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Author Topic: Lightning struck  (Read 7085 times)

NewtronStar

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Re: Lightning struck
« Reply #15 on: November 20, 2015, 11:37:14 PM »

I use lightningmaps.org all the time but I'm thinking of getting an alarm with an audible warning.

Yes you can build your own TS alarm

http://www.techlib.com/electronics/lightningnew.htm
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Weaver

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Re: Lightning struck
« Reply #16 on: November 21, 2015, 12:14:01 AM »

Some alarm gizmo like the following::
    http://www.skyview.co.uk/acatalog/SkyScan_P5.html
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Weaver

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Re: Lightning struck
« Reply #17 on: November 21, 2015, 03:33:11 AM »

My wife has bought the SkyScan P5 unit (URL given earlier).

I am too full of drugs (pain) to get into the lightning project now. Try doing some serious programming after four to six pints of your favourite ale and see how you get on, then stay like this for the next four years or so. I can get out of bed, and can make it as far as the bathroom, luckily, but that's about it.

I would need to find the fibre media converters that are fast and clean. And most vexing of all, I would need to source a pair of very short fibre patch links, a subject that is new to me. Not being optronics-literal is embarrassing.

And I need to acquire the VLAN switch and do the config, which is all made easy as there is an article on the Firebrick website or on the Andrews & Arnold support wiki or somewhere I forget.

But I would need to find a volunteer with a brain and with hands to do all the dog work. Basically, success means (i) getting a break in an Ethernet cable through the fibre-media-converter pair, and then (ii) getting a load of Ethernet cables into a VLAN switch and getting their outputs MUXed into one single output cable all tagged with the appropriate VLAN tag values 100, 101 etc (as used in the example VLAN config for switch to go into a Firebrick).

I might have someone in mind as a volunteer but I would have to buy her a lot of beers.

 
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benji09

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Re: Lightning struck
« Reply #18 on: November 21, 2015, 09:55:53 PM »

  Weaver, you are correct that the `PME' mains supply does not require an earth spike - unfortunately !   So in the event of a lightning strike at or near your electricity distribution substation, or pole, would likely cause your earth voltage to rise at your home.   
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WWWombat

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Re: Lightning struck
« Reply #19 on: November 23, 2015, 03:22:42 PM »

I would need to find the fibre media converters that are fast and clean. And most vexing of all, I would need to source a pair of very short fibre patch links, a subject that is new to me. Not being optronics-literal is embarrassing.

I was like this too, and decided to find out a little about it fairly recently. It turns out to be not that hard, really, but it has its own world of jargon.
Even getting the fibre itself should not be vexing.

Think of this through the eyes of "proper" enterprise networking, about 15 years ago. At this time, copper Cat5e was 10/100Mbps, and gigabit was left to optical. Perhaps as uplinks from an enterprise switch into the core business network.

Such switches could often be bought with a modular uplink slot, for a "GBIC" module. The transmission module could be bought separately, and determined what kind of uplink media was used, and what connector style. Generally, multi-mode fibre is cheaper, and for shortish distance (up to 500m), which single-mode fibre is for long distance, up to tens of km.

Subsequently, gigabit copper came about, and there are GBIC modules that support this, with RJ45 connectors.

Buzzwords: 1000base-SX is the standard for short-haul gigabit over multimode fibre; 1000base-LX is the standard for gigabit over single-mode. 1000base-T is for twisted-pair copper.

Example switch images: Cisco 3550 https://goo.gl/ke9Mdv
Example GBIC modules: Cisco GBIC modules http://goo.gl/ovJdzf

For those fibre GBIC modules, the standard cable would be a pair of fibre (one up, one down), using connectors known as SC (standard), and a fibre joint type known as PC (fibre cut at 90 degrees, and polished, compared with an oblique cut).

As time has gone by, multimode fibre production techniques have improved, and can be used for longer distances. The quality tends to be denoted in terms like OM1, OM2, OME (where OM3 > OM2).

Example fibre patch cable: Maplin has a 1m long, SC connector, OM3 cable for £3.59: http://goo.gl/AbRJzn
They have longer lengths too, and the lesser quality types.

As time has gone on, the modules have been made smaller, as have the connectors.

More recently, the transceiver module takes a form known as SFP, which is about half the size.
Example switch: Cisco 3560: https://goo.gl/HmjUxO
Example SFP modules: Cisco 100base modules: http://goo.gl/LU6NY3
Example SFP modules: Cisco 1000base modules: http://goo.gl/O9gaIP

In SFP modules, the connector may well be an LC style
Example fibre patch cable: Maplin has a 1m long, LC connector, OM2 cable for £3.69: http://goo.gl/nFR6f1

HOWEVER ...
Note that some of the media converters I pointed at before were for 100base-FX. These can operate as above (with dual-fibre cables), but can also use a single fibre for both transmit and receiver (2 different frequencies); it can use the same patch cables as above, but only using one fibre of the pair. This type of converter need to be bought as a pair, with opposing transmit/receive wavelengths.

Bringing all that back to your needs, all you probably need to do is:
- Choose your fibre type (eg multimode) and protocol type (eg 100base-FX, or 1000base-SX)
- Choose the copper type (eg 1000base-T, or "just" 100base-TX, to match your other hardware)
- Determine whether the converter has built-in optics, or needs a module adding (such as an SFP module)
- Determine the connector type (eg SC, or LC, or possibly ST) and the style of cut (eg PC) for the optical transceiver.
- Choose the appropriate converter & cable

For example, this kind of media converter needs an SFP module: http://www.tp-link.com/en/products/details/cat-4792_MC220L.html
Meanwhile, this kind has built-in optics, ready for SC-connector multimode fibre: http://www.tp-link.com/en/products/details/cat-4792_MC200CM.html

Both of those seem to offer only 1000base-T gigabit copper, not 10/100 fast ethernet.

This media converter is one half of a 100base-FX pair, using a single fibre with an SC connector: http://www.tp-link.com/en/products/details/cat-4792_MC112CS.html
The other half is a slightly different model number.

This media converter also uses 100base-FX, but with dual fibres: http://www.tp-link.com/en/products/details/cat-4792_MC100CM.html
Two of the same converter model can be used as a pair here.

What was once high-end enterprise hardware costing £thousands is now low-end, accessible hardware.

Hopefully that gives something of a flavour.

Edit: Looking at prices of the TP-Link examples I've posted here, I suspect that a pair of the MC100CM modules would fit the bill for you - provided you only need to connect to 10/100 copper. I haven't gone looking at other brands, though ... I deliberately stuck to one brand here so you could see a range of options.
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Weaver

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Re: Lightning struck
« Reply #20 on: November 23, 2015, 04:30:54 PM »

Thank you to WWombat for your thoughtful and generous reply.
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Weaver

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Re: Lightning struck
« Reply #21 on: December 22, 2015, 08:04:28 PM »

Btw the lightning warning unit
    http://www.skyview.co.uk/acatalog/SkyScan_P5.html
Has one really, really annoying design defect. Even on mains, it keeps going to sleep as if it were on batteries. Grrr. It won't stay on all night, and it's never on when you need it to be. >:(
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burakkucat

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Re: Lightning struck
« Reply #22 on: December 22, 2015, 08:53:36 PM »

Reading the user manual, I see --

Quote
2.) OPTIONAL EXTERNAL A/C POWER ADAPTER
Your SkyScan can also be powered by attaching the Optional External Power
Adapter. Insert the plug into the Jack located on the right side of the SkyScan.
The External Power Adapter can also be used with batteries installed in the unit.

When using the SkyScan with an External Power Adapter, press the Battery
Save switch twice to deactivate the automatic turn-off feature. The automatic
turn-off function is reactivated by turning off the Power On/Off switch.

IMPORTANT! Use of an External Power Adapter other than that supplied by
SkyScan will damage the unit or result in a loss of sensitivity and performance.
See the list of Optional Accessories (at the end of this manual). Many adapters
available through normal retail outlets produce high levels of noise which can
produce false triggering of your SkyScan.

The second paragraph of that section implies that it is possible to deactivate the "automatic turn-off function" but it will need to be done for every occurrence of a switch off / switch on cycle.  :-X
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Weaver

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Re: Lightning struck
« Reply #23 on: December 22, 2015, 09:41:13 PM »

That is definitely worth a "Doh!"   :-[

Many thanks indeed!
New brain pls.
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burakkucat

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Re: Lightning struck
« Reply #24 on: December 22, 2015, 10:39:51 PM »

New brain pls.

I don't think that will be necessary! (I had to read that section a number of times before I fully understood it.) Overall, it is not one of the better written manuals.  ::)
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Weaver

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Re: Lightning struck
« Reply #25 on: December 23, 2015, 04:57:30 AM »

Looking good so far anyway, following Burakkucat's tip.
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burakkucat

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Re: Lightning struck
« Reply #26 on: December 23, 2015, 04:30:17 PM »

Purrfect.  :)
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Weaver

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Re: Lightning struck
« Reply #27 on: January 05, 2016, 11:19:46 PM »

A few false positives. Three crying wolf instances today, sometimes hing in the house because the alarm fires sometimes when my wife moves around downstairs. Warning unit is upstairs in a bay window.
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