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Topic: Thoughts on automated ways to make a loud "crack" sound? (Read 552 times) previous topic - next topic

kjmclark

I have a project I'm working on at our farm, combining PIR sensors and something that will make a loud noise.  The goal here is to scare wild turkeys.  We have quite a rafter of turkeys all-of-a-sudden, and I'm really concerned about them eating everything in sight come spring.  I'm working on lots of other things, but this particular one has me a bit stumped.

I'm aiming for a sound kind-of like a .22 - so loud enough to freak out the turkeys, but not loud enough to freak out people in the area.  (There are lots of people shooting guns off out there, so a .22 wouldn't be a problem.)  I'd like to be able to repeat the sound if the turkeys come back, but I wouldn't want it to be continuous, or even more than a few cracks per triggering event.

Two things I've thought of, and may do at some point for this part of the problem are 1) make a propane sound "cannon", and 2) make a large Marx generator.  The propane cannon I'd like to wait on, because the farm has neighbors, and I'd have to go to a lot of lengths to make the thing, only to have to make sure it gets used *rarely*.  Those are supposedly not hard to make, but not popular with people, and since this will be unattended, I'd need to put lots of safeguards in place.  Those vary in sound from a 20-gauge shotgun to literally like a cannon.  Ouch.

The other option, I think, is a Marx generator.  I have a few concerns about that
  • It wouldn't be loud enough
  • I only have 12 power at the farm to work with
  • They're also fairly dangerous, so I'd need to shield it a lot
  • While it looks pretty easy to set up, I'd have to give lots of thought to MOSFETs vs. relays for that.  Seems like one of the many good ways to burn out a digital out.

I have thought of speakers, but I'm not seeing a good way to make a sound like that well with speakers.  OTOH, I'm not an audiophile, so maybe that would be easy and I don't know it.

So, the question is, can anyone think of a good way to make a nice, loud "crack" sound, that's relatively easy to automate with an Arduino, that's relatively safe, and that I'm not thinking of? 

Thanks for any thoughts.

kjmclark

Oh, here's one.  https://www.ebay.com/itm/100pcs-lot-11-81in-Electric-Igniter-Electric-Match-for-fireworks-firing-system/132287032256?hash=item1eccebebc0:g:lQsAAOSwTvpZb6yt

Never heard of these before.  Apparently, you apply 12V to one of these, and it lights a small igniter, which you've attached to some kind of firework.  I guess they use these for professional fireworks shows.  So, if I attach the other end to the wick of a firecracker of whatever size, I can get an automated firecracker system, which will do nicely.  The only problem then is coming up with a system to multiplex out 12v power to a bunch of these, in sequence so you're only firing the next one in line, and some kind of safe containment for the whole thing.  Those are feasible.

Gabryx

Is more simple eat all wild turkeys....joke...but if are already many people that use weapons, i think also this wild turkeys is not so scared...so eat eat eat
https://www.youtube.com/watch?v=hDuxyhfchYg
https://www.youtube.com/watch?v=hyIqT0kAdVo&t=750s
https://www.youtube.com/watch?v=kw-r1wts60Y

CamJackson

Have a look at this device:

https://www.ebay.com/itm/Bird-Wildlife-Scarer-BIRD-SCARE-Propane-Scarecrow-Electronic-Cannon-SOLAR/172320928274?hash=item281f20b212:g:~5MAAOSwZVlXwdY7

MarkT

You have no need of high voltages, a large electrolytic capacitor at low voltage will make an impressively
loud spark too.  A servo-operated contact set could be used to close/open the gap (at low voltage you
have to bring the contacts together).

The contacts need to be beefy as they sustain damage every time they are operated, and may weld together
so good leverage will be needed to guarantee separation each time.

But an even easier approach (simple cheap parts), is a weatherproof horn speaker, audio amp and an audio sample player.  You can change the sound and volume and experiment.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

kjmclark

Sorry all who replied.  Getting back to this.  Some replies:

Gabryx - that would be a great solution, except for that "poaching" concept, which leads to "fines" and maybe "jail".  Seriously, in the spring you can kill one turkey.  Period.  One.  Also, has to be a male.  In the fall, you can take as many as you have licenses for.  But I need to keep them away from crops from May to September.  Spring hunting season is in May, fall hunting isn't until September/October. 

Cam - yes, thought about propane cannon.  Actually, I got a voltage booster and a car ignition coil to eventually build one of those.  But that's a ways down the road, and they're way too loud to use often.  I could probably make it quieter some by regulating the amount of propane before ignition, but it's going to require some work and experimenting.

Mark - that was the concept for the Marx generator, with no moving parts, but you're right, now that I've worked with servos a bit, it's not that bad.  And the speaker is something I'm working on now.

What I settled on is a combination of a few things.  Still working on assembly.  I bought a creepy scarecrow Halloween prop.  I'm putting him on a swiveling platform, with a lazy-susan bearing, and a stepper motor to turn it.  I'm using a couple of PIR sensors to detect movement.  Turkeys are only sometimes noisy (the scarecrow is sound activated), so I'm putting a little piezo speaker next to the microphone on the scarecrow to fire when I need to.  I'm also setting him up with a FM radio chip, and a waterproof speaker and audio amp.  Finally, I bought some nice mosfet/shift register boards, some push-in wire connectors, and those fireworks igniters I mentioned above.

So, there are all the parts.  When the PIR detects something, the stepper will turn the scarecrow to center, then toward the sensor that detected movement (the scarecrow can swivel freely when the system is powered down).  The audio speaker, with a local NPR station tuned in, will start broadcasting people sounds.  If I get another detect within a minute or so, I fire off the piezo speaker to get the scarecrow moving and making its own sounds.  (Check the video on that thing, it's creepy.)

Finally, if I'm still getting detects after another minute, and it's between certain hours, and I haven't fired one off today, I'll use the mosfet/shift register boards to fire one of the igniters.  The igniters will be connected to firecrackers installed in a set of short (~3"), open pipes and covered with aluminum window screen.  I've tested that arrangement, and it works great.  Nice loud "crack", pipe section keeps stuff fairly safe and sound pointed away from neighbors, window screen catches any flying firework parts and keeps fire risk down.  I think that arrangement will be about as legal as the propane cannon, without upsetting the neighbors too much.  I check every week or two to see which fireworks have gone off, and replace them. 

The other nice thing about that set-up is that most of that system will still be working at night - no fire crackers, but a talking, moving, glowing-eyed creepy guy, with loud human voices, will totally freak out deer that get too close.  Between that and the baited electric fence, I think I'll keep the critters out pretty well.

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