the fenz-tika
very quickly ...
The fenz-tika is a device for checking that a powered-up electric fence is operating as it should. It costs less than an electric fence voltmeter, is more robust, and does not use a battery of any description. For fault-finding on a big or complex fence system, there is no substitute for an electric fence voltmeter.
construction and basic use
This is the whole fenz-tika (fence ticker in English) resting on a standard house brick to give an indication of size. If house bricks are a different size where you come from, the main body of the fenz-tika is 185mm or seven and a quarter inches long, and 38mm wide. This fits into a normal pocket on a working pair of trousers. A 5mm outside diameter clear PVC tube plugs securely into the top housing of the fenz-tika, and this terminates in an earpiece, which you just hold against your ear while resting the 'business end' (marked with red tape) against your electric fence, with the fence power turned on. If you can easily hear a regular ticking through the earpiece (assuming your hearing is OK) the fence is working and not being shorted to ground. The fenz-tika generates the click you hear through the earpiece from the high-voltage pulse passing through the fence. It needs no battery, and most of the body of the instrument is solid 12mm thick high density polythene, with a central machined cavity holding the circuit. The red-marked end has an aluminium skin for contacting the fence. The fence pulse passes by capacitance through 2mm of epoxy-fibreglass insulation, then is transformed down by the internal circuit to low-voltage that makes a small piezoelectric speaker click. The click is passed up the PVC tube to the earpiece. The circuit has no ground line, but relies on the capacitance to ground of the human body, so you have to be grasping the 'hold this end' label to make it go. The current required to make the click is so small, the human body feels nothing. If an unsealed fence-tika is used in the pouring rain, and gets internally soaked, yes you will get the normal electric fence shock as the 'business end' contacts the fence, and you may damage the internal circuit. There is no need to understand the technical details in this description - they are provided only for those who want them.Accidentally (or deliberately) picking up the fenz-tika by the red 'business end' and applying the 'handle' to a working electric fence will do no damage to you or the fenz-tika, since it is double insulated. The circuit will even function, but the clicks will not be as loud as usual. This reverse operation can be used on purpose where you want an insulated tip only close to high-voltage wires, so it cannot short anything out or together. Any clicks you hear are from capacitive coupling to the voltage sensor, so there is no direct electrical contact.
holding the fenz-tika against the fence
A few words on not killing yourself. It is assumed you are testing your own electric fence, and not one you have happened upon. Electric fence energiser units are made to get maximum unpleasant shock from a minimum of power input, and to keep the shock delivered to the target to a safe level. Only criminals, or perhaps the military, would wire up say the AC mains to a fence, or even specifically generate a high DC voltage for that use. Neither will damage the fenz-tika, but it will not click to indicate danger, and contact with such a fence wire could easily kill. Safely detecting mains-level AC and DC voltages is best done by a good quality mains testing neon screwdriver, operated according to the manufacturer's instructions. A commercial-grade neon spark plug tester, from a professional automotive supplier, may be used to indicate high voltage AC and DC. We have done no practical work in this area - much too dangerous. If you want to detect any voltage that might be applied to any fence, you have a lot of skilled and tricky work to do, and we are not getting involved. If I were James Bond, and encountered a non-ticking fence that I still suspected, I would short it to ground, which would look after my immediate safety at the expense of blowing any fuse connected to it. All the alarms then sound, followed by close-ups of big slavering dogs.
dirt, dust and water
The fenz-tika needs no battery, and will probably only be used very rarely, unless you have a fence that frequently gives trouble. Workshops being what they are, it is likely to be chucked on a bench and left until it is next needed. Unless you are angle-grinding nearby, the fenz-tika is not likely to build up a thick enough coating of grime to make the insulating surface conductive when dry. If the fenz-tika surface is wet or damp a light coating of dirt is enough to make it conductive. Insulators have to be kept clean, or cleaned before use, and so does the fenz-tika. It is much less trouble to store it properly out of the dirt, but before we look at that let us assume it will be neglected and well covered with grime when next needed.The weak point of the fenz-tika case as regards dirt and contamination is the hole where the PVC earpiece tube plugs in. Much less space is needed for storage if the tube is removed, but that allows airborne rubbish to settle into the hole, and if it is two years before the fence fails, enough may have landed down there to stop the piezo speaker working. If you must leave it out on the bench, do it either with the tube still in, or keep it upside-down - that is resting on the four plastic screw heads. Dust and dirt fall downwards, and with the tube hole on the underside it will stay clean. Another way to keep dust and water out, which also applies if the fenz-tika will be spending days in your trouser pocket, is to stick a short strip of insulation tape over the hole, or push a small rolled ball of 'blu-tak' (TM) over and into the hole. When you need to insert the PVC tube, just shift the tape off the hole, sticking it to the body of the fenz-tika until you need it again. The only problem with the tape is sticking it on when there is water down the tube hole already. The speaker then stays damp for months if the fenz-tika is a sealed unit, and is most unlikely to work again. We can service fenz-tikas, replace speakers etc, by the way, if you post them back to us, hopefully in the original tube.
