Small electricity problem to solve!

[dedeleco]

By any chance, I come across your Pb of this forum, and I come to put my grain of salt.
I have experience in various electronics and also in personal alarm.
I know the Pyroelectric Conrad telephone transmitter (the slightly more expensive one
http://www.conrad.fr/alarme_avec_transm ... 8759_52251
with remote control.
I use one as an alarm in a second home on a landline phone, as well as the inexpensive pyroelectric detectors of the trade good as an alarm by tinkering and we can use the presence detector without problem in different ways, either for a burglar or other animal , (but it is sensitive to the strong movements of leaves by wind which are in its field). Otherwise it does not trigger, except an animal like a lizard that walks on it (case experienced)!
We can connect to the pyroelectric electrical system but we can also move mechanically in front of a plate that triggers or Heat with relay an electrical resistance of a few degrees (10 ° C) a few seconds to a few cm, which triggers for sure, reliable method very simple because no connection to it, nor optocoupler, etc. !!.
Any thermal variation therefore infrared (human body 10 ° C a few m) triggers !!
The sensitivity is reduced by removing the white Fresnel lens at the front for infrared (rewindable).

I think I can help you, also tell me what you have already achieved because often in electronics the first idea can be simplified.
You were talking about GSM but it seems that you have a landline phone.
The fixed telephone and the GSM are not very connectable together.
You can use two cheap Conrad walky talkies if the distance does not exceed a few km, without subscription.
Now I seem to have seen that the mini portable subscription is 5 € per month (30min), useful, for alarm which I think about in my case with camera and sending email with the photo of the burglar !!
I have two cameras running like this on fixed ADSL for less than 100 €, TVIP110 from trendnet!
You can have the picture of the horse going !!

[Forhorse]

Good evening Forhorse.

You are faster than me: I have not yet had the time to do my editing with my alarm-transmitter.

I remain interested in your system if of course it is reliable: my fleets have 3 levels of wire; will your system detect 1 broken wire?

Keep me posted on the results of your tests.

As we said a few months ago, he could do it but it depends mainly on the way the fence is made. The fence must not be closed or the system will not work.
If you use 3 wire heights you can imagine connecting the current to the top wire; do a lap without looping, descend to the middle level, repeat a lap, still without looping, descend to the bottom wire, finish the last lap and connect the detector at the end, so the 3 wires are monitored.
but it may not be necessary either, monitoring the middle thread would be sufficient, in my opinion, when riding the fence, often the 3 threads clear. In any case mine do like this
So in this case you feed on one side, you go around without looping and at the other end you do not connect the 3 wires together and you connect the detector to the middle wire.

My system should be reliable. The high voltage part worked all night without worries, I think that under these conditions if it were to burn it would have done so quickly.
I just had a problem when I wanted to try on a slightly beefier fence, it worked but the resistance started to start between them.
The component values ​​are good but I have to spread the voltage over a larger number of resistors (there I have 2 in series, each resistance is eaten roughly 1700V, I have to put 5 or 6 so that they only have to support around 500V)
The first prototype should be operational by the end of April or the beginning of May.

[dedeleco]

Small note, the horse parks are often hundreds of meters tall and then all electronics must resist lightning falling in the vicinity (a few lightning strikes per km2 / year!) And even at a hundred meters we have a stroke of thousands of volts which destroys the electronics connected to wires even a few tens of meters.
In my house I put lots of varistors and lightning protection because I had destruction of the VMC motor and disjunction with lightning far away, but not my alarm of personal achievement super protected !!
Even the varistors do not protect because they let the voltage rise a little more and therefore we must think strongly about surge protection, (photocouplers, resistors, varistors and zener diodes, etc.) otherwise the electronics and relays even small motors are often redone every year

[Grelinette]

Hello everybody

I am glad that this subject is taking up a bit of activity because I ended up concluding that a simple solution was not possible. So I preferred to postpone this tinkering with the uncertain result.

To fully understand the problem, I summarize the application for those who have just arrived, in particular dedeleco which offers its help:
This involves putting a monitoring system on a fence with several levels of electric wires.
If the fence is broken (panicked horses breaking it, wild boars tearing it off, walkers opening the park, ... a system warns that there is a problem.

At the start, I started with the idea of ​​putting a GSM transmitter in order to secure a park far from any house, but it seems that this type of installation is too complex and / or too expensive.

That said, before developing the information transmission system, it is necessary to develop the fence control system.

Forhorse offers a system that tests the voltage return at the energizer level (correct me if I'm wrong).

For my part I thought of adding a simple electric wire which follows the fence and in which passes a low voltage current which keeps an open relay. If the fence is broken or opened, the relay triggers an audible alarm and / or a phone call.

[dedeleco]

Another remark, to detect high voltage, no need for resistance, but simply a rudimentary capacitive effect is enough by putting two metal sheets of a few cm2 face to face at a distance between mm and cm, and it works as a presence detector. high voltage, with a usual transistor (not more sensitive MOS but too fragile to overvoltages) and some resistances in the megaohm. If the high voltage is pulsed, these pulses can be detected with diodes and capacitance easily. The principle is that of the capacitive presence detectors sometimes used for keyboards.
It protects against lightning (better than the HV resistance), with resistance and zener diode (varistor too capacitive).
Even a house wire alarm dies with distant lightning without this type of protection, rarely but certain, over 33 years of personal experience!

Otherwise this site provides different GSM books and modules:
http://www.selectronic.fr/recherche_produit.asp
http://www.selectronic.fr/article.asp?a ... 10.1800-32
http://www.selectronic.fr/article.asp?a ... =10.5395-2
http://www.selectronic.fr/article.asp?a ... 10.9515-16
Probably the cheapest GSM call module with the inexpensive fixed telephone alarm.
http://www.conrad.fr/module_d_8217appel ... 655415_FAS
Without subscription for a few km
http://www.conrad.fr/set_d_emetteurs_re ... 895_779095
They are simple and therefore controllable by relays on the buttons very easily, very cheap, without subscription for a few km.
by taking a little more expensive, the range is more reliable.
http://www.conrad.fr/set_d_emetteurs_re ... 895_712026
http://www.conrad.fr/set_d_emetteurs_re ... 895_779089
We save the GSM subscription which is not given every year.

[zorglub]

some breeders use in mountain parks unsupervised and open to ublic (hikers) a system of baffles allowing the passage of a man on each side of the park
the electrification, when there is none is active on this passage
and apparently there are no problems ........

[Grelinette]

some breeders use in mountain parks unsupervised and open to ublic (hikers) a system of baffles allowing the passage of a man on each side of the park
the electrification, when there is none is active on this passage
and apparently there are no problems ........

This system is for cattle. In general at the level of the open passage there is a kind of grid which prevents the cows from passing but that does not stop the horses which can be seriously injured.

The problem for equines (sports) is that they are often parked close to urban centers with all the risks that this generates: opening of the park by walkers, thefts, accidents on the public highway, vandalism, ...

The problem is not to leave a passage for men (we easily pass between the electric fences) but to warn in the event of an open or broken fence problem.

[dedeleco]

Inexpensive video cameras on GSM (even with wifi 100 €) or fixed allow to monitor sending a signal (with adjustable threshold) with email each time something happens, burglar or horse or strong wind stirring trees (if in the field near the camera) in addition and also a photo at regular intervals from minute to hour or day !!
I have this on my secondary and main house as cheap surveillance with ADSL.
So I know the cause of the alarm for much less than a commercial alarm without a camera !!

[Grelinette]

Another remark, to detect high voltage, ... "

Your remarks are interesting but the final complete assembly remains to be found!
A high-voltage detector in a fence may be the solution, although it must be installed according to Forhorse's advice: a fence that does not loop, and that the detector is placed at the end of the fence. If the fence is broken just after the detector, it will not detect anything and yet the fence will be opened.

I remain skeptical about a system that tests for the presence of high voltage current. Firstly because the current passes by pulses and also because a partially broken fence or on the ground can continue to let pass the pulses.

[dedeleco]

The pulses are even easier to detect than static, because the simple capacities give an increasing alternating signal with the frequency to finish in radio frequency on km of distance between the two plates roughly !!!
A cut wire of high tension in general drags on the ground which often wet makes lose current towards the ground, and the high tension therefore decreases (current limited to mA? If not fatal with a capacity and a resistance in the range of megaOhm!).
So a simple assembly with a capacity of 1cm apart which detects a change in the high voltage of a few seconds (always the case with the electric discharge in an animal) will detect every time (and even the rare lightning strikes at hundreds of meters ( a few per km2 per year)) !! We can provide a sensitivity adjustment by potentiometer, because we can detect grass in the wind that brushes the wire !!!
It is necessary to know the characteristics of your high voltage, order of magnitude of frequency of the pulses, value of the voltage (1000V?) And peak current (mA) or the website selling your electric fence if it gives information.
Nothing prevents putting different systems in parallel voltage and detector wire.

Info a cheap Conrad electric fence power supply:
http://www.conrad.fr/mini_generateur_ha ... 212616_FAS
that I have for spreading wild boars, but ultimately that I did not ride (the hunters were effective) and that I can test!
We can detect the 12V current from the HV power supply because during a discharge it has a detectable current peak as easily.

This basic electronic system (principle of presence detector) will detect any change like animal, branch which falls on the HT wire and lightning far away and even at the maximum of adjustable sensitivity the approach of the wire by an animal without touching it (principle of the keyboard capacitive touch) !!!
With additional cameras during an alarm you can see and count the horses for cheap (the annual GSM subscription is the most expensive) !!