of the motors go through a set of eight transistors, which act like electronic switches. These transistors are driven by the 8-bit data bus of the parallel port of a personal computer. Each transistor is connected to each bit line of the data bus and a program is written to set the states of these 8 pins to either high (5-Volt) or low (0-Volt) state. When the state of a pin is high, the transistor switches on and the vibrator will vibrate.

Figure 2 below shows the circuit diagram of the vibrating belt :


Figure 2 : Circuit Diagram of the Vibrating Belt

Parts

  • The transistors used are 2N3095 NPN general purpose transistors. The way they are connected makes them act as switches rather than as amplifiers.

  • The pager vibrators are from Micromo, part number 06A.

    Future Work

    I am looking into adding more vibrators and multiplexing them so that the 8-bit parallel port data bus need not be used to just control eight vibrators. Serial port to the multiplexer is also a possibility.

    The vibrators need not be tied just onto belts. They can be put anywhere on the surface of our skin, on your head (hidden by grass!!, if any), under hats, under clothings, inside shoes or almost about anywhere.

    Applications

    1.) Direction Bump ( MAS 837 Class Project)

    2.) Silent Early Warning System (SEWS):

    3.) As output device for coded messages