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How to turn Smoke alarm into Ultrasonic Dog Repeller

Discussion in 'Audio' started by ArtJ, Sep 26, 2018.

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  1. ArtJ


    Sep 26, 2018
    I am pretty new to all that stuff.
    So far have experimented with 555 at 10-25kHz, but the dB is too low. Even at 10kHz the output power is pretty low (measured by my Samsung app, OScope at distance 2-4 cm it's just a few dB). I am using a piezo transducer from an old sound system).

    My question : Is it possible to turn an old smoke alarm into a Ultrasonic Dog Replant?
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Was the dog planted previously? My gardening experience tells me that you should probably use a bigger pot when you replant it.

    Perhaps you mean repellant?

    Do you know what repels dogs? I don't. When one of our smoke alarms goes off it annoys the heck out of me, but the dogs just ignore it.
  3. ArtJ


    Sep 26, 2018

    Apologizes. Not Replant. it is REPELANT, Dog Silencer
  4. ArtJ


    Sep 26, 2018
    Any way that I can edit the title? From Replant. to REPELANT, Dog Silencer
  5. ChosunOne


    Jun 20, 2010
    I assume you mean an Ultrasonic Dog Repellent?

    10-25kHz isn't really ultrasonic--most adult humans hear up to 20 KHz, and most kids well into their teens hear up to 25 kHz ( and many of them beyond).

    I seriously doubt that that an old smoke alarm sounder can be modulated to sound in the ultrasonic range. In the USA, the high-pitched piezo sounders (as opposed to the older raucous buzzers) sound a lot like a Mallory SC628 Sonalert piezo sounder that operates at 2.9 kHz. Given that (as I understand it), that frequency is governed by a crystal integral to the sounder, I doubt it can be boosted up into the U/S range.

    EDIT: Sorry, I didn't see your corrective post before I posted.
    And an ultrasonic dog repellent is likely not to be a dog silencer--I suspect that dogs that have to endure it (i.e., can't escape it) might be noisy in their protests.
  6. ArtJ


    Sep 26, 2018
    Hm, it doesn't sound promising.
    Any chance of replacing the whole sounder with a small piezo (80 dB) I guess the impedance will be pretty similar so the amp wont struggle with the capacitive load?
    Then uplifting the output frequency to 25 kHz ( the best freq to silence dogs)?
  7. Bluejets


    Oct 5, 2014
    I don't know........our cat took one look and disappeared for 2 days the last time my burglar alarm went off(same sound) ...last I saw him he was about 300m away taking a look back to see what the hell was that//

    Guess I should add in fairness, he was in a deep sleep in the middle of the day at the time :)

    Then again, dogs seem to have attitude and you're likely that the response will be he don't give a fug.

    I have seen where old smokies are hacked ( fairly simple) for use as water level alarms.
  8. Audioguru


    Sep 24, 2016
    A piezo transducer is made to produce audible beeps, not ultrasonics.
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