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:

Detect switching ON/OFF of Tube-light with a simple headphone jack

Now in our previous post, we established that the headphone jack can be used to successfully detect electromagnetic disturbances ( Sparks and Lightning ). In this post, we explore the interaction of the tube light with the headphone jack.

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Here is a close up of the peak that you saw in the video:

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Nowadays of course, we have moved on Non-flickering tubelights and it is highly unlikely that we might be able to detect the peculiar peaks that you see on this. But to be sure we are currently working on this and we will keep you guys posted on the results.

Also if we could incorporate this into a IoT network, things will go crazy!!!

 

*   Image Source

Simple Mobile Phone Detector using headphone jack

Mobile phones send wireless signals to the nearby station in order to help you send your message or connect with another phone.

But the best part about this is that these signals can be captured whether or not you have a mobile phone or not.  And the even cooler part about this is that this can be accomplished with nothing more than just a simple headphone jack connected to your laptop/phone.

drawing

There is nothing at all you need to do besides sticking a headphone into your jack and placing a mobile phone nearby.  Then open Audacity and record it at the maximum sampling rate possible on your soundcard. That’s about it !
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Video Demo:

NOTE:

This works remarkably well with older phones (that still use the 2G spectrum), but unfortunately we are still unable to crack into smartphones (that use 3G or 4G spectrum. Argg.. ) using this technique.

But that being said, we are trying our best to crack in. Would highly appreciate any input on this whatsoever. Have a good one!

 

More interesting stuff:

Sound of the dialup modem