Sonic Grenade

sonic grenade started recently with the promise of delivering one project every two weeks. Yesterday was their second release: sonic grenades! They picked up a couple 110dB personal alarms at the Dollar Store and modified them. Now instead of going off immediately, there is a 5 second “fuse” indicated by a flashing LED; giving you plenty of time to lob it into your roommates space. After a minute of being active, the grenade will start chirping every 10 seconds until you replace the pin which should help you find it. There’s a video demo at the bottom of the page.

[thanks JErome]

30 thoughts on “Sonic Grenade

  1. Personal alarms are promoted in areas with possibilities of rape. For instance an all girls school downtown in my hometown gives one to each of their students because the area can be dangerous at night. They are MUCH louder than that makes them seem. And hurt your ears pretty bad, I hear if held to your ear some can make you temporarily deaf, and even cause some permanent damage. So make sure to test how loud it is before you open it in your friends ear. ;)

  2. Pretty sweet. And the pic code looks easy enough to modify without knowing how to code it. Not only is it useful for this grenade, the code provides a way to create a cricket. (A cricket is basicly the last bit of the code that it chirps fast with a delay inbetween. Limit the volume a bit and change it from a 100 msecond chirp to maybe a 75 ms and the 10000ms delay to about a minute. Then turn it on and place it in someones room. It drives people crazy because it chirps and then stops, so it doesnt chirp long enough to track it right away. Hell, its a pic, so you could change the code to create one that changes the delay according to a light sensor or another input, or random number generating to pic a delay, making it near impossible to find) For example:

    Also, you can add more then one in a grenade to make it annoying. My addition to the project would be adding another pierzo speaker and include a small increasing chirp (And increasing led) for the timer instead, much like what digital cameras use for a timer (Think 1 chirp/flash, 3 second delay, 2 chirps flash, 2 second deley, 3 chrip flash, trigger main alarm)

  3. Pretty cool and fairly inexpensive. I must say though that if these had an actual voice chip in them they could be programed to count down before “detonation” ala R.A.Heinlein’s talking grenades:
    Come to think of it since it is such an old idea and so cheap to manufacture I am surprised that they haven’t been used by our psy-ops boys? (Thinking on that it may be because every extra ounce carried into battle that isn’t a weapon or ordinance is an ounce that will drag your ass down.)

  4. WHAT would psyop people want with that?
    I think the enemy would just laugh at you.
    Those cheap alarms work good as boobytraps though. Alot of roomates use them on their food, beer, cds etc.

  5. you know what else this could be used for i did this one i saw this at like 7 in the moring i just so happend to have most of the parts so i got to work. and well now i am just letting every thing dry but anywho i put the pin on the inside of the bottle and guled it to the lid. so when they open the bottle it goes off. but i went a step more and made it so you can’t put the pin back in right away. its got a spring loaded door made from a old race car set trigger…that when you pull the pin the pin also holds the door so when the pin is gone the dor closes the hole. so you have to fool around with it.

  6. As cool as this is, we all must be careful with this type of thing. While we all know this is a harmless prank device, others do not. I hate to be one of those “now more than ever” people, but folks are a lot less laid-back about fake weapons these days. I dare say that running around lobbing beeping canisters into rooms might not be the safest thing to do.

    The last thing hacker/maker culture needs is another CNN headline

    I don’t really want to have to wear a “free Fragged” shirt…

  7. To answer poster #4, yes it will deafen you a bit and if you did that for a long time it will cause hearing damage. Now 110db is pretty loud. I’ve lost about 5-10% hearing in my left ear before from when I was at the gun range and it’s my bad for not having ear plugs then. I think those guns echoed about 150db.

    Well I tried one of these with cardboard and duct tape cause I can’t find any dummy nades around. Be careful how you prank someone with these things. I used it as a trip sensor for our stockroom at my work place and it scared the crap out of the lady who was carrying a lot of folders and a fresh hot pot of coffee (glass) when she tripped it. Suffice to say I took some crap over that and the glass shattered all over the place. >_<; This would be a good thing to have for friday nights when you're running down the dorms or room parties and yell "bells in the hole" and chuck it in and run.

  8. Ok, I figured out a lot of stuff on the 555 timer (I actually had a electronics lab book I “borrowed” from my college). And found out that the .01 uf capasitor is labeled 103. I am going to radio shack to buy a electronics board and see if I can rig this thing up. If you use a bigger capasitor the time delay will be greater. And I beleive there is a way to make it pulsate like a anoying chirp, by having a high and a lower (not a low, as that would be off i believe) voltage. I will let you know how it turns out.

  9. still cant get the darn thing to work. Is there a spicific 555 timer to use? I just picked up a few at Radio shack. I used Tweaqs diagram, and did it a couple of times and still nothing. I am still confused on where the buzzer goes. Were does the number 3 pin go to. I see it going to a different + sign. Where does the siren hook up ? Please help me someone as I can put this to use very soon.

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