Author Options:

I want to make an audio-to-vibration bracelet for my deaf partner. I need help! Answered

I have a new baby and my deaf wife can't hear the baby at night.

I want to make a bracelet that vibrates with sound over a minimum volume.

I thought about using a Raspberry Pi Zero, but it seems like overkill (and large!). Is there a simple circuit I can make that could house a microphone, vibrator, battery and some chip to make it work? I'm pretty green to circuitry in general so need some handholding if possible.



The forums are retiring in 2021 and are now closed for new topics and comments.
Josehf Murchison
Josehf Murchison

1 year ago

A simple circuit like this with the vibrator from a cell phone should help.
It only needs a BC547 transistor, a 15 k ohm resistor, a mike, and a 3.7 volt battery.

Audio Drive a.gifAudio Drive b.bmp
Jack A Lopez
Jack A Lopez

1 year ago

I have a quote for you, from the Wikipedia article for, "Baby monitor," in the section titled, "Other features." I have used bold type to emphasize some of the parts I think are pithy.


"Portable battery-operated receivers can be carried by the parent around the house. The transmitter stays near the infant crib and is usually plugged into a socket. Some baby monitor packages include two receivers."

"Baby monitors may have a visible signal as well as repeating the sound. This is often in the form of a set of lights to indicate the noise level, allowing the device to be used when it is inappropriate or impractical for the receiver to play the sound. Other monitors have a vibrating alert on the receiver making it particularly useful for people with hearing difficulties."

The reason I am pointing you towards this Wikipedia article is because, as far as I know, these baby-monitor gizmos represent the state of the art with respect the surveillance of babies by listening to the sounds they make.

An essential feature of these kind of baby monitors, is the microphone is placed in the crib with the baby.

The reason for doing it that way, rather than placing the microphone somewhere else in the house, e.g. on a bracelet worn by one of the parents, is because that location, in the crib with the baby, is the best place to pick up sound made by the baby, and not pick up sound from other sources.

I admit that it would be very convenient if the whole system could fit into a bracelet-sized gizmo, to be worn by one of the parents, but I think that is going to be a lot more challenging than doing it the old fashioned way, i.e. microphone and radio transmitter in the crib, and a matched radio receiver, worn or carried by the parent.


1 year ago

Interesting problem...
I could think of using two Arduino Uno or even Nano for this.
On the baby side with a little sound module to detect noise - like all these DB measuring applications.
There should be something to read about this in the Arduino Playground.
An added BT or WiFi module (depending on the required range) to commicate with the recieving Arduino.
For the recieving side you only need to add a transistor circuit to drive a cell phone vibration motor for the selected duration or for as long as the sender detects a noise level above ambient.

To make the functions a bit clearer:
A simple microphone module or circuit is used to detect the noise level in the room.
The Arduino is programmed like a decibel meter where you can set a fixed DB level to activate the BT or WiFi module.
Of course this can be simplyfied as well by just using a transistor to activate any RF transmitter, like from a cheap Ebay remote with a 5V or below supply voltage on either end - be creative and use what you can ;)
Once the ambient noise level goes about the set threshold value the output to transmit the signal is activated - be it for the BT, WiFi or RF.
It can be either ON for as long as the noise level is above the limit or set to a fixed duration.
For the receiving end:
Once a signal to activate is recognised the output for the vibration motor is set to high and the added transistor protects the output while driving the motor.

There might be an alternative though, considering your partner is blind and most likely quite sensitive to vibrations of any kind:
Using a simple auido transmitter system.
I did a quick test with a leftover headphone speaker to confirm the theory should work!
These cheap over-the-ear-headphones often use suprisingly powerful speakers in them.
And in many cases they are quite flat in their design.
If these flat speakers are placed directly on a sensitive part of your skin you feel the sound.
That alone however really is of no good use.
I cut a round disk of a thin copper sheet (anything non magnetic will do) with the size of the coil in the membrane and glued it in the center of the speaker membrane.
This added weight was enough to "amplify" the vibrations on the skin.
I am not sensitive enough to make a proper judgement of what I actually felt but for example things like a bass rythm definately felt different than just a singer or a talking voice.
I am quite confident that with a bit of experimenting on the speaker side and the weights your partner should be able to distinguish between for example the crying baby or the baby making noise when tossing some things out of the cod.
Worth a shot just trying with a little salvaged speaker and using some suitable sounds from your mobile phone or such ;)