AM Radio Switch

[daisy8350z]

Hi everyone

I am building a project that utilises the electronic fence part of an electronic dog collar to act as a trigger for an autonamous robot. The transmitter wire that is buried in the ground sends out a radio signal at AM 600 that I am able to listen to with an AM radio.

Does anyone have a circuit I can use that will recognise the radio signal when it proximity to the wire and activate a switch when it hears it ?

This is the product I am using but I am unable to adapt the dog collar to activate any kind of switch. Basic In-Ground Pet Fencing System - Innotek SD-2000

Thanks guys
Daisy

 

[DerStrom8]

Welcome to Electro-tech-online, Daisy!
This sounds like a great project! I just can't believe that the dog collar can't be adapted to activate a switch. Have you tried taking the whole thing apart yet? There must be some kind of switch already that triggers the output of the collar. You should be able to remove (or at least disconnect) this part and replace it with a relay. I'm not sure how they make these collars now. I've heard that some actually shock the dog, which would require a step-up transformer to increase the voltage. I've also heard that some just vibrate at a frequency that really disturbs the animal. In the transformer version, I expect the wires to the driver circuit of the transformer could be connected to the relay, instead. In the vibrating type, there's probably a motor. The wires could be removed from the motor terminals and connected to the relay.
Anyway, good luck and keep posting!
Der Strom

 

[MikeMl]

The in-ground dog collar wire radiates at about 30kHz. The "receiver" is just a resonant coil which couples inductively; it is not a "radio", more like a transformer

 

[daisy8350z]

Hi DerStrom. Thanks for the welcome.

The collar unit itself is just as MikeM has described. There are no wires, switches or relays in it. It is all microprocessor controlled and surface mounted components, none of which I have measured as having a change in voltage when the collar begins to electrocute the dog.

But I am able to hear the signal generated by the wire on AM 60 or 600. What I need is an AM radio receiver at about AM 60 / 600 that once it receives a signal over a particular strength activates a relay or transistor.

I now have 3 dog collars that are in a hundred pieces, 1 left, and I am still no closer to making this work.

If anyone has another way to tell a circuit where the border of an area is I am all ears ! The wire in the ground method seems to be the best for my application (a farm paddock) if I could just get it to work.

Thanks again guys

 

[MikeMl]

If you tune around on am radio (540 to 1610KHz), you will hear harmonics of the oscillator in the dog collar transmitter, but they are very weak compared to the energy at the fundamental frequency. If you really want to use ~1MHz for signaling, you will need a different transmitter. To get a sensitive receiver, start with an AM broadcast radio. You should be able to find an output in the detector stage where a voltage changes proportional to received signal level.

 

[daisy8350z]

Ok thanks Mike. Will pull a radio apart and see what I can find.

Really I wanted to build my own circuit so I can incorporate it into a larger design.