Sonic Mind Molester (Arduino Chirp Prank)

I'm a bit of a prankster with friends and family. Nothing like that crap that you see on social media, but I do like to prank along the way. I recently recalled seeing something in an old ShomerTec catalog that would randomly emit a chirping sound as long as it had a battery connected to it. Figuring that I'd pick one up, I hopped online and started looking around but couldn't find it anywhere. ThinkGeek had the Annoy-a-Tron as well, but they're "currently unavailable" on Amazon. I then thought about making one out of a 555 timer and some perf board but then it donned on me; I have a handful of small Arduino Pro Micro clones laying around from a previous project...I'll just use one of those.

I figured that I'd put it up on Instructables if anyone else wants to play around with some friends, (although I'm sure that there are 900 different iterations of it out there online).

This should go without saying, but:

Use this information and sketch (code) at your own risk. I will not be responsible for any shenanigans that you wish to partake in; this includes any and/or all improper or illegal conduct. If HR fires you for harassing your co-workers, that's 100% on you. Now that had been said, let's move on.

Parts Needed:

• Arduino Pro Micro (or equivalent) - I got a 3 pack of Clones from Amazon for $22
• 9v Battery (other battery options from 5v-12v are available, but 9v is the quickest/easiest)
• 9v Battery Clip - Also purchased from Amazon
• 5v Piezo Buzzer - From Amazon
• Small Strip of Double Sided Tape (or some method of sticking the Pro Micro to the battery)

Tools Needed:

• Soldering Iron
• Solder
• Micro USB Cable
• Arduino IDE Software - Available here
• And Obviously, a computer to run the Arduino IDE software

Get everything laid out, get your soldering iron plugged in and warmed up, and get ready to go...

In the case of my piezo buzzer and my desire to just solder it directly to the board, I ended up placing the ground pin into the first ground pad after "RX1" and the positive pin into pad "3".

*It doesn't really bother me that it is sitting at an angle, but if you wanted to, you could solder in wire to jump from the buzzer to the board and allow the buzzer to 'free-hang'.

After soldering the buzzer in place, I snipped the leads to get them as close to the solder 'cone' as possible.

*Ignore the heatsink that is on the Arduino; I put it on there for something else entirely and just didn't feel like trying to take it off.

I got a handful of these 9v power connector leads off of Amazon for a few bucks; putting one of them into play is really easy and straightforward.

The length is a little long, so stretch it out and cut the excess off at around 1-1/4" (1.25" or 32mm). This will give you a nice little pigtail that gets soldered to the board.

Pre-tin the leads and solder the red power lead into the "RAW" pad and the black negative lead into the "GND" pad right next to it.

~From Sparkfun:

Alternatively, if your Pro Micro is living out in the wild, out of reach of USB cables, it can be powered through either the 'RAW' or 'VCC' pins. A supply going into the 'RAW' pin will be regulated down to the correct operating voltage (5V or 3.3V). To be safe, it shouldn't be any higher than 12V, and it should be at least 1V more than the Pro Micro's operating voltage (e.g. >6V for a 5V Pro Micro).

If you power the Pro Micro through the 'VCC' pin, keep in mind that this signal is unregulated. Only use this if you have a clean, regulated 3.3V or 5V supply to connect to it.

Additionally, if you plan on placing this gizmo in an area that is close to a USB cable (i.e. near a computer, router, or newer tv), you can always ditch this step and just use a USB cable. Likewise, if you want to place it near a plug, you can also use a USB wall wart to supply it with power indefinitely.

I had some clear VHB from another project laying around, so I decided to get that to work instead of electrical tape, glue, or making an enclosure. I just chopped off a little piece that was roughly the size of the Pro Micro and stuck it to the bottom of the board; then stuck it to the side of a 9v battery.

This is where some downside comes into play. I don't know how much power this consumes (I have to wait on a multi-meter fuse to be delivered before I can test it) and a 9v battery is only about 500mAh (capacity), so I'm not sure how long this particular setup would last before the battery is flat.

Technically, you could always get a cheap power brick and run a small USB from it to power the gizmo. I guess that it all depends on where you want to try and hide it and how long you want it to 'run'.

Below is the sketch that I put together. I am certainly not an Arduino expert or anything like that, so there may be a better way to go about doing it. The sketch is everything between the dashed lines and I tried including notes to keep track of which parts do what. *Or if you wish, you can download the included .ino file at the bottom

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//Arduino Pro Micro "Sonic Mind Molester" (Random Chirp) Prank Sketch

//I'm not responsible for your shenanigans...If you use this in an improper or illegal way, that is on you!

//This uses a basic 5v Piezo Buzzer that you can find on Amazon or eBay for cheap

//by: BanishedSpectre

long randDuration; //establishes randDuration (random duration)

long randWait; //establishes randWait (random wait)

int SPK = 3; //pin used for positive side of piezo buzzer

void setup ()

{ pinMode(SPK, OUTPUT); //setup pin mode for output

}

void loop ()

{

//randDuration is Playing tone between 0.05 and 0.1 seconds - Keep this number relatively short.

randDuration = random(50, 100);

//triggers speaker voltage on

digitalWrite(SPK, HIGH);

//continues to play tone to the time of randDuration

delay(randDuration);

//turns off speaker voltage

digitalWrite(SPK, LOW);

//randWait is waiting between X and Y seconds (number in milliseconds)

randWait = random(1000, 3000);

//1000, 3000 is just for testing, change to a more realistic number before planting

//Time Equation Reference

//10 seconds = 10000

//30 seconds = 30000

//5 minutes = 300000

//15 minutes = 900000

//1 hour = 3600000

// To help prevent the device from being found, I would suggest a X time of 15 minutes (900000)

// and a Y time of 1 hour (3600000). Either way, keep in mind that you'll also eventually have to

// change out or re-charge the battery at some point.

//continues to be silent to the time of randWait

delay(randWait);

}

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Once you have the code copied and pasted into a new Arduino sketch, save it and upload it to your Pro Micro. After the Arduino restarts (and if you temporarily left it with the "1000, 3000" time), it should trigger every 1-3 seconds to allow you to check your work (i.e. make sure there are no typos, that the soldering is good, that you didn't solder the wrong pin(s), etc).

If everything is good and it's chirping as it should, you can then change the wait time ("randWait") to something more realistic and upload it to the board.

If you watch the video, you'll notice that it's not super loud and I really didn't want it to be. I wanted it to be somewhat "level" or 'not over the top' so that it is harder to pinpoint its location.

Keep in mind, it will always do the first chirp when you supply it with power, then after that, it's the waiting game until the next one. Don't be surprised if someone automatically assumes that the smoke detector batteries need to be changed out.