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This morning, while riding my bike, I thought, "Wouldn't it be nice to know when someone is approaching from behind?" I didn't want to use mirrors or funny glasses, so I decided to use an ultrasonic transducer to trigger a buzzer when approached.

This involves a Ping transducer, Arduino, buzzer, switch, 9 volt battery and enclosure.

Thanks to the world of 3D printing, these things don't have to be force fit into a black box anymore.

For the design and print files of the box (created in Autodesk's 123d software--free):
http://www.thingiverse.com/thing:115074

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## Step 1:

I started by piling the major components together to see what sort of space it would take.

## Step 2:

I followed by creating a box--sort of banana shaped instead of rectangular.

## Step 3:

I added the transducer, buzzer and switch.  I didn't get my spacing quite right on the transducer, so I just fit one of the elements into one of the box holes.

## Step 4:

The wiring is fairly minimal, just follow the schematic.

Here is the code for the Arduino:

const int pingPin=7;

long duration;

const int buzzer=3;

void setup()

{pinMode(buzzer,OUTPUT);

}

void loop()

{pinMode (pingPin, OUTPUT);

digitalWrite (pingPin, LOW);

delayMicroseconds (2);

digitalWrite (pingPin, HIGH);

delayMicroseconds (5);

digitalWrite (pingPin, LOW);

pinMode (pingPin, INPUT);

duration = pulseIn (pingPin, HIGH);

if (duration > 12000 and duration < 20000)

{digitalWrite (buzzer, HIGH);

delay(2000);

digitalWrite (buzzer, LOW);

delay(1000);

}

else

{digitalWrite(buzzer,LOW);

}}

## Step 5:

Connect everything together and close the lid with a wood screw.

## Step 6:

Secure to your bike in whatever way is appropriate--I use velcro.

Participated in the
Bikes and Wheels Contest

Participated in the
3D Printing Contest

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## 3 Discussions

When I am ready you will be the 1st to know my friend ! Until then I will keep learning from the Pro's !
Build_it_Bob

Great idea Mike ! I like your custom enclosure too ...you are the man with the 3d printer!
I always enjoy your creative projects ...keep them coming and many thanks for sharing.
Build_it_Bob