14 yo girl electrocuted trying to charge mobile in bath

[JohnW2]

The fax ECM octets aren't individual bytes, but octets of multiple collected fields of data. It's been years since I looked at the full protocol, so I'm afraid I can't recall the details off the top of my head, but each checksum covers a large enough amount of data to be quite a reliable method.

Fair enough. As I said, if a checksum is calculated across a large enough number of elements, the probability of an 'erroneously correct' checksum can become vanishingly small.

As you go on to say, a single parity bit is the crudest error-checking method of all, since the 'check bit' can only take one of two values (hence can only detect odd numbers of errors). In general, the more unique values the 'checksum' or whatever can take, the more reliable will it become.

Kind Regards, John

 

[securespark]

with decent size buttons

I find these on my Mega 6.3" do the trick for me!

You need to borrow a teenager from somewhere to help you out.

Last time I did that, I ended up in the nick!

 

[securespark]

As far as I understand from my conversations with the likes of Paul Cook at the IEE (as it was then), the regs guys in the UK were anti socket in the bathroom when other countries were for them. They were deleted from the 13th.

As I understand things, Wylex developed their RCD and put it on the market in 1974 but I don't know if that was the first or not? So earlier sockets in bathrooms round the world would not have been RCD protected.

When the regs were updated to the 17th, there was great pressure to bring many of the regs in line with European practice and allowing sockets in bathrooms was one of the concessions that was made, albeit on the proviso it was 3m from the tub.

 

[PBC_1966]

As I understand things, Wylex developed their RCD and put it on the market in 1974 but I don't know if that was the first or not? So earlier sockets in bathrooms round the world would not have been RCD protected.

What are you counting as being within the scope of the modern RCD term? Current-operated ELCB's had been around for years by then, although they generally had trip currents of 500mA or more.

But if you're talking about more sensitive devices, the American GFCI (nominal 5mA trip) became available in the late 1960's, and the National Electrical Code first started requiring it for certain locations from 1971 onward. Bathroom receptacles came under the NEC's GFCI requirement in 1975 (although with some states not adopting new editions for several years, it was probably not until the late 1970's or early 1980's that all new homes nationwide needed it to be in compliance with the relevant building codes).

 

[ericmark]

Oh a blast from the past. The fax machine was a 19th century invention came out before Morse code was invented and was invented by a Scotsman, but developed by an Italian, and first commercial one was in France it stood ten foot high and weighed 5 ton and one it seems is still in a museum in Paris. It has been given many names, in USA they referred to wiring a picture, and radio hams called it slow scan TV. It was very big in USA until the TV was invented. It had a revival when it was realised it could show Japanese characters and when I was in Hong Kong everyone had fax and the phone ringing tone changed between fax and telephone so telephone did not ring when a fax came in.

The telex machine however unlike fax was installed by the post office so the output was a legal document it was too easy to fiddle the fax so you thought it came from one person but in fact came from some one else. Also a big problem buying paper which got used up with all the adverts being faxes to random machines. However telex was expensive.

Both fax and telex were immediate however some one needed to see it had arrived so often followed by a phone call. Speeds were slow common was the 1400 baud rate. I still have one machine that will send a fax but not receive the printer part has failed. I think first bit of transmission worked out baud rate mine could send at 2800. Had some firms where I needed to fax time sheets. But in the main email has replaced it.

First email I used was called packet radio and as to speed talking UK to Australia it was a case of "Hello Joe" then make a cup of tea waiting for the answer. But first email I used was one to one the BBS only held the message long enough to re-transmit it. Some time we used digipeters which were truly live talking. However with email today and I suppose a small message service is only a short email there can be a delay.

The telecommunicator can't really any longer call is a telephone as that only refers to speak. So well could have a smart-tele or a tele-smart but not really a smart-phone as phone refers to speak only. Same as could not really call one number for telephone and fax telefax that just means fax at a distance it would be called fax/phone.

I had to upgrade for my father-in-law and mother the mobile computer I now carry around has a program or application which allows me to locate father-in-law and to view my mothers living room. If it was not for looking after the old folk I would still have a simple phone. However both young and old do silly things, my mother saw the red neon on an extension lead and thought it was on fire so put it in a bucket of water. Lucky no one injured, now arranging for a re-wire and RCD protection.

She has answered the phone using the remote assess door bell and tried to answer door using the phone, to be fair they do look similar. She has a very simple mobile phone large keys with just numbers on them, and one big red button which if pressed sends me a text message "Help this is mum." at which I turn on camera and can listen and talk using that although not at the same time.

Things have move on even my android looks nothing like the original

however not as paranoid as Marvin was. But I don't use it in the bath room if the phone rings while I am in the bath, then I will look at caller ID after I get out. But most have no ID and that's simple if they will not say who they are I don't want to talk to them.

 

[bernardgreen]

The first fax machine I saw was about 2 foot square and about 4 foot tall. Solid metal cabinet. Used a rotating drum with photo paper on it. All transmissions were pre-arranged as the paper had to be loaded just before the connection was made. The call had to be booked and set up via the operator to ensure it was a low noise line. After reception the drum had to taken to the dark room and the photo developed. Then came the interesting bit. Not all machines used the same size drum so the ratio of horizontal ( round the drum ) measurement to vertical ( along the drum ) would not be the same on the received image as it was on the transmitted so the photographic process had to adjust the ratio. ( I was never told how this was done ).

This first meeting with that machine was a service call for the machine ( the company I worked for then would service almost anything electrical or electronic ). The news agency in London were expecting a photo of some model wearing a dress from a Paris exhibiton and their fax machine wasn't working. The international low noise fax line that was connected was costing money.

The fault was fortunately an easy one to find. A burnt out heater in the double diode valve that rectified the HT supply. Yes it was all valves. The repair was simple. Smash the glass, remove the innards and fit two semiconductor diodes and two resistors to the pins in the base of the valve.

Within seconds of the machine having powered up ( amid relief that had I got it working ) an urgent sounding voice came out of the loud. "Ici Paris, are you ready ?"

And I never did see that picture that all that fuss and expense was about.

 

[stillp]

No, standard telex.

Definitely no per-character handshaking there, even when transmission was over RF carrier systems.

Oh well, perhaps my BT trainer was wrong then. I'm sure you'll forgive me if I continue to believe him though, rather than some unknown guy on a forum.

 

[JohnW2]

Oh well, perhaps my BT trainer was wrong then. I'm sure you'll forgive me if I continue to believe him though, rather than some unknown guy on a forum.

Are you sure that you an Paul are not talking about different generations of telex? As Paul says, AFAIAA, with original/traditional telex, once a connection was established, there was simply a direct 'wired' connection between electromagnetic devices at both ends, thereby not really offering any opportunity for 'handshaking' in the normal sense. When 'electromagnetic devices' gave way to electronics, the possibilities obviously increased.

Kind Regards, John

 

[securespark]

Have I got the wrong thread?

I think so

Kind Regards, John

Shame on you EFLI! I've never done such a thing!

 

[stillp]

Are you sure that you an Paul are not talking about different generations of telex?

Maybe. My training was in the late 80s/early nineties, but I was sure I'd been told about handshaking in the early eighties.

 

[JohnW2]

Maybe. My training was in the late 80s/early nineties, but I was sure I'd been told about handshaking in the early eighties.

Yes, but even 'early 80s' was decades after traditional telex appeared, and probably plenty late enough for electronics to have become involved to a significant extent!

Kind Regards, John

 

[stillp]

Yes. I don't know what era PBC is talking about, but there was plenty of electronics in our telexes. Are you sure though that you're not confusing telexes with teleprinters?

 

[JohnW2]

Yes. I don't know what era PBC is talking about, but there was plenty of electronics in our telexes. Are you sure though that you're not confusing telexes with teleprinters?

AFAIAA, there's not really a material distinction (at least, not in the early days), in that 'traditional' telex machines essentially used teleprinter hardware. Again AFAIAA, the 'Telex' system was introduced as a network (with exchanges etc.) essentially for connecting teleprinters to one another. I'm sure Paul will correct me if I'm wrong!

Kind Regards, John

 

[bernardgreen]

once a connection was established, there was simply a direct 'wired' connection between electromagnetic devices at both ends, thereby not really offering any opportunity for 'handshaking' in the normal sense.

Telex used +80 and - 80 volts in the loop +80 as a space and -80 as mark ( IIRC) and a Carpentor polarised relay was used to regenerate the signal at the receiving end to drive the punch solenoids

Telex connections... If the connection was direct machine to machine then the transmitting station could monitor the current in the loop to verify that the connection was still good but there was no handshake on standard telex equipment. This did not work when the circuit went through a repeater / regenerator at the telex exchange(s) along the routing of the connection.

There were devices which could be added into the loop to create a check sum on the data received which could then be sent manually back to the transmitter as a "message". The operator there checked if it matched his check sum and if it did he sent a confirmation message. As I recalll these were not approved by the GPO

 

[JohnW2]

Telex used +80 and - 80 volts in the loop +80 as a space and -80 as mark ( IIRC) and a Carpentor polarised relay was used to regenerate the signal at the receiving end to drive the punch solenoids

Indeed, but that was true of teleprinters in general, not just telex. I spent a good many hours during my "mis-spent youth" playing with teleprinters (mainly Creed 7Bs)!

There were devices which could be added into the loop to create a check sum on the data received which could then be sent manually back to the transmitter as a "message". The operator there checked if it matched his check sum and if it did he sent a confirmation message.

If that was done in the original 'electromechanical' days, how on earth was the checksum calculated - it sounds as if a 'Babbage machine" would have been needed!

Kind Regards, John