This little device is a fun tool for pranking your friends and coworkers. Every few minutes it emits a brief, high-pitched beep. The beeping gets annoying after awhile, but what is really frustrating is not being able to find it. If you choose a good hiding spot, it can take hours to figure out where it is.

Step 1: Materials

Jumper Wires
3 Button cell Batteries (I used LR932 cells but other sizes will work)
Printed Circuit Board (RadioShack #276-159)
3-16V Piezo Buzzer (RadioShack #273-074)
100μF 10V Capacitor
555 Timer IC (RadioShack #276-1723)
1kΩ Resistor
4.7MΩ Resistor
Large Paperclip

Soldering Iron
Dremel (optional)

Part Substitutions:
The values of the capacitor and resistors are not critical. You can easily replace them with capacitors and resistors of similar values. The only effect will be that it changes the time between beeps. See Step 2 for a better explanation.

The PCB can also be replaced with any other PCB with enough holes to fit all the components.
<p>Finally got around to doing this prank. Thanks for the tutorial.</p><p>I put this beeper in the walls of the house, and they couldn't find it for a 5 days. I made sure to use alkaline AA batteries to make it last longer.</p><p>I used a 330 mF cap, 2M Ohm R1, and a 560 Ohm R2. It beeps for 0.1 ms every 8 minutes (approx). I found that this combination was the most noticeable, while still having a long enough interval so that it's hard to find.</p><p>Only disadvantage is the size, but it's still small enough to fit behind a light switch in the wall.</p><p>Thanks again!</p>
<p>Great tut</p><p>How long do the batteries last?</p><p>What kind of battery and how many should I use so that this buzzer beeps for a week (7 min intervals).</p>
It all depends on the batteries that you use and the exact parts that you build it with. The battery should have a mAh rating. Divide the mAh rating of the battery by the current rating of the Timer IC and that is how many hours it will run for. But in most cases, they will find it long before it runs out of batteries.
<p>Thanks, I added the buzzer mAh to the denominator too. (That's correct, right?)<br><br>Also, why did you choose 4.5v, why not use 3v?</p>
<p>The timer IC will be on all the time. The buzzer is almost never on. So it doesn't factor in as much. 4.5V is the lowest voltage the the timer IC will work at. It can't run on 3V</p>
<p>Really good prank and also really funny. Though i didn't get the cause of the time gaps between each beeb</p>
<p>Sorry,what i meant by the question was that how does the capacitor determine the time gap between each beep.</p><p>Thanks for the quick reply!</p>
If it is constantly beeping, it would be really easy to find. But if it only beeps every few minutes, it is much harder to track down making it even more annoying.
<p>I want to make a device which beep when I press a button, can someone help me how to build up such a device.</p>
Just get a 3 volt piezo buzzer and connect it to a battery with a switch.
<p>A great way to hide this would be to stuff this into a wall wart with a voltage regulator and a resistor.</p>
<p>I am a novice, but this seemed like a do-able project for me. Your instructions were very easy to follow and detailed, so I was very surprised when I couldn't get this to work. For some reason, I keep getting a static/chirping type sound from it, but no beeps. Any idea what could cause this?</p>
Make sure that you are using a piezo buzzer and not a speaker. The beep pulse may also be to short for the buzzer to really sound. Try adjusting the values of the smallest resistor.
<p>It is a piezo buzzer. In fact I used all of the same parts that you described except the largest resistor (10M was the closest I could find). I started with the 1K for the smallest and changed it over to a 22K and still nothing :-/ I've looked over your pictures several times and everything looks right. Just wondering if perhaps there is a common mistake that I'm making or what?</p>
<p>Replace the buzzer with an LED and see if it blinks when it is supposed you. Then check the buzzer with a battery to make sure that that is working. </p>
<p>Worked out great. I powered it with a usb cable. Going to plug it into the back of someones computer or tv ;) Used a 1M resistor to decrease time between beeps and a 2.2k to increase length of beep.</p>
<p>Awesome. Thanks for sharing.</p>
<p>Nice use of the standard astable mode. On a side note I am making around 30 of them for April 1st, parts are ordered now to wait the 2 weeks from china shipping. Only I am using an hour interval for longer run time and to make it harder to find them.</p>
Sounds like fun. Let me know how it turns out.
<p>I dont know how to read a circuit diagram well. Where do the - in and + in go?</p>
