And all that is driven by a simple pair of 555 timers, one for the carrier and the second as an FM modulator. The emitters are driven in parallel though through individual LR networks by an RC-snubbed inductive flyback voltage booster which is switched by a single high voltage n-channel depletion-mode MOSFET which is, in turn, driven by a well-bypassed high-current MOSFET gate driver. But since I didn't want the system to produce a too-focused and directional beam, the emitters being spaced several wavelengths apart will result in a wider dispersion. And since you really don't want to be anywhere near this thing - especially not in front of it when it's activated - I included a 500-foot (nominal) range, single-channel, 315 Mhz RF remote control that can be used to either trigger a fixed 4-second blast, or operate the unit in On/Off Toggle mode.įor audio power generation, I used four synchronously-driven high-power handling, piezoelectric horns which will produce phase-coherent wavefronts. Since Mark's application need was for more of an "installation", I chose a configuration that is less a "sound gun" and more of a "deterrent outpost". So I picked up where I had left off late last summer and completed the first working model of what developed into an unbelievably loud super-sonic acoustic blaster: and the yappy little shit was back at it again! He told me that he had recently been awakened at 2:30am, and that it was becoming a problem. I was hanging out at Mark's house a few weeks ago, helping him set up a new Windows 7, 4-channel CableCard Media Center HD recording system. So I after pursuing the design of a second-generation device, I switched my attention to other more pressing work without ever needing to push the theory all the way to practice. In the case of the resurrection of this infamous "Portable Dog Killer" project (which was renamed to "Portable Sound Blaster" in recognition of the fact that we're no longer 15) my best friend's troubles with the wayward "dog next door" had abated for last year. As people who have known me and followed my work for many years know, I have so many various irons in the fire that I shift my work-priorities when the associated need-priorities change.
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