[TowerTalk] Bye Bye Birdies

Sat Jan 5 12:43:26 EST 2013

I bought two kinds of COTS equipment. One was from Sharper Image catalog. I 
don't recall the other. This was over 20 years ago.  I helped a friend build 
a system subsequently using Radio Shack piezo-electric horn tweeters which 
we drilled for drainage.  This too was 20 years ago. We bread boarded a 
signal source using 555/556 timer chips and small power amp.  I don't recall 
the ckt exactly but could recreate it probably from an old Signetics 
applications manual if provided a copy (mine faded into oblivion years ago.)

This isn't rocket surgery or brain science. You just want an ultrasonic 
signal high enough in frequency to not be heard by humans, say at least 
22-23 KHz (I used to hear up to 21.5 KHz, yes I could hear ultrasonic 
alarms, bats feeding, etc.) and loud enough to be terrifically annoying to 
birds.  Don't waste power with freqs above the tweeter's capability (maybe 
30-35 KHz) I haven't looked into tweeters for ultrasonic reproduction for 
decades but expect them to still be readily available. A simple BUT LOUD 
ultrasonic signal ramped up and down annoys birds.  One way to get the 
signal is a VCO ckt modulated by a sawtooth generator (see application notes 
for 555 and or 556 chip) Feed this into an amp capable of a few to several 
watts (you don't need mega watts to annoy birds) thence into efficient 
speakers with ultrasound capability (used to be cheap at Radio Shack as 
Hi-Fi tweeter horns)

Additional sophistication is to use an IR motion detector to turn the unit 
on (like a security light ckt energizing your power supply. It worked for 
cats and dogs but isn't always reliable for birds. At least the ones I tried 
(way back when) were not always sensitive enough for small birds.  Larger 
birds will likely be "seen." Here is where you look into circuits like those 
used for safety purposes on your automatic garage door opener.  If you break 
the LED beam you are detected or put another timer stasge in it and have it 
turn on for several seconds then off for a while and back on.  A duty cycle 
of say 10% should be plenty say on for 6 seconds and off for 54 or whatever 
you like. The trick is to not just turn it on for long periods as the 
feathered nuisances can get used to just about anything steady state. 
Something coming on LOUD every little while has a good startle effect. 
Pseudo random sequence would be terrific if your skill is up to it.

Need more info?  Try Google first then if you really are stuck for ideas, 
ask here again.

Patrick

-----Original Message----- 
From: Grant Saviers
Sent: Friday, January 04, 2013 7:26 PM
To: Patrick Greenlee
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] Bye Bye Birdies

Patrick

Please suggest some stocking suppliers and models.

Grant KZ1W

On 1/4/2013 10:52 AM, Patrick Greenlee wrote:
> Plastic owls and rubber snakes work for some folks but are not universally 
> successful.
>
> Ultrasonic emissions have a much higher success record. Ultrasonic waves 
> are easy to "beam" directionally which permits a ground or near ground 
> level installation with the transducer(s) aimed up to where the birds like 
> to perch.  Aiming the sound upward keeps from disturbing the dogs and 
> cats.
>
> These devices are available COTS for relatively little money or easily 
> built by the electronic savvy. Mine have lasted for many years and still 
> work well.  Some of these devices offer choices on the type of output.  A 
> randomly occurring warble tone similar to the "yelping style" public 
> safety sirens (but of course in the ultrasonic spectrum) seems to work 
> best. Having it come on at random intervals works best and keeps the birds 
> from getting used to it.
>
> Inexpensive "tweeters" of the horn variety work well, especially if the 
> design lends itself to accepting a drain hole for water (well... it is 
> aimed up) Alternatively an enclosure with a hard flat reflective surface 
> to aim the beam upward will work.
>
> I have used these for many years with great success, not only for birds 
> but other pests as well when coupled with IR motion detector including 
> cats and dogs who used to think my yard a public restroom and the odd 
> skunk, raccoon, armadillo, or opossum.
>
> Patrick AF5CK
>
>
>
> iginal Message----- From: Jim Lux
> Sent: Saturday, December 29, 2012 5:16 AM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Bye Bye Birdies
>
> On 12/28/12 9:11 PM, Bob K6UJ wrote:
>> Another option for bird control is to get one of the plastic owls and put 
>> him up on the tribander.
>> My results were negative, evidently the birds in our area aren't scared 
>> of owls because the owl didn't help at all.
>> When i took it down I discovered the birds had crapped all over it.   :-)
>>
>
>
> my in-laws experience with their vineyard was that birds are discouraged
> by novelty and change.  reflective ribbons one week, owls the next, etc.
>  That doesn't lend itself to antennas
>
> the other strategy which seems to work quite well is to make what ever
> it is "not sittable on".  those funky plastic spiky things or
> string/monofilament.
>
> Of course, neither of the latter are particularly easy to do on
> something like a multielement beam, especially if you want it to last
> for decades.
>
> For ordinary wire antennas.. I suppose, if you use strong enough copper
> clad steel, the birds can just sit on the wire forever.
>
>
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