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Default Electrical question

I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?
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On Tuesday, 2 January 2018 23:10:04 UTC, wrote:
I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?


won't be a problem. But any mains fuse below 3A does fail in time.


NT
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On Wednesday, 3 January 2018 01:38:39 UTC, Bill Wright wrote:
On 03/01/2018 00:46, tabbypurr wrote:

But any mains fuse below 3A does fail in time.


Not when the load is constant and small. I fitted 2A or 3A fuses at
every one of the thousands of TV distribution head-ends and repeaters I
built between 1975 and 2015 and there was no problem with spurious fuse
breaks.

Bill


I fitted many 2A fuse years ago with tiny loads and many eventually failed. But not thousands. Perhaps they weren't as good quality as they appeared.


NT
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On Tuesday, 2 January 2018 23:10:04 UTC, wrote:
I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?


Your door bell system with transformer uses a lot of energy.
Low power but on all the time.
Consider getting a (wireless) battery replacement.
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On Wednesday, 3 January 2018 07:17:10 UTC, harry wrote:
On Tuesday, 2 January 2018 23:10:04 UTC, wrote:
I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?


Your door bell system with transformer uses a lot of energy.


nonsense

Low power but on all the time.
Consider getting a (wireless) battery replacement.


unwise
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On 02/01/2018 23:10, wrote:
I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?


Nothing wrong with it in principle. A 3A fuse would probably be more
useful.

You could also look at 2A plugs/sockets if you can't find a
PSU/transformer that can be wired directly. e.g:

https://www.tlc-direct.co.uk/Products/CB7046.html

Having said that, you can get neat bell transformers that can be wired
directly. What is it to power? Do you need DC or is AC ok?

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/


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In article ,
harry wrote:
Your door bell system with transformer uses a lot of energy.
Low power but on all the time.


And you think battery costs will be less?

Consider getting a (wireless) battery replacement.


Which ain't going to last 80 years. ;-)

--
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Dave Plowman London SW
To e-mail, change noise into sound.


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On 03/01/2018 09:59, Brian Gaff wrote:
Have you tested said wart does the job adequately? I've no idea of the load
but if its got any inductance in it then they don't like that very much.
Brian


It's fine with a big capacitor across the output.
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On Wednesday, 3 January 2018 10:37:47 UTC, Harry Bloomfield wrote:
tabbypurr expressed precisely :
On Tuesday, 2 January 2018 23:10:04 UTC, wrote:


I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?


won't be a problem. But any mains fuse below 3A does fail in time.


NT


Fuses range in value from ratings of 1,000's of amps, down to just a
few milliamps in equipment fuses. They only tend to blow when subjected
to either a fault load or a regular surge load.


by definition they don't 'blow' when they break, they just break.
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On Wednesday, 3 January 2018 12:18:19 UTC, wrote:
On 03/01/2018 09:59, Brian Gaff wrote:
Have you tested said wart does the job adequately? I've no idea of the load
but if its got any inductance in it then they don't like that very much.
Brian


It's fine with a big capacitor across the output.


yes, done that before. A switched mode wart would get rid of the wasted 2 watts.


NT
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On 03/01/2018 08:35, John Rumm wrote:
On 02/01/2018 23:10, wrote:
I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?


Nothing wrong with it in principle. A 3A fuse would probably be more
useful.

You could also look at 2A plugs/sockets if you can't find a
PSU/transformer that can be wired directly. e.g:

https://www.tlc-direct.co.uk/Products/CB7046.html

Having said that, you can get neat bell transformers that can be wired
directly. What is it to power? Do you need DC or is AC ok?


It's for a servant call board, almost identical to this:
https://www.youtube.com/watch?v=VNZxBMfUmZ8. There's also a repeater
bell at the far end of the house.

It was running, very feebly, on AC. I experimented with a bench supply
and found that it's much happier with about 5V DC so found a 5V wart in
a box and added a 470uF cap inside the indicator box. The socket needs
to be 13A because of the wart plug.
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On Wednesday, 3 January 2018 11:17:35 UTC, Dave Plowman (News) wrote:
In article ,
harry wrote:
Your door bell system with transformer uses a lot of energy.
Low power but on all the time.


And you think battery costs will be less?

The battery is only in use for a few seconds each week.
The transformer is continually drawing current


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In article ,
"Brian Gaff" writes:
I'm always finding fuses of many sizes in plugs stopping working recently
after about 10 years. the all just fell to bits in that the wire inside came
off the end.


I do see some old fuses at repair events which are not labelled
as BS1362. I have one which failed to interrupt the supply when
it blew and turned into an arc lamp inside the plug. There was
no evidence it was sand filled, so failing to break the circuit
is not unexpected.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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On Wednesday, 3 January 2018 12:30:33 UTC, wrote:
On 03/01/2018 08:35, John Rumm wrote:
On 02/01/2018 23:10, wrote:


I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?


Nothing wrong with it in principle. A 3A fuse would probably be more
useful.

You could also look at 2A plugs/sockets if you can't find a
PSU/transformer that can be wired directly. e.g:

https://www.tlc-direct.co.uk/Products/CB7046.html

Having said that, you can get neat bell transformers that can be wired
directly. What is it to power? Do you need DC or is AC ok?


It's for a servant call board, almost identical to this:
https://www.youtube.com/watch?v=VNZxBMfUmZ8. There's also a repeater
bell at the far end of the house.

It was running, very feebly, on AC. I experimented with a bench supply
and found that it's much happier with about 5V DC so found a 5V wart in
a box and added a 470uF cap inside the indicator box. The socket needs
to be 13A because of the wart plug.


I got better results with several thousand uF at the PSU end of the wire before the switch. Electromagnetic movements benefit from a good kick. That was running an old mercury switch dingdong.


NT
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On 03/01/2018 19:42, wrote:
On Wednesday, 3 January 2018 12:30:33 UTC, wrote:
On 03/01/2018 08:35, John Rumm wrote:
On 02/01/2018 23:10,
wrote:

I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?

Nothing wrong with it in principle. A 3A fuse would probably be more
useful.

You could also look at 2A plugs/sockets if you can't find a
PSU/transformer that can be wired directly. e.g:

https://www.tlc-direct.co.uk/Products/CB7046.html

Having said that, you can get neat bell transformers that can be wired
directly. What is it to power? Do you need DC or is AC ok?


It's for a servant call board, almost identical to this:
https://www.youtube.com/watch?v=VNZxBMfUmZ8. There's also a repeater
bell at the far end of the house.

It was running, very feebly, on AC. I experimented with a bench supply
and found that it's much happier with about 5V DC so found a 5V wart in
a box and added a 470uF cap inside the indicator box. The socket needs
to be 13A because of the wart plug.


I got better results with several thousand uF at the PSU end of the wire before the switch. Electromagnetic movements benefit from a good kick. That was running an old mercury switch dingdong.


NT

I didn't explain that well. The cap is inside the box but across the
output of the wart, if it was across the bell it would make things worse.
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On Wed, 3 Jan 2018 19:53:01 +0000, wrote:

I didn't explain that well.


Well, try something new

Crank Doorbell Circuit Schematic

http://www.electroschematics.com/6304/crank-doorbell/


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On Wednesday, 3 January 2018 21:28:19 UTC, Fredxx wrote:
On 03/01/2018 08:17, tabbypurr wrote:
On Wednesday, 3 January 2018 07:17:10 UTC, harry wrote:
On Tuesday, 2 January 2018 23:10:04 UTC, wrote:


I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?

Your door bell system with transformer uses a lot of energy.


How many batteries can you buy with say a years worth at a 10W load?


No newish wallwart quiesces at anywhere near 10W. Not even 1W now.
1W is about £1 a year, for which you can get a poundland pack of junk batteries or a few good ones.

The batteries are probably slightly cheaper if using electronic sounders, but you have to buy & replace them every so often, you'l get missed calls and the battery contacts will corrode sooner or later. In short it's a false economy, if it's an economy at all.


Consider getting a (wireless) battery replacement.


unwise


Maybe, you can have wired battery powered door bells.


Yes - the worst of both worlds.


NT
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On 03/01/2018 20:46, JAB wrote:
On Wed, 3 Jan 2018 19:53:01 +0000, wrote:

I didn't explain that well.


Well, try something new

Crank Doorbell Circuit Schematic

http://www.electroschematics.com/6304/crank-doorbell/


Not quite in keeping with the application, which is almost identical to
this: https://www.youtube.com/watch?v=VNZxBMfUmZ8. Each call button is
wired in series with an electromagnetic and then with the bell. The
electromagnet waggles a flag in a window to show which room has called
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In article ,
harry wrote:
On Wednesday, 3 January 2018 11:17:35 UTC, Dave Plowman (News) wrote:
In article ,
harry wrote:
Your door bell system with transformer uses a lot of energy.
Low power but on all the time.


And you think battery costs will be less?

The battery is only in use for a few seconds each week.
The transformer is continually drawing current


And how much current do you think it draws?

--
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Dave Plowman London SW
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On Thursday, 4 January 2018 11:42:17 UTC, Dave Plowman (News) wrote:
In article ,
harry wrote:
On Wednesday, 3 January 2018 11:17:35 UTC, Dave Plowman (News) wrote:
In article ,
harry wrote:
Your door bell system with transformer uses a lot of energy.
Low power but on all the time.

And you think battery costs will be less?

The battery is only in use for a few seconds each week.
The transformer is continually drawing current


And how much current do you think it draws?


the battery or the transformer, how about both

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On 03/01/2018 22:51, wrote:
On Wednesday, 3 January 2018 21:28:19 UTC, Fredxx wrote:
On 03/01/2018 08:17, tabbypurr wrote:
On Wednesday, 3 January 2018 07:17:10 UTC, harry wrote:
On Tuesday, 2 January 2018 23:10:04 UTC, wrote:


I need to replace an ancient bell/call box power supply with a modern
wallwart. The original transformer (from the 1930s, with internal fuses
in both L and N) was wired into the lighting circuit. It would be very
difficult to get non-lighting power to this location (near the ceiling,
in the kitchen), I don't have space for a fused spur and I can't find a
13A socket with a built-in fuse. I'm planning on using a standard 13A
socket, fitting an internal 500mA in-line fuse and adding a suitable
label to the socket.
What does the jury think?

Your door bell system with transformer uses a lot of energy.


How many batteries can you buy with say a years worth at a 10W load?


No newish wallwart quiesces at anywhere near 10W. Not even 1W now.
1W is about £1 a year, for which you can get a poundland pack of junk batteries or a few good ones.

The batteries are probably slightly cheaper if using electronic sounders, but you have to buy & replace them every so often, you'l get missed calls and the battery contacts will corrode sooner or later. In short it's a false economy, if it's an economy at all.


Consider getting a (wireless) battery replacement.

unwise


Maybe, you can have wired battery powered door bells.


Yes - the worst of both worlds.


NT

How do you make that out? I have a wired battery bell (two bells in
parallel actually), and don't have to change the alkaline C cells any
more often than their shelf life of 6 years.
--
Dave W
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On 03/01/2018 12:30, wrote:
It's for a servant call board, almost identical to this:
https://www.youtube.com/watch?v=VNZxBMfUmZ8. There's also a repeater
bell at the far end of the house.


Wife or kids ?. don't people just their phones or tablets
these days ?.
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In article , Andrew97d-
says...

Do US or continental wall warts plug into 5 amp round pin sockets
intended for lighting ?.


There is no such thing as a 5A socket in Europe but
continental wallwarts fit sockets both for the 2-pin 2.5A
'Europlug'

https://en.wikipedia.org/wiki/Europlug

as well as the standard 16A Schuko or its French/Belgian
variant.

https://en.wikipedia.org/wiki/Schuko

You may encounter 6A versions of the Europlug and matching -
usually multiple - sockets but they are not defined by any
standard.

No idea what they do in the US

--

Terry

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http://www.avg.com

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