Wiki: Doorbell wiring


M

meow2222

Another one for your condemnation...



This article covers choice and fitting of wired doorbells.


==Kit or self assembled==
Doorbell kits are easy, as you don't need to worry about voltage,
[[Electricity Basics|ac versus dc]], regulation or anything else. You
even get all the bits in one pack. If you're not too fussy, these pre-
packed kits make life easier.

Assembling your own system from diverse parts is more complex, but not
very difficult. And of course its much more flexible.


==Sounders==
You get a choice of
* Bell
* Ding dong
* Electronic

Mechanical sounders tend to produce voltage pulses on the [[Low
Voltage Wiring|cable]], so mixing electronic and mechanical sounders
on one circuit is not best practice, and may kill the electronic
sounder.

Generally speaking, and these aren't always the case:
* bells are the loudest
* dingdongs are medium volume, but much more pleasant to the ear
* electronic sounders can produce various sounds, but generally aren't
so loud.


==Switch==
The bell push is just a momentary switch. It doesn't matter whether
the switch goes in the -ve or +ve fead to the bell. Many also have a
low power [[Filament Lamps|filament bulb]] inside, which lights when
the switch isn't being pressed.

Since it switches low voltage at not much current, the switch can be
pretty much any type of momentary push-to-make switch. Custom switches
are perfectly DIYable where a character bellpush is wanted.

Improvement in switch reliability and longevity can be gained by
fitting a [[snubber]] across the switch contacts. This also eliminates
one of the causes of interference to audio equipment & digital TV.
Snubbers are not usually fitted, but if you put time into making a
fancy switch it makes sense to take another minute or 2 to make it
last.

Note that mains [[snubbers]] aren't effective for low voltage use.
More suitable component values would be 15-22 ohms plus 10uF (for dc
systems) or 15-22 ohms & 1uF non-polar for ac systems.

A [[Filament Lamps|filament bulb]] in the bellpush acts as a
[[snubber]], but these are often not fitted, and when they are they're
often not replaced when they fail. Snubbers last for life. [[LED
Lighting|LED lights]] in bellpushes don't act as snubbers.


==Circuit diagrams==

Mains
| |
____|__|_____
| | ______
| TRANSFORMER |------------------------------| |
| typically | | Bell |
| 6-8V AC |------+ +------------|______|
|_____________| | |
| |
| |
| |
| |
| |
| |
+--Switch--+

Basic system diagram


This can be optionally expanded as follows:

Mains
| |
____|__|_____
| |---+--------------------+---------+
| | | ___|__ ___|__
| TRANSFORMER | | | | | |
| | === C | Bell | | Bell |
| | | |______| |______|
| | | | |
|_____________|---+--+ +------+---------+
| Light |
| / \ |
+--Switch--+
| \ /|
| Snubber |
| |
| |
| Light |
| / \ |
+--Switch--+
| \ /|
| Snubber |
| |
| |
| Light |
| / \ |
+--Switch--+
\ /
Snubber

Circuit with optional extras



==Kit Power supplies==
The power supply in a kit will be chosen to match tbe sounder. These
are often ac transformers.

==Other power supplies==
If assembling your own system you'll need to do a bit hinking re the
power supply.

Standard bell transformers can be used with a lot of sounders, but not
all. They are the simple choice if your sounder will accept the ac
voltage the transformer produces. If it won't, the ac may kill the
sounder. The next section explains supplies for sounders requiring dc,
and how to run any sounder on a [[wallwart]]. (Ac sounders can run
happily on dc.)


For dc [[wallwart]] supplies:
* for electronic sounders, use a wallwart of the sounder's rated
voltage
* for mechanical sounders, use a 1A wallwart of 3v above the sounder's
rated voltage. Adding a 2200uF-4700uF 16v (or more) capacitor across
the transformer's outputs (connecting + to +, - to -) can improve
reliability & volume.

The above will work fine in nearly all cases.

===DC power supplies explained===
If you want to understand power supply choice properly, and pick the
optimum supply, here's the deal:

Electronic sounders use low power, and will run fine off the rated
voltage of supply. No capacitor is required.

Mechanical bells and ding-dongs use a lot of current when they're
sounding, well above the rated current of your average [[wallwart]].
This isn't a problem for the wart, since it only delivers this current
for a tiny percentage of the time. However it does have implications
for the sounder. The current draw results in the wart delivering well
below rated voltage during sounding, due to transformer copper losses.
This drop is partly made up for by picking a higher voltage wart.

An added issue is that mechanical sounders suffer from stiction and
some require an initial current & voltage kick to get them moving
freely, so they work well & give good volume. The capacitor delivers
this, by charging to above on-load voltage and delivering this to the
bell for a very brief moment when the bellpush is operated. This is
entirely harmless to mechanical sounders.

Most [[wallwarts]] deliver well above rated voltage when off load.
This doesn't matter to mechanical sounders since they're not
connected, and a momentary overvoltage when connected is beneficial
rather than harmful. [[Filament Lamps|Light bulbs]] however do care
very much about voltage, and the bellpush bulb should be rated at or
above the voltage the wart delivers when offload. A [[multimeter]]
will show the off load voltage. Hence ideally the bulb and bell will
have different voltage ratings, yet both be powered by the one supply.



==Wiring==
[[Low Voltage Wiring|Bell wire]] is the cheapest wire that will do the
job, and is the usual [[Low Voltage Wiring|cable]] used. In larger
properties, long runs of bell wire can affect operation with
mechanical sounders, the solution to this is simply to increase the
power supply output voltage to compensate.

Standard 4mm bell wire staples are used to fix the [[Low Voltage
Wiring|cable]] to the wall.

Although bells are low voltage circuits, mechanical sounders tend to
produce higher voltage pulses on the [[Low Voltage Wiring|cable]], so
use of bare [[Low Voltage Wiring|enamelled wire]] is not recommended.
For this reason, mixing electronic and mechanical sounders on one
circuit is not recommended, and can sometimes kill the electronic
sounder.


==Wireless bells==
Surprisingly these need no wiring.

Since they run on [[battery|batteries]] they tend to go flat. If you
haven't had any visitors in a while this might be why!


==Alternatives==
* Mechanical doorbell
* Door knocker


==See Also==
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]



[[Category:Electrical]]
 
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C

chrisj.doran

Another one for your condemnation...

This article covers choice and fitting of wired doorbells.
<snip>

The electronic type don't require much current to trigger the sounder.
A partial short in the wiring or rainwater in the bellpush may conduct
enough to make it sound for ever!

Chris
 
M

meow2222

Another one for your condemnation...

This article covers choice and fitting of wired doorbells.
thanks for the tips. Done a fair bit more on it....


This article covers the choice and fitting of wired doorbells.


==The options==
* Wired doorbell
* Wireless doorbell
* Mechanical doorbell
* Door knocker
* nothing


==Kits==
Doorbell kits are easy, as you don't need to worry about voltage,
[[Electricity Basics|ac or dc]], regulation or anything else. You even
get all the bits in one pack. If you're not fussy, pre-packed kits
make life simple. Kit systems tend to be basic, and a lot of the
sections about extra options in this article won't apply.

Usually the only thing you need to know with a kit is how to wire it
up. See the basic circuit [[Doorbell wiring#Circuit diagrams|here]].


==Self assembled systems==
Assembling your own system from diverse parts is more complex, but not
difficult. And of course its much more flexible, with more choices and
various extras available.


==Sounders==
You get a choice of
* Bell
* Chime (mechanical)
* Electronic sounder

Mechanical sounders tend to produce voltage pulses on the [[Low
Voltage Wiring|cable]], so mixing electronic and mechanical sounders
on one circuit is not best practice, and may kill the electronic
sounder.

As a general rule of thumb:
* Bells are the loudest
* Chimes are medium volume, but much more pleasant to the ear
* electronic sounders can produce various sounds, but generally aren't
so loud.


==Switch==
The bell push is just a momentary switch. It doesn't matter whether
the switch goes in the -ve or +ve feed to the bell.

Since it switches low voltage at not much current, the switch can be
pretty much any type of momentary push-to-make switch. Custom switches
are perfectly DIYable where a character bellpush is wanted.


==Light==
===Filament lamp===
Many bellpushes have a low power [[Filament Lamps|filament bulb]]
inside, which lights when the switch isn't being pressed. This
connects across the switch contacts. Such lamps are generally intended
for use with mechanical sounders, if used with electronic ones they
may cause continuous sounding.

===LED===
[[LED Lighting|LEDs]] aren't used in most bell systems, but
Ultrabright LEDs are a good long life replacement for bellpush
filament lamps. These are available in a number of colours as well as
white, they last in the region of 50,000 hours, they cost pence and
consume miniscule power.

2 such LEDs should be used, connected in inverse parallel, with a
series diode to limit current. When using LEDs with a mechanical
sounder, a snubber is also required to avoid premature LED failure.
LEDs with at least 1,000 mcd output are recommended.


+-----|>|-----+
-----| |-----^^^^-----
+-----|<|-----+

LEDs Resistor

For maximum brightness, 20mA LEDs require a resistor of:
* for an 8v dc supply:
** blue & white: 220 ohms
** green: 270 ohms
** red, orange, yellow: 330 ohms
* for an 8v ac supply:
** blue & white: 330 ohms
** green: 470 ohms
** red, orange, yellow: 470 ohms
* for a 6v dc supply:
** blue & white: 100 ohms
** green: 150 ohms
** red, orange, yellow: 220 ohms
* for a 6v ac supply:
** blue & white: 150 ohms
** green: 220 ohms
** red, orange, yellow: 330 ohms

A 20mA LED will consume 40-80mW, or 0.35-0.7kWh per annum, at a cost
of 3.5-10p per annum.

LED brightness can be reduced by using higher resistances. Twice the
resistance above gives around half the output and even longer LED
life.


==Snubber==
A snubber is not usually fitted, but if you put time into making a
fancy switch it makes sense to take another minute or 2 to make it
last.

Improvement in switch reliability and longevity can be gained by
fitting a [[snubber]] across the switch contacts. This also eliminates
one of the causes of interference to audio equipment & digital TV.

Snubbers make more difference with mechanical sounders, which are
invariