Centre tapp transformer

[chrisalang]

I am building a cercuit to produce a high power 20MHz sound to stop a neighbours dog barking. I have tried a commercially available device and it is useless. I need to build a transformer with the following characteristics:

Primary 150 turns 28 SWG
Centre Tapped
Secondary 40 turns 24 SWG
Core ferrite U type.

My question is where can I find a suitable core and does anyone have instructions of actually how to build it. Any advice on how to increase the power outpt appreciated.

According to the circuit diagram I have the output needs to be connected to a 5W tweeter.

Many thanks for any advice, the dog is driving us mad !!!

[Mooly]

I don't think a tweeter has much response at 20Mhz

Why do you need a coil/transformer to drive a 5 watt device ?

[Speedskater]

I'm sure that the the "20Mhz" was a typo and he meant kilo.
But I also think that Chris is in over his head and there are other easier ways of building this type of unit.

[chrisalang]

Hi Guys, thanks for the replies. Yes it is KHz

I will see if I can post the circuit diagram.

[chrispenycate]

Who designed that circuit? It would be easier and cheaper to do a complementary/mock complementary - hey, you don't care about the distortion, use a switching circuit, drive square waves into it, and assume the harmonics are not going to be reproduced by the driver. A five watt amplifier is not that difficult (finding a tweeter that can take five watts of 20k continuously might not be as easy as it seems), although you might have to bridge it to get the power into a medium impedance tweeter from twelve volts. Still cheaper than building the output transformer; that's tube mentality.

But, in my experience, dogs start to bark when they hear high frequencies, not stop. If you had a bark detector circuit, which applied an aversion shriek every time it heard the dog, I could understand the philosophy, but as it is, just "turn it on and make the beast unhappy", I don't see how it can learn that it's its own actions that are triggering the discomfort.

But

[chrisalang]

The circuit was from a web site but I can't remember where. It is not on continuously but will be linked to a detector and relay (like a clap detector) so the circuit will only emit a high frequency in response to the barking. The idea is that the frequency is not liked by the dog so the dog is conditioned - provided it is not deaf of course. Sorry for not making it clear.

[Mooly]

Woof
PRO POWER|GUBCB|ULTRASONIC BARK CONTROLLER | CPC