About a year or two ago I discovered an iPhone app called “Sound Grenade“. It produces a very high frequency sound that is very irritating if you can hear it. I am fortunate enough to not hear it, so it was fun turning it on and watching those around me squirm and squeal about that awful noise and trying to figure out where it was coming from.
I recently began to wonder if a “sound grenade” or “high-frequency” sort of device can be made using simple electronic components. FYI, the frequency range begins at 8Khz, then progresses to 10Khz, 12Khz, 14Khz, 15Khz, 16Khz, and 17Khz. A video demonstrating this range can be found at http://youtu.be/LNjPmhbPc9I. After much research, I discovered such a circuit can easily be built using the 555 Timer and a small 8-Ohm speaker. I’m not sure what the full range is on this since I cannot hear the sound above a certain range and my wife is unwilling to help since it’s very discomforting to hear. I also do not have an oscilloscope to test it with.
QUICK NOTE: This does NOT have a pull-pin or a delayed timer to it nor is it designed to be thrown like a real grenade. The app doesn’t either and so the idea was to imitate the app’s behavior. For that type of project, you might have a look at http://imakeprojects.com/Projects/sonic-grenades/ or http://www.instructables.com/id/Sonic-Grenade-from-Mostly-Scavenged-Parts/.
- 1 – 555 Timer IC
- 1 – 8-ohm Speaker
- 1 – 9V Battery Snap [Hard] or [Soft]
- 1 – 1K Ohm 1/4W resistor
- 1 – 10K – 100K Potentiometer (Any between this range should work fine)
- Custom PCB or a Breadboard
- 1 – 0.01 uF Capacitor (103)
- 1 – 0.001uF Capacitor (102)
- 1 – 9V Battery
Project Cost: $5 or less
If you need the circuit layout for etching your own PCB, here’s the one I’ve made: