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Ultrasonic speaker or ??

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by MrDEB, Apr 12, 2010.

  1. MrDEB

    MrDEB Active Member

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    Tests have showen that the "DEER WHISTLERS" that you mount to your car do not work very well. My hope is that the two sets of frequencies would cause a deer to run from the source of the sound be it 2-8khz and / or 15-20khz.
    It would be interesting to see how deer react to these cheap tweeters.
    That "TEST" is what I have planed in the near future.
    I first need to get a unit working.
    Maybe, hopefully be surprised that the deer run away.
     
  2. audioguru

    audioguru Well-Known Member Most Helpful Member

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    How will you attract the deers? With your tweeters?
     
  3. MrDEB

    MrDEB Active Member

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    Yea I will call the deer "here deer deer deer"
    We have lots of deer here in the city of Salmon. Last year I had a nice 3 point buck right out side my front door. My dog keeps an eye on the window in the door for when the porch light is triggered by ?
    You guessed it deer.
    When I get this new version running I will go out on the highway where there are open fields and lots of deer.
    NO I don't need to call them. They come to me because I post on Electro-tech.com.
    If I told them I converse with Audioguru they for sure would stampead --- LOL
     
  4. dave

    Dave New Member

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  5. audioguru

    audioguru Well-Known Member Most Helpful Member

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    There was a deer in downtown Toronto. It probably walked miles along a river valley. They shot it with a tranquillizer gun then took it back to the woods far away.
    There are many deer around my neighbourhood and they don't run away when they see me.
     
  6. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Deer aren't scared by ducks! :D
     
  7. MrDEB

    MrDEB Active Member

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    I was thinking mice or ??


    LOL
    Just get an IC in your hand and they will run!!
     
  8. mneary

    mneary New Member

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    Scare the deer with a recording of a 12-gauge pump?
     
  9. MrDEB

    MrDEB Active Member

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    you must be a redneck?
    deer here in Idaho know you don't gos a hunten with a 12 gauge!!
    it takes a a high powered rifle to drop an Idaho deer.
    That reminds me I need to buy my hunting license and put in for the controlled hunt for Doe. They taste so much better than a buck.
    got one the last two years, assassin style - in the head. Best shot was 150 yards uphill (that way you don't work so hard to retrieve) using open sights (303 Enfield).
    If it hadn't been for the bush the deer would have rolled downhill about 100 yards and into the truck.
     
  10. mneary

    mneary New Member

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    I'm not anti-hunting, but the only reason I would personally frighten a deer would be to keep it off my windshield.
     
  11. MrDEB

    MrDEB Active Member

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    As well as your cars grill and / or bumper
    A friend of mine from church visited California last year and got pulled over by the CHP (highway patrol) and almost got a ticket because he had a heavy steel deer guard mounted on the front .
    My friend told the officer to look at the license plates.
    No ticket. I guess in California heavy deer guards are not allowed. Maybe to much of an advantage if a collision with another car ??
    TRUE STORY
     
  12. audioguru

    audioguru Well-Known Member Most Helpful Member

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    I am a pretty big duck!
     
  13. MrDEB

    MrDEB Active Member

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    Here is my preliminary schematic

    Not real sure on the voltage reg being I never used a LDO reg before.
    The pic outputs the two separate set frequencies and whala the deer will either run away or come find out what all the commotion is.
    Found a push pull amp with a couple of diodes to bias the transistors but not real concerned about distortion?? or should I (cause problems with the transistors?
    Wish I could just build the amps with what I have on hand - 10 - 2n3055's and about the same of 2n2054's.
    any ideas??

    oh yea quack quack!
     

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  14. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Mr. DEB,
    You need an amplifier to amplify the 5V p-p (1.8V RMS) from the PIC to 12V to 15V p-p (4.6V RMS) to make a low level sound from your speakers.
    The push-pull output transistors have NO voltage gain because they are emitter-followers they actually have some voltage loss. With an input of 1.8V RMS from the PIC their output is only 1.2V RMS which is almost nothing.

    EDIT: Guess how much power into 8 ohms? Only 0.18W RMS which is almost nothing. The 8 ohm speaker has DC in it which is bad.
     
    Last edited: Apr 24, 2010
  15. MrDEB

    MrDEB Active Member

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    I forgot to add the capacitor to the 8 speaker.
    will look at a different design for an amp for the low level. The high level as well.
    I simed in LTspice and not real syre if ithey amplify. The current is higher?
     
  16. MrDEB

    MrDEB Active Member

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    This should work??

    added capacitor and changed amp layout
     

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  17. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Mr. DEB,
    Your circuit is missing two amplifiers. It has two transistors instead.

    One transistor conducts on the first half-wave of the signal which charges the coupling capacitor through the 8 ohm speaker which produces a CLICK sound. During the second half wave of the signal and all future waves of the signal there is nothing to discharge the capacitor so it remains charged and the speaker does nothing.

    The second transistor that drives the capacitance of the piezo tweeter performs the same. It makes just a single CLICK sound.
     
  18. MrDEB

    MrDEB Active Member

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    I made two amps - both one transistor amps (see last post w/ revised schematic.
     
  19. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Didn't you understand my explanation of why your "amps" will not work? The speakers simply make a single CLICK sound instead of a continuous tone.
     
  20. MrDEB

    MrDEB Active Member

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    The amp withj the capacitor/8 ohm speaker works now.
    Weather it actually amplifyes??
     
  21. audioguru

    audioguru Well-Known Member Most Helpful Member

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    A simple efficient amplifier is one transistor driving push-pull NPN/PNP emitter followers. It will amplify.
    Since you have a single supply voltage then a coupling capacitor is needed to feed a speaker.
    Since your supply voltage is 13V from a car then the power into 8 ohms is only 1.5W RMS.
     

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