Miniature Beeping Circuit Prank

About: 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, and all around Mad Genius

Intro: 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.

7 People Made This Project!

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99 Discussions

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lferrelld

5 months ago

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

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LimitlessD

Question 6 months ago

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

1 more answer
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DIY Hacks and How TosLimitlessD

Answer 6 months ago

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

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MarkS-H

7 months ago

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

555.JPG
1 reply
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DIY Hacks and How TosMarkS-H

Reply 7 months ago

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

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kevin.longeuay

3 years ago

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

7 replies
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CameronM37kevin.longeuay

Reply 11 months ago

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

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HeatherH174kevin.longeuay

Reply 1 year ago

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 ?

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CameronM37HeatherH174

Reply 11 months ago

Totally cool! Yes. The smaller the capacitor, the quicker the interval. I think if you sub a 4.7M for a roughly 68k res it should be much more frequently! Very creative and positive application of this circuit!

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kevin.longeuayHeatherH174

Reply 1 year ago

I didn't get around to trying it out but the 555 timer calculator that the author sites below seems to be a good way to figure it out. A 1muF capacitor theoretically has a frequency of 3.5 secs and a 0.2muF has 0.7 seconds, both of which you can find at radioshack. I'd say try both and see which works better

The easiest thing to do is use a 555 timer calculator like this one.
http://web.udl.es/usuaris/p7806757/555-calculadora/555%20Calculator.htm

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DylanH90

1 year ago

Is there a way that you could significantly increase the volume of the buzzer?

1 reply

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.

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miknight

1 year ago

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?

4 replies

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.

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.

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.

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miknightmiknight

Reply 1 year ago

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.??