Miniature Beeping Circuit Prank

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.

Step 2: Circuit

The circuit is a basic 555 timer circuit in astable mode. In this configuration the IC sends a brief pulse to the buzzer every few minutes. The values of the resistors and the capacitor determine how often the buzzer will sound and how long each pulse will be. Increasing the value of either the capacitor or the resistor between pins 7 and 8 will increase the amount of time between beeps. Increasing the value of the resistor between pins 6 and 7 will increase the length of each beep. Decreasing these values will have the opposite effect. With the values that I used, it beeps about every 6-7 minutes. (If the capacitor is completely discharged, the first beep may take up to twice as long.)

Step 3: Battery Connector Pins

The only parts that you need to make are the battery connector pins. To make these, cut off two pieces of the paper clip that are about an inch long and fold each of them in half. The bent end is where they will contact with the battery. The cut ends will be soldered to the board.

Step 4: Assembly

Then solder all the components onto the board. If you are using the same PCB, you can just copy my layout. If not, just make sure to follow the schematic on Step 2 and check all the pin connections. When soldering the battery connector pins, try to align them so that they are leaning slightly towards each other. This will help make a tight connection with the batteries.

Step 5: Trim the Circuit Board

After soldering everything together, I trimmed off the unused part off the circuit board to make it easier to hide. I used wire cutters to remove the large chunks and a dremmel to trim up to the edge of the circuit. In hindsight, it would probably be a lot easier to cut the board to the needed dimensions before soldering all the parts onto the board. So if you know where all your parts will be, I recommend trying that.

Step 6: Finished Product

Then just insert the batteries and your annoying beeping prank is ready. Now all you have to do is find a good hiding spot. You can put it inside someone’s computer, tape it to the inside of a drawer, or stick it behind a piece of furniture. Use your imagination. The batteries should last between several hours to several days depending on the size of the battery that you used. But your victim will probably find it before the battery dies depending on how determined/obsessive they are.

Be creative and have fun.

Comments

[lashultz]

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?

[DIY Hacks and How Tos]

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.

[ChaseM45]

I am getting a continuous beep what have I done wrong??

[lashultz]

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?

[DIY Hacks and How Tos]

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.

[Idontunderstandthebatteries]

This is my first time making a circuit board. I am doing well, but I do not understand where the batteries connect. It looks like they connect to the 8 pin, is this correct? Can someone post photos of how they connect to the board, please. Thank you for the help.

[hausofpayne17]

Turned out Great! now I can feed it down the wall cavity to help locate a wire exit. THANKS!

[hausofpayne17]

Thank you so much! I made a beeper that I can feed down a wall cavity to find where it winds up! Using a 12V garage door opener battery. Lots of volume. Substituted a 4.7K resistor and get 0.47s period.

[strawny81]

Can someone tell me how to make this project with a light sensitive diode so when a light is turned on the find it, the beeping stops?

[AricA3]

Will this work with a 12 volt dc power supply??

[gc123]

Is it possible to make a miniature circuit like this the emits a certain hertz frequency/sound?

[salukikev]

1. Is there a simple way to add an LED flash to this circuit?
2. Can I substitute a single button cell (3v) battery?
Thanks!

[lferrelld]

Thanks for the schematic. I Made It... it works great. My 1st prank was at my doctor appointment, it was beeping in my pocket. I was smiling a lot, the assistant said what is it? I asked her did she hear anything, she replied no, I have some hearing loss. The fun was short lived :D

[LimitlessD]

Hi, i have another question. I want something like that.. But than the short beep has to be activevated by pressing push button. the beep/Buzz should stay short not longer then a second, even when you keep button pressed... How would i do that..? and also put in a volume control.. At the end it has to stay small?

I´m new to this hope you could help

[DIY Hacks and How Tos]

I am not really sure how to do that. Holding the button down would usually have a continuous buzzer.

[MarkS-H]

Does this circuit not need a small value capacitor between pin 5 of the 555 timer and Ground?

[DIY Hacks and How Tos]

Not really. This circuit isn't very sensitive so you can leave that capacitor out and your won't even notice.

[kevin.longeuay]

Great post! I actually have a "nicer" 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

[CameronM37]

Hi Kev, Change up the 4.7M res for a value around 50-100k. THat should do it!

[Heather Pooh]

My 9 year old daughter is blind and I'm hoping to figure this little thingy out to put in plastic easter eggs ? I'm also having issues wrapping my head around what combination of materials to use in order to get a 1 or 2 sec interal. If you narrowed it down and figured it out pleeeaaase share the info with me ?