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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

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

Tools:
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>Is there a way that you could significantly increase the volume of the buzzer? </p>
<p>Just use a louder buzzer. But this might require a different battery and potentially a transistor to drive it if it needs more current than this chip can output.</p>
<p>I built this today, using parts from Radio Shack, but they didn't have the 4.7M Ohm resistor, and he thought it was probably a misprint anyways.. So he sold me a 4.7 K Ohm resistor. It has not chirped at all, not sure if the resistor is the problem, something I did, or what it could be... I tried the batteries in both directions. Nothing.. Anyone here able to help? , maybe do a video on this?</p>
<p>No. 4.7 Mohm was intentional. It is a less common value though. You could also just use a 1 Mohm. It will just change the timing. If you are still having problems after changing the resistor let me know.</p>
<p>Ok, just picked up some new resistors, got the 1Mohm. They are 1/2 watt, just like the 1Kohm . I was told there is 1/4 watt as well, but I didn't see a specification on this, so I stuck with the 1/2 watt. I'm starting on it now.</p>
<p>The wattage rating makes no difference as long as your circuit doesn't exceed the rated value. In this case, you are well below that. So it doesn't matter. </p>
<p>ok, still not working.. wondering if its my soldering job, or if its perhaps my batteries.. I'm using three Radio Shack 389 which are 1.55V each.??</p>
<p>Hi. I am a frisbee golfer. I live in Oregon where there is a lot of vegetation and we are always losing our frisbees in the bushes/trees/grass... I would like to make a very small beeper to attach to the center of the disc to help us find it. It would have to be VERY small and flat to not affect the frisbee flight. Ideally the size of a quarter or less and have a little button to turn it off and on. It should beep about every 5 seconds or so. Do you think this is possible?</p>
I dont have the spare time to make one of these, can you make one that beeps every three seconds to put on my cat so he cant catch rabbits and squrels
<p>you could try a bell</p>
<p>May I suggest to use a 7555 instead? It will last a lot longer and you might even get away with running the entire thing on 3 volts.</p>
<p>Nix that please. A 7555 is using much less energy, but requires higher voltage. I recreated this project using a ATtiny85 that's 99.9% of the time in sleep mode and lasts 100 days on a single 3V CR2032 coin cell. 8 year old son of a friend of mine drove the teacher bonkers but kept his mouth shut!</p>
<p>I did a bit of re-arranging, and managed to super-miniaturize it as well as provide an alternate power source.</p><p>Thanks for the guide. Now to surreptitiously &quot;break&quot; every computer in the house.</p>
<p>I made this and it is amazing.Though I have one question, how did you calculate the the time gap between each pulse(a beep) and the length of each high signal.I tried checking on the net but couldn't make much of it.</p><p>Thanks</p>
<p>Will you make 10+ plus for me? I don't have the time or materials for this. But I can pay!</p>
<p>Well. This circuit is a 555 timer in astable mode. You can read about this circuit here: <a href="https://en.wikipedia.org/wiki/555_timer_IC#Astable">https://en.wikipedia.org/wiki/555_timer_IC#Astable</a></p><p>The easiest way to work out the timing of this circuit is to use an online calculator such as this: </p><p><a href="http://web.udl.es/usuaris/p7806757/555-calculadora/555%20Calculator.htm">http://web.udl.es/usuaris/p7806757/555-calculadora...</a></p><p>or this:</p><p><a href="http://www.ohmslawcalculator.com/555-astable-calculator">http://www.ohmslawcalculator.com/555-astable-calcu...</a></p><p>or this:</p><p><a href="http://www.csgnetwork.com/ne555timer2calc.html">http://www.csgnetwork.com/ne555timer2calc.html</a></p><p>But if you want to get into the actual math of this circuit it gets a little more complicated. A 555 timer is a 3 input comparator circuit with a built int flip flop circuit. When the input at pin 2 is below 1/3 of the supply voltage, then the output is at pin 3 if HIGH and pin 7 is disconnected. When the input at pin 6 is above 2/3 of the supply voltage, the output at pin 3 is LOW and pin 7 is shorted to ground. So if you start with a discharged capacitor, then the output starts LOW. The capacitor charges through the resistors. Then when it's voltage reaches 2/3 of the supply voltage, it switches the output to LOW and 7 is grounded. The capacitor then discharges through the resistor between pin 6 and 7. When the capacitor voltage drops below 1/3 of the supply voltage then the output switches back and the capacitor begins to charge again. This cycle repeats in an infinite loop. </p>
<p>In the interest of <em>excessive</em> miniaturization, would this work with ceramic capacitors, specifically surface-mount? If not, what alternative type of surface-mount capacitors would be suitable?</p>
<p>As long as the they have the same value, the type of capacitor makes no difference. But you will have a hard time finding a ceramic capacitor this big. Instead, you will want to use larger resistors to compensate for the smaller capacitor values.</p>
<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>use d cells in a wall they last for months, put two sets or more in parallel. The original version of this was called &quot;the tormentor&quot; and the elapse time between beeps was randomized. So you thought you were ready then it didn't then it did then it went faster time, using a nice tough glue inside a desk (I removed drawers), it was never found. Poor nasty Smeagol never could quite figure it out, or find it.</p><p>If you are going to torment a supervisor make sure there are no cameras and use ruber gloves.</p>
Awesome
<p>Is it possible to make this circuit to work not in few minutes but sound commands. For example if my friend coughs then it beeps. If it is possible can you share?</p>
Yes. It is possible to make it react to sound. But people might not hear it if it is beeping at the same time as a loud noise.
<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>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>
Cool

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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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