Instructables

Miniature Beeping Circuit Prank

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Picture of 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.
 
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Step 1: Materials

Picture of 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

Picture of 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

Picture of 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.
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mark999 made it!2 months ago

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!

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DIY Hacks and How Tos (author)  mark9992 months ago
Cool
mark9992 months ago

Can this be powered by a 9v battery?

DIY Hacks and How Tos (author)  mark9992 months ago
Yes, all the parts that I used can handle 9 volts.
mark9992 months ago

Up to how much voltage can this circuit handle?

krich2 years ago
I built one of these, but added a photocell so that it would only chirp in the dark. Much harder to find!!
EEWolverine krich6 months ago
I'm curious as well. Where did you place the photocell so that it would only chirp in the dark?
Now THAT is mean!
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!

Did you just add it serial after the battery?
kschmidt27 months ago
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?
DIY Hacks and How Tos (author)  kschmidt26 months ago
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.
DIY Hacks and How Tos (author)  kschmidt26 months ago
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./
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.
Adarsh_tronix7 months ago
Thank you DIYHacksAndHowTos for this wonderful instructible.I modified your circuit to successfully make an indicator for my bike.
Eirik10101 year ago
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.
kosmar1 year ago
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.
kosmar1 year ago
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?
DIY Hacks and How Tos (author)  kosmar1 year ago
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.
http://www.csgnetwork.com/ne555timer2calc.html
Ploopy1 year ago
If you go to the website home page (www.555-timer-circuits.com) there is 55 circuits to do with a 555 timer.
Ploopy1 year ago
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!
Ploopy1 year ago
Thanks !
Ploopy1 year ago
Wich value would r1 have to be to beep every 5 minutes?
DIY Hacks and How Tos (author)  Ploopy1 year ago
Here is a web page with a calculator for 555 timer circuits
Ploopy1 year ago
Does the chip get hot?
I read in http://www.555-timer-circuits.com/common-mistakes.html
that higher than 5 minutes gets the chip hot
DIY Hacks and How Tos (author)  Ploopy1 year ago
No the chip does not get hot with this circuit.
eliobou1 year ago
What have I to change if I want to increase the delay between two "beep" ?
DIY Hacks and How Tos (author)  eliobou1 year ago
"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."
Ploopy1 year ago
Cool prank
gamewiz7242 years ago
just tried building this but it beeps for a while then stops then beeps again for a long time, any ideal what i did wrong? Also i noticed that on the Assembly pics the speaker + and - go to the same place, pin 3 but in the final pic one goes to pin 3 and the other to pin 4. Which is correct?
I have made three of them so far and nun of them work properly. I had the same thing happen with one of mine as you have described. I was reading about the 555 it was stated that the 555 becomes unstable if the cap and resistor values are too high, in the attempt to get long low cycles IE 5-10 minute range.
Also you need to watch what 555 chip you are using some of them can not sing as much current as they can source some only will sink 10 ma this i got from off of the data sheet for one of the ones I used.
Same thing i read
Sorry. The buzzer should be wired with the positive terminal going to pin 4 and the negative terminal going to pin 3. I will make corrections as soon as I can.
holidayv1 year ago
mine doesn't beep, it clicks. also, it clicks about every 30 seconds. what am I doing wrong?
person%2 years ago
you could stick one inside someone's computer. nobody will even think about opening up their computer or laptop unless they get so pissed that they separate every single object at their workplace.
White_Wolf2 years ago
I need something this small to locate my RC when it flies out of sight. If I were to add a push/pull transistor circuit to this, would it be louder or would I have to use a small speaker? I spent two hours looking for it today in the trees only to find that it must have autopilot. It some how missed all the trees and landed by itself in a cow pasture about two hundred feet away. WHEW! I can't tell in the video just how loud it is.
Thanks
:0)
You could use this project but it would be easier to just hook the buzzer up directly to the battery or to connect it to any extra channels that you might have open. Using a transistor shouldn't affect the volume much, especially if you use a supply voltage above 4.5
ijudson2 years ago
i finished mine and turned it on and it just continued to beep constantly is it because i used a 35v capacitor?
DIY Hacks and How Tos (author)  ijudson2 years ago
No. As long as the capacitor is rated above 4.5 volts, the capacitor voltage has no effect. Check for any shorts that might be grounding the negative terminal of the buzzer. If you are still having problems, send me a personal message and I will try to help you work it out.
ok ill try it out thanks a lot
ijudson2 years ago
i did also pay attention to the fix in the schematics and triple checked all the wiring and nothing is is wrong with the wiring
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