I'd like to switch on/off my electric fence remotly... I've tried wireless transmitters but the range is limited even when I got 1km capable devices.
I'd like to do it via the electric fence cable directly. Gallagher does have a product that does this but you need a specific model of charger (on of the most expensive ones) and the remote device, hundreds of $).
I just need help/advice how to send/recieve the signal down the electric fence which is being pulsed with 5-7kV. The relay on/off is simple.
Thanks for any help/advice
Hi, welcome to the forum.
Which wireless modules did you try, and what is the distance ?
The RadioHead RF_ASK mode is for wires, for wireless, for anything that needs to transmit data with a checksum and some fault tolerance. However, with 7KV pulses, even RadioHead might not work.
Could you transmit something in between the pulses ?
thanks for the reply... I've tried one of the 1000m (ideal) transmitters/recievers/relay with the more expensive transmitter... must swap out the 9v battery today and test again...
If its doable and I've seen from Electric fence company (http://gallagherelectricfencing.com/products/gallagher-remote-control) and there are quite a few patents (US6084505A - Method and apparatus for sending signals over an electric fence line - Google Patents) which I understand work by sending short duration high voltage 1-2kv each remote can put out with different time interval between each pulse to distinquish different remotes etc. It also says that they pulse 5 times, but if the base station recieves 3 out of the 5 then it is valid and operates the on/off (fence puts out max 7kv pulses). So I'm thinking they remote control dosn't even wait to send between the fence pulses, but could do.
I've though of a High voltage opto-coupler on the base station side, along with an arduino of course and a relay. And perhaps arduino with opto-coupler to detect the fence pulses and send remote message between them or 555 timer etc.
I lack the hardware experience to know what bits to put together, but with some advice I think I could put it together etc.
If you can send those pulses whenever you want, then you can send any information. But I don't know what is needed for that. You might have to alter the electronics of the high voltage pulse generator. That is dangerous, even with an optocoupler.
You don't need 555 timers anymore, the Arduino can be used for that.
What is the range in the field that you need ? There are long range XBee modules. They are reliable. On Ebay there are many claim for 1000m, but they might only be 100m with some luck.
My main problem is safety. I don't know how a relay could be used. Switching 7kV requires a special relay. Up to 1000V is not a big problem. Normal safety as used for the mains voltage is often good enough for 1000V. But at 7kV a spark could find a way via dirt and moisture, or could spark towards a case, or cable shielding, it can turn plastic into conductive coal-like-material, and so on.
Hi, are these energisers battery powered (12V)? If so, then it should be easy and safe to switch them on & off by switching the 12V supply on/off with a relay or power FET.
Did you see these?
I would steer clear of mixing data with high voltage spikes!
Thanks for the links...
The RF solutions always report ideal, although its an open space, we need max 1km from base, but I think they often can't do that.So if it can be simpler through fence wire I'd like to explore that possibility.
I was going to only switch on/off the 240vac supply to the main fence charger, so pretty safe and simple with simple relay on that.
The High voltage max 7kv has an interval between pulses of 1s so I was planning, based on looking at the patents to just send the max five short High voltage pulses 2kv (which are needed I understand to get through fence back to main sensor via possible obstructions and less than ideal connections.
those five pulses have to be listened for and have a particular interval to be registered as valid, and the patent mentions that perhaps only 3 have to be received to register as valid and switch on/off fence. I guess that would account for being interrupted by the main charger pulses.
So what I wanted to understand was
- How to generate those 2kV pulses from a 9v battery
- How to sense the 2kV pulses, perhaps using an opto-coupler (rated for max 10KV), which I thought was quite simple, just a different kind of version that can handle and isolate the high voltage.
1 ) A normal 9V battery can create pulses of 2kV, but not 2kV for a fence. It is not something you can build yourself by soldering a few components. I have doubts about safety with 2kV, and also about connecting the 7kV circuit with the 2kV circuit, even if they are not active at the same time.
The Arduino is a 5V or 3.3V microcontroller. Using optocouplers, transistors, mosfets and relays up to about 60V is no problem. For a circuit that is connected to the mains voltage, that requires someone who knows what to do and what not to do. A reliable 7kV/2kV circuit is something even more advanced.
2 ) I don't know how to filter 7kV or 2kV pulses from a fence to be read with an Arduino Perhaps just a voltage divider with resistors and a filter and clamping diodes. An opto-coupler requires current within certain limits.