To clean a really dusty fenz-tika make sure before you start that it is dry, by bringing it indoors for a few days. Turn it upside-down and tap the four screw-heads repeatedly on the table. If the dust in the tube hole is dry, enough may fall out to allow the piezo speaker to function. After this put a short length of tape over the tube hole, and brush or flap with a dry rag to get the rest of the case clean. Sealed or unsealed fenz-tikas (see later) may be wiped with a damp rag, but only the sealed variety can handle anything wetter.
clean storage
The fenz-tika is posted or supplied in a cardboard mailing-tube with two plastic push-in ends. The tube makes a pefect home for the fenz-tika when not in use, and it will stay clean in there. If folding up and squeezing in the earpiece tube is too fiddly, rubberband it to the outside of the mailing-tube where it will not get lost. Wipe or shake the dust off the earpiece tube before you plug it in. Most of us carry handkerchiefs. A cardboard tube is permeable to water vapour, making it an ideal dust-free container where a damp fenz-tika can dry out, assuming you can provide warm dry conditions.Industrial sealants and adhesives come in polythene disposable canisters that fit into applicator guns, and I assume like bottle tops, the size of the canisters is a World standard. Silicon rubber gutter sealant is particularly easy to clean out of an empty canister. You need one canister with the nozzle end cut off, and two internal pistons which are used to drive out the sealant. Smooth the ends of the canister making a perfect tube. Push-fit one piston the 'wrong way round' into the difficult end of the tube, where it will make a cap. The fenz-tika minus tube is the exact size to push inside this plastic transit case, and the second piston is pushed in the 'right way round' to keep the fenz-tika inside. By the way, ugly self-adhesive labels on the canister from its sealant days can be removed before surgery starts by filling the canister with hot water. That warms the label adhesive, making it soft enough for the label to be easily peeled-off.
rainy days, and what they cost
You do not see many electricity power crews working on overhead lines when the weather is wet. Working dry is much safer. All you are risking with an electric fence is yet another 'bite'. Most electric fences lose power by leakage in the wet, but to compensate, wet cattle are much easier to shock. If your fence fails totally each time it rains, and you cannot duplicate the effect with a dry day and a watering-can (I suggest a plastic one) you may be out in the rain testing your fence. The standard fenz-tika is not designed for this. It is reasonably cheap (60 Australian dollars plus post), but if used in the rain, water can leak into the seam between the circuit board and the main body and bypass the insulation. You may get a 'bite' from your fence, and high-voltage may reach the internal circuit and destroy components. The 'good' news is the standard fenz-tika comes apart very easily for component replacement.The sealed fenz-tika is mechanically and electrically identical to the normal version, but costs 80 Australian dollars plus post. The top cap is sealed to the circuit board, and the circuit board underside is sealed to the main body. We use a soft sealant that does not set. First this sticks well to high density polythene, and second it makes dismantling fairly easy. Once the sealant has been applied, the four plastic holding screws are inserted and tightened. Care is taken that no sealant makes its way into the piezo speaker. If are a sealant expert and want to save yourself 20 dollars, you can seal the fenz-tika yourself, but if you have done so, honouring implied warranties is at our discretion. If we can't get the thing apart for service as a result, or have to replace the circuit board, you pay.
With surplus sealant cleaned off the outside, and the normal tapes applied to the ends, the sealed fenz-tika is ready for use. If it really is wet outside, it is well worth giving the fenz-tika a light coat of wax (silicone car polish or similar). Be sure when you do this to first put a short strip of tape over the earpiece tube hole, or plug in the tube, to stop wax polish getting down the hole. Most rain water that hits a clean waxed surface just falls off, and the rest forms isolated beads that will not conduct high voltage. Before you go outside, push the earpiece tube right in to the hole, and keep it there until you get back in the dry, and you have wiped off the fenz-tika. We don't suggest use against underwater electric fences (more James Bond?) but a sealed fenz-tika should keep out falling rain for a pretty long day. Note the earpiece tube is open all the way down to the piezo speaker. Getting water down that length of small tube is close to impossible, but you have been warned. We can't write a manual on fault-finding wet electric fences (unless you write in and tell us you need one), and assume if you are out there in the wet successfully avoiding personal shocks, you know what you're doing. When you come back to the warm and dry, bring the fenz-tika with you. Let it warm up, then remove the tube after wiping the outside of the case. Give it a few hours to dry out.
dismantling
This should be the place for the normal grim warnings about even daring to think about disturbing the innards of a manufactured product. It isn't. Many people with the common-sense to buy a fenz-tika can also be trusted to take it apart, and there may be an urgent need to get it going again. The only specialised component inside is the small piezo speaker, and a surplus professional electronic component trader is the best place to look. Any electronics serviceman or enthusiast should be able to decode the circuit.There are three tapes holding down the ends and performing assorted other duties. If you remove them with care, they can be hung up by one end, and put back. Otherwise you will need 48mm metal aluminium tape, and 48mm polythene tape of the thick variety used for holding together the sheets that cover plastic greenhouses. A label printer would be handy. The red band is top-quality Nitto insulation tape. Remove the tapes.
For both sealed and unsealed units, unscrew the four hex-head plastic screws. The unsealed units just come apart into top, bottom and circuit board. There are no internal traps for unauthorised case-openers, and there is no wiring. Dismantling a soft-sealed unit requires care, and if you don't know what sort of care, don't do it. If the unit clicks on a fence when you put it back together, congratulations. Don't overtighten the plastic screws, which take a lot less force than steel or brass. If you have a non-working mess when it goes back together, send it to us (sigh ...).
current contact details
writer: Breck Bowlesdesign and manufacture: Breck Bowles Development
address: 7 Sykes Court, Pakenham, Vic 3810, Australia
phone and fax international: +613 5941 4789
phone and fax local: 03 5941 4789
please do not phone or fax overnight East Australian Time (as we sleep then)
e-mail breck@permaflate.com