<p>Here is a tutorial on how to read circuit diagrams.</p><p><a href="http://www.instructables.com/id/HOW-TO-READ-CIRCUIT-DIAGRAMS/" rel="nofollow">http://www.instructables.com/id/HOW-TO-READ-CIRCUI...</a></p><p>The + in is the 4.5V supply voltage from the battery.It is connected to the speaker, pin 4, pin 8, and the 4.7Mohm resistor.</p><p>The - in is the common ground and is connected to pin 1 and the capacitor.</p>
Great post! I actually have a &quot;nicer&quot; use that I'm to build for... My cousin works with blind kids and they've been looking for a beeping hockey puck so this could be perfect for it! Any recommendation on a capacitor for a one second beep interval? Also, any idea how to ruggedize
The easiest thing to do is use a 555 timer calculator like this one.<br>http://web.udl.es/usuaris/p7806757/555-calculadora/555%20Calculator.htm<br>
Perfect! Thank you
<p>Outstanding instructions! I used a 555 CMOS and dissected an A23 battery to get the (3) button-cells. If you follow the pics...everything goes together perfectly! Didn't have to breadboard, the schematic made it very clear. Thank you <a href="http://www.instructables.com/member/DIY+Hacks+and+How+Tos/" rel="nofollow">http://www.instructables.com/member/DIY+Hacks+and+How+Tos/</a></p>
Awesome. Thanks for Sharing.
<p>I made it! I powered it with a 9v battery and made it on a breadboard soon I will put it in a pcb board or stripboard. Thanks!</p>
<p>Can this be powered by a 9v battery?</p>
Yes, all the parts that I used can handle 9 volts.
<p>Up to how much voltage can this circuit handle?</p>
I built one of these, but added a photocell so that it would only chirp in the dark. Much harder to find!!
I'm curious as well. Where did you place the photocell so that it would only chirp in the dark?
Now THAT is mean!<br>Especially if you put it somewhere around the bedroom where the victim goes crazy to its beep and can't sleep from it... imagine it shutting up every time you open the lights to search for the annoyance!<br><br>Did you just add it serial after the battery?
I want to make one of these but with a vibration motor instead, if I were to replace the piezo buzzer with a transistor switch connected to the electric motor, would that work? I'm just not sure about the negative connection from the buzzer going back into 3. Is that a necessity for that to happen?
The 555 timer IC can output 200mA of current. So if you can find a motor that runs on less than that, you could just hook it up directly in place of the buzzer and you wouldn't even need a transistor.
you reckon a vibrator motor from an xbox controller would be less than 200mA? because I have no clue. if not, I've got plenty of old phones I can steal one from, that'd work, and it'd be a very small amperage.
I don't know about that motor specifically .If you can't find the specs and you are brave, you could just try it out and see if it breaks. Alternatively you could take a motor that you already know the power rating for and turn it into a vibrator motor. http://www.instructables.com/id/How-to-make-a-vibrating-motor./<br>
I pulled one out of an iPhone, should do the trick, really, it's tiny, and it wouldn't be in a phone if it was high current. Thanks for the help.
Thank you DIYHacksAndHowTos for this wonderful instructible.I modified your circuit to successfully make an indicator for my bike.
Mine works fine. Short beep every 6 minutes or so. My problem is the battery life. The 3 button batteries only lasted a few hours. Switched to a 9v and only lasted about 10 hrs.
You are absolutely right. Even I have a bill with 1k resistors on it, I have a 100k resistors instead. Problem solved. Thank you. This works with 3V CR2032 battery, but times are longer.
I make the same circuit as described on protoboard and have a problem with beep duration. Duration between two beeps is about 12 minutes first time, then it takes about 6 mins for next beeps. That is ok. But beep duration is too long, about 6 seconds. As I sad, I use the same components for circuit. What is the problem?
The first beep should take twice as long if it has been off for a while and the capacitor discharged. Also, double check your resistor values. That sounds like the timing thatyou would get if you are using a 100k instead of a 1k. Here is a helpful calculator that might help. <br>http://www.csgnetwork.com/ne555timer2calc.html
If you go to the website home page (www.555-timer-circuits.com) there is 55 circuits to do with a 555 timer.
If You put a photocell in the circuit and then put it in some ones bedroom, while at the same time hide a camera to film their face and posting it on YouTube at April's fools day would be cool!
Thanks !
Wich value would r1 have to be to beep every 5 minutes?
Here is a web page with a calculator for 555 timer circuits

About This Instructable


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Bio: My name is Jason Poel Smith I am a Community Manager here at Instructables. In my free time, I am an Inventor, Maker, Hacker, Tinker ... More »
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