Ultrasonic Sound Emitter (For Dog Control)

Projects General Guidance
1

Ok, so I'll start with some project context.

My dog is really well behaved in almost all senses, except when the mailman comes'a'knocking. In these instances he will bark, bork and berk until my neighbors ears are bleeding. This is a problem, and I enjoy using Arduino to fix problems.

I want to create a wireless module I can place by my door, that is controlled via sound sensor or by a smartphone app that I can use to startle the dog with a high-power ultrasonic sound.

That smart phone and comms element will be fairly simple and I shouldn't have much trouble sorting it. Where I am some what perplexed however is the implementation of the 40khz transducer required for the noise.

I purchased one of these: Arduino proximity sensor

My understanding is that this board has two simple 40kHz transducers which I can de-solder and implement in my own circuit, is this true?

I was also wondering how to control the volume of the noise? Does anyone have any ideas regarding voltage etc.? Would I need to (complete noob guess) insert a 40kHz crystal to produce the right kind of modulation?

Thanks

Guy

2

40khz is way above the hearing range of a dog. You need something around 15-20khz.

Weedpharma

3

weedpharma:
40khz is way above the hearing range of a dog. You need something around 15-20khz.

Weedpharma

Early TV remotes were using 40kHz transducers.
I knew a dog that went crazy when you used one.
Leo..

4

A few years ago, I made a manual barking deterrent sounder set to 25khz, worked quite well.

.

5

Thanks guys,

What power do you recommend putting through these transducers?

40kHz should be within the hearing range of a dog, I think their hearing caps out at 45-46kHz

I take it I can't just put DC into it, needs to be a mix of on/off in order to make it vibrate right?

6

Guy123:
I take it I can't just put DC into it, needs to be a mix of on/off in order to make it vibrate right?

No, you have to feed it with 40kHz, not DC.
And the peak/peak voltage has to be high enough to be effective.
Just 40kHz from an Arduino pin might not do (volume wise).
You could try with this sketch. See if your dog reacts to that.
Leo..

const byte whistlePin = 11; // connect transmit transducer to pin 11 and ground

void setup() {
  pinMode (whistlePin, OUTPUT);
  TCCR2A = _BV (COM2A0) | _BV(WGM21);
  TCCR2B = _BV (CS20);
  OCR2A = 199; // ~199 should produce 40kHz
}

void loop() {
}
7

I don't think you'll get enough volume for your purpose just using an Arduino to drive the transducer. The HC-SR04 uses a MAX232 chip to boost the voltage level, and I suspect that even that volume might not be enough. It's got to be loud enough to annoy, not just to hear.

Still, for testing that's not a hard thing to set up. You might need to send short bursts close together though, for the MAX232 to work properly. This is the schematic:-

HC-SR04 Schematic.JPG
HC-SR04 Schematic.JPG1151×782 79 KB

Ultrasonic transducers are typically rated for a fairly high voltage, about 50Vp-p or more, from memory. Rather then the MAX232 method, a H-bridge with a decent supply voltage might be needed to drive the transducer at a good volume level, with the Arduino driving the H-bridge at 40kHz.

8

Try it, and let me know how it works out.
I've been thinking of just buying a proper ultrasonic device (like those ineffective wall-plug rodent repeller ones) and just controlling that via relay.

Anything that needs to be loud will benefit from being powered from the mains.

9

Looking up the range has taught me something! :disappointed_relieved:

Weedpharma

10

I was also looking to increase power to the transmitter of ultrasonic range sensor (HC-SR04).

It seems the voltages specified are never consistent among sellers, I've seen values of 20, 30, 60 and 120V in various pages.