Vibration motor meets the Headphone jack

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Although vibration motors are common in Mobile phones, procuring button sized vibration motors were the ultimate challenge. (There were a couple of good ones on ebay, but couldn’t find one at this point of time)

But once that was resolved, one of the leads of the vibration motor was connected to the headphone jack and the ground of the headphone jack to the other lead.

Now square wave signals are played through the headphone jack using Audacity. Although one can feel the motors vibrating, using an operational amplifier such as LM324 helps to intensify the vibrations. ( Power source to LM324 – Battery/Arduino )

drawing

 

 

Note:

One of the weirdest but yet satisfying experience with the vibration motor is when you connect the vibration motor through the audio jack without any amplifier. You can hear the music being played through the vibration motor. The motors seems to be dancing to the music being played. We tried so hard to capture the phenomenon but the sound was too feeble to be picked up. That shouldn’t stop you from giving it a shot.

The headphone jack meets an actual spark gap!

So, we had the opportunity to test out the headphone jack with an actual spark gap and it was absolutely wonderful. Check it out:

With the data we can actualy find out the frequency of the spark occurrence. In our case it turned out to be ~ 34 – 36 Hz. And since this is in the Audible range we can actually hear this (somehow we missed this when making the video)

Screenshot from 2017-06-10 20:01:07

Audio file : GoogleDrive

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Part – I – Lightning detector with a simple headphone jack

Part – II – Detecting switching ON/OFF of Tube Light using headphone jack

Part – III – Cigarette lighter spark detection using headphone jack

 

It is ridiculously easy to generate any audio signal using Python

Updated: May 15,2019

Now it comes as a surprise to many people when I tell them that generating an audio waveform is extremely simple.

One needs to have basic understanding on how audio signals work and basic python programming to generate any audio wave form. This post will show you exactly how.

Python packages needed: Numpy, Scipy

Screenshot_2019-05-15_11-06-02

How to play the audio the generated audio file on computer ?

1. Command line using SoX

play -t raw -r 44.1k -e signed -b 8 -c 1 test.wav

where -r = sampling rate -b = sampling precision (bits) -c = number of channels

2. Use Audacity (check video)

 

Link to code : GitHub

You can find a list of other waveforms that can be generated using SciPy here

Known Issues:

[1] This does add any headers to the audio file and therefore you cannot play it on any media player as is . Check this reddit post if you really want to have one.

[2] Adding headers to the above code seems to be making it slower. And this is a problem if you want to make larger audio files.

[3] The code generates only 8-bit audio signal. Feel free to play around with the code to change it to other formats.

[4] A lot of technical details were conveniently not included in code in order to appeal to the theme of this post. And therefore this code is not “efficient”.

DIY: Obstacle detector with Audible feedback (IR sensor + Headphone jack + 555 timer)

We were inspired by the buzzer that you find in mobile and laptop showrooms – the ones that produce this annoying high frequency tone if you fiddle a ‘little too much’ with the displayed product.

schematic

We use a 555 timer in its Astable mode to produce the frequency tone and couple it with a digital IR sensor module. We do this by connecting the output pin and the ground parallel to R2 in the figure.

single-ir-sensor

And as a result when there are no objects in the vicinity, the system produces a high frequency tone, but when an object is introduced the sound dies out.  This is attributed to the change in resistance value.

Here is another variation of the same: