Smallest keychain security alarm?

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The hearing range on these devices depends on the height of the rocket and wind direction. When the rocket is high in the air and descending, you can hear the beeper from a long distance and determine the general area where the rocket is landing. Once the rocket is on the ground, you can only hear the beeper from about 100 yards away, or even less if the wind is blowing in the opposite direction.
 
And when using these types of locator devices one still needs to know ABOUT where the rocket landed to be able to get close enough to hear it.
These are great for crop fields for the last 50-100 feet to the rocket.

Then of course when it ends up in a tree one hears it all day.
 
Then of course when it ends up in a tree one hears it all day.
Mine went towards the trees last summer but without an audible device, we had no idea if it was up in the trees or in the 3ft tall grass in front of the trees, and it has never been found. 😩
 
I have had my mailbox broken into a couple of times. I put one of these alarms in a small package with an hole cutout for the alarm speaker and anchored the pull switch cord to the mailbox, so next time someone breaks in and steals that package they will get a surprise. Not sure that I would be able to hear it from in the house, but if anyone happens to be on the street nearby it might attract some attention. Not quite as sophisticated as Mark Rober’s glitter bomb fart spray decoy package, but maybe it will have a small annoying effect on the next mailbox vandal and package thief.
 
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Consider the ViFly beacon, made for finding drones. About an inch long and 5/8ths cross section, 6 grams. Not as loud as some, but lasts a LOT longer than personal security alarms. The 'crash' logic is readily satisfied in a model rocket (like a JLSR, gotta remember to turn it on).

https://viflydrone.com/products/vifly-beacon-drone-buzzer
Cheap 3 packs on Amazon. I made a bridle of high strength cord (Kevlar or Nomex thread would be ideal), snaked through the heavy-gauge shrinkfit housing and tied in a loop. Leave the loop long enough to easily pass the beacon through, and you can attach it by looping it around the shockcord or any convenient ring or loop (forming a Larks Head/Cow Hitch).
 
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