I am still in the process of searching for and collecting components for measuring voltage, wave form and amperage. While that is going on I have also been engaged in searching for lighting equipment that will indicate when the electric fence wire is ‘live’.
After two days trawling the Internet some success has been achieved.
Firstly, electric fence manufacturers such as Gallagher, Patriot, et al do offer warning light accessories that clip onto a fence wire. Some seem to be powered by the pulses and others will only activate when there is no pulse present. Other kit contains battery power. Trying to find recognizable circuit layouts for this kit has been wishful thinking so far.
I then turned my attention to motor vehicles and in particular ignition wires for which there is testing kit. Most of this is associated with engine timing and I eventually found several circuits that looked promising.
The circuit components are fairly easy to acquire but the main difficulty is with the ‘pick-up’ which usually surrounds the ignition wire. Commercial timing guns feature a clamp which contains a U shaped ferrite with x number of turns of magnet wire. The opening aperture for the wire can be covered by a sliding ‘door’ which also contains a ferrite to make the thing box shaped. I can’t find any of these items locally so I decided to make my own.
Fortunately YouTube contains a video from someone who has been down this road already so please view the following URL:-
The chap also has a web site which contains more detail:-
http://www.howtoalmanac.com/kevin/projects/automotive/timinglight.htmTrying to find a suitable ferrite that can be cut up for the purpose proved impossible so I rummaged through my odds and sods coils box and dug out two pieces that seemed suitable for the job. Another coil was deprived of its fine wire winding and the first U ferrite contains many turns which were not counted at the time. The second ferrite – the E shaped one - contains 150 turns.
Along comes testing time and Machine A is set up as is the test circuit. Most things that I build always fail first time around so I was not imbued with great optimism. The ferrite was placed under the ‘fence wire’ and the machine turned on and lo and behold the test circuit red LED showed a small flash in tandem with the machine pulse. The red flash was difficult to see so I recalled the comment in the video where the speaker recommends a high brightness LED. Later in the day I made the changeover and the difference is spectacular. A nice bright white flash.
Human curiosity being what it is, I then moved the ferrite from under the ‘live wire’ to test the operating distance and found the following:-
9 inches (230mm) No perceptible signal to trigger LED
8 inches (200mm) to the wire itself An ever increasing signal with proportional LED brightness.
I then tested this in circle form using the ‘live wire’ as the centre and found that the test circuit would work anywhere around the ‘centre’. The non-working and working distances are shown for 9 inches and 8 inches above which are the radius of circles.
Car ignition leads Tested on a Mazda 323 which appears to have HT coils for each plug – ferrite adjacent to the wires with corresponding bright LED flashes. Maybe detecting adjacent ignition wires but it does work.
This was interesting and as far as I got in the afternoon. It therefore seems that the output of Machine B at X voltage and Y amps will send out a pulse that has an energy ring of approximately 16 inches (406 mm) in diameter around the wire itself. Perhaps readers can tell me more about this.
My next test will involve a long run of insulated wire including ‘connectors’ to represent ‘gateways’ that occur in fences to see if the same energy circle runs through the wire at a greater distance.
I mentioned earlier that I found other circuits during the search and here is another that I plan to build – follow the URL:-
http://www.sportdevices.com/rpm_readings/I have converted some of the circuits into Express PCB
Schematic files so they are available for easy and clear printing. If anybody wants them in soft format let me know when all have been tested and reported on.
Comments welcome.
David in HK