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Vibrotactile Device

Hi,

I am trying to build a portable device that takes vocal vibrations (from a piezo mic attached to the throat) and outputs them as tactile vibrations elsewhere (say at the sternum). I've found and built simple circuits for preamps that run off 9V like this one (https://www.instructables.com/id/Make-a-Simple-Audio-Amplifier/?ALLSTEPS) but I'm struggling to work out how I can connect and power a vibrating device (e.g. another piezo mic) for the output. 

I guess I will need to include a low pass filter too to prevent the device creating audible output (I just want low frequency tactile vibration).

I've seen a similar project here https://www.instructables.com/id/Representing-audio-through-vibration-with-Arduino/?ALLSTEPS but it's using an arduino and I feel like that's unnecessary for my purposes. 

Any ideas really appreciated,
Oli

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By accident I came across thereal thing:

http://www.ebay.com.au/itm/Bone-Conductor-Transduc...

Maybe it is worth checking for your project?

ocheadle (author)  Downunder35m2 years ago

Thank you - That might work great!

ocheadle (author) 2 years ago

Thank you Downunder35m and caitlinsdad! I might end up trying one of those loudspeakers but I'd like to keep costs down and a pager motor sounds simpler than a piezo to use, so I'll start there.

Cheers,

Oli

Do you just want some sort of vibration or a vibration that resembles the input signal?

Just asking as a vibration motor does just that - it vibrates.
Frequency depends on the speed of the motor (input voltage) and it won't change with the audio signal much.

ocheadle (author)  Downunder35m2 years ago

Good point. No I want to vibration to reflect the signal in some way and not just vibrate at one frequency when you speak. So, you're right a transducer like you mentioned would be needed.

I think I'm going to try and pick up a used pair of these headphones:I'll try to remove the built in vibration motor and use that for my output. Will keep looking for a way I could build this myself but it might be a bit beyond my electronics skills right now.

Cheers

There is no video in it at least not for me :(
If you want to try to build something very simply (no guarantee for good sound quality):
Take a cylindrical magnet and glue a compression spring to one end.

Place it into a suitable coil (hand wound to match diameter of magnet and get to 4 or 8Ohm resistance).

The magnet should stick a little bit out of the coil and outwards the centre of the coil in unused condition.

When in use the coil and magnet should sit flat on the surface and the magnet centred in the coil.

If now an audio signal goes through the coil the magnet will be pushed/pulled accordingly.

ocheadle (author)  Downunder35m2 years ago

Sorry, they are called Skullcandy Skullcrushers. There's a video of them being taken apart here. Thanks for the tactile stimulator idea. I will let you know if I try it!

caitlinsdad2 years ago

Someone with more electronics knowledge will have to give you the details but I think you have the part of getting an output from the piezo pickup. That signal is amped up to a certain voltage range. It can then drive a relay or a transistor which controls the power going to a vibration motor. Piezos are like one revolution motors, you have to keep appyling a pulsing on-off on-off switching PWM(pulse width modulation) to make them vibrate which has to be generated by more circuitry. So for the output in your microprocessorless design, one of those cellphone pager vibration motors would be better. Good luck.

There are "loudspeakers" out there that use suction cups or glue to be fixed on a flat surface.

The audio signal is transfered into vibrations of a transmitter - basically a speaker that has a vibrating pin instead of the membrane.

As a gadget with battery supply to be mounted on a window of table they cost less than 50 bucks, cheaper if you shop around for a bargain.

Professional speakers of this kind are glued to glass surfaces that act as a speaker.

There has also been an instructable with those speakers, to be found here:

https://www.instructables.com/id/Glass-Speakers/