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Transmit audio to a receiver on a mast to scare birds

Discussion in 'Audio' started by TonyS, Jul 13, 2010.

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  1. TonyS


    Jul 13, 2010
    Hi, I am new to this forum but need some help.
    On our marina we have a problem with birds perching on the top of masts and making their mess on the deck below. I have had success with a mole scarer that emits a 500Hz pulse (buzz) for a few seconds every minute. It is hoisted to the top of the mast and the birds don't like it and go elsewhere. However it is overkill and sounds 24/7 and annoys us and the neighbours when they sit out in nice weather.
    I want to use a transmitter from the house, nearby (50m), to send a pulse of sound that switches the receiver on the mast out of sleep mode (low currrent drain from internal battery), passes the audio pulse (2-5 secs duration) to an amplifier and loudspeaker. I can then control the transmitter to come on for a couple of hours at dawn and an hour at dusk (the worst times) or when we see birds there.
    It could be based on PMRs from Maplins or their 433Mhz Transmitter Receiver modules. The PMR approach would probably use too much current (I want the battery to last 1-2 months) but the TX RX modules look good as they sleep but how can I make them transmit and receive audio? Or is there another approach. Any help or ideas would be much appreciated.
  2. shrtrnd


    Jan 15, 2010
    Just and idea.
    Birds don't fly at night, so you don't need to power your existing set-up 24/7, turn it off
    at night. Put a timer on it, so it activates at dawn and dusk (your worst times),
    I know you're looking for a new set-up, but I'd try working with your present system (that you said works well). Other than that, you'd have to research what frequencies annoy the birds, and not the people you're presently annoying.
  3. TonyS


    Jul 13, 2010
    Thanks for your reply. I have also thought of your idea. However, there are a number of points.
    1. Dawn and dusk change continuously. This is only a solution if it can be left for weeks at a time to operate.
    2. I don't know how to design a timer that would be programmable for 2 periods of say 2 hours and also work off microamps so that batteries last at least a month. I know that I could have a solar cell to charge them but the circuits start to get beyond me. Could I buy a cheap electronic mains timer and convert it to run off a 6V battery.
    3. The idea of using a TX RX was that I could experiment using different frequencies, waveforms, power levels etc to visibly see what makes the birds jump. A clap of the hand works as also does banging the shrouds making everything shake at low frequency.
    4. Whatever I use has to be small, fairly robust and waterproof so that I can attach it to a flag stick and hoist it 20m up to the be just above the mast top where the birds perch. Clearly a noise very close to where they perch doesn't have to be very loud to annoy them. The buzz from the mole scarer works by its persistence. After 2 - 3 cycles they fly off.
    5. I have tried ultrasonics which doesn't work nor does hoisting 20m of cable for an external supply.
    6. I have been experimenting for a few years as have others to overcome this problem and the TX RX idea I think is the best, at least to find the best sound and duration.
    7. When I have this info I can try proximity detectors to set it off, if birds trigger proximity detectors and these can cover all directions and not be set off by movement created by the wind.

    I was hoping there might be some expertise of an audio TX RX where the RX is in a sleep mode until a signal is received. This could be adapted from a commercial product.
  4. NickS


    Apr 6, 2010
    The San Diego Pier uses silent spikes attached to the top of perching zones. They do the job silently 24/7

    Attached Files:

  5. davenn

    davenn Moderator

    Sep 5, 2009
    yuo they are getting very popular , NickS, specially the plastic variety some of us Ham's are using on our radio antenna to keep the cockatoos from wrecking them.

    Tony, with the other buzzer you have use it up the mast you know it works.... you dont have to send the audio via the 433MHz radio link. just use the radio link to turn on and off the the buzzer as needed. rather than a power using timer you could use a LDR or photo-transistor to auto operate the buzzer at dawn/dusk that would give you the daytime nite time separation :)
    You are not looking for absolute accuracy with turn on turn off

    my 3 cents (2 cents + inflation) worth :)

  6. TonyS


    Jul 13, 2010
    This is a picture of the top of the mast of a sailboat. The devices you show are for pigeons or larger birds - where they are effective on flat surfaces. The problem we have is with starlings who can sit on thin vertical wire.
    There is also the problem of getting up the mast to do anything.
    You can see the problem of hoisting even a flagstaff so it protrudes above the mast and doesn't foul the lights, wind indicator, aerial or instruments.
    That is why I am seeking an electronic/sound solution.

    Attached Files:

  7. TonyS


    Jul 13, 2010
    I have tried to use an LDR with a solar mole scarer that worked off 3V but found it too difficult. The advantage of the solar powered charger was that there was space inside the sealed package to incorporate a few components. The 6V device has 4 D cells which take all the space.

    I find the buzz of these devices annoying on a still day. I want to experiment with making different sounds/ amplitudes/frequency and duty cycle without having to go to the boat and spend 20 mins getting the device down and the same to put it up every time I want to change a parameter.

    However, the final device, for which there may be a market for several thousand, could be self contained, solar powered with pre set timers etc.

    You have given me an idea. Could I use one of the digital TX RX links that sell for $20 (£10), and transmit RS 232 to switch on and then off by relay an analogue RX of an audio TX RX link that the Rx from literature, without amplifier, consumes about 25 mA. Is this the best option. Could anyone recommend one of the attached or am I looking at the wrong product. I also need to know how to program it and connect it to a suitable relay.

    Attached Files:

  8. NickS


    Apr 6, 2010
    Sorry I couldn't readily find a good picture of what I wanted. The ones I was actually talking about are a group of long individual spikes set in some sort of epoxy. It deffinately looks like a home brew job even though they are all over the place. And I don't think even a small starling wants to perch on the end of a skyward spike, but I have benn wrong plenty of times before.

    As for getting up to the top, I am wondering how you would service your instruments up there if you are unable to ascend?

    No matter it looks like you are set on noisemaking. Personally I would find a way to get my circuit up on top and just make it motion triggered, assuming the tiny birds give off any good IR radiation.
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    NickS: putting spikes on a mast may be detrimental when you need to use the mast for what they're intended for :)

    TonyS: As long as range is not an issue, there are a number of 433MHz transmitter/receiver units that you could use.

    There may be several tricks:

    1) what is the quiescent current of the receiver? Will it flatten the battery too quickly?

    2) Can you add an external antenna to the receiver to increase the range?

    3) How will you encode a signal so that (say) someone opening their garage doesn't start your device?

    4) Do you want it to be ON/Off (2 signals) or ON for some preset period (just 1 signal) -- or even a combination of both.

    You may be able to find modules already set up to do what you want. If not, it comes down to your level of skill.

    I would probably use a PIC or PicAxe so I could program whatever *exact* operation I required. Even if the task was simple, the PIC solution required very few components (probably). However that may not be the best or easiest option for you.

    If you want to control more than the simple on/off state, then I would almost certainly look at a pic.

    If you google for "433MHz picaxe" you'll find an awful lot of quite simple circuits and programs. Maybe they can give you some more ideas.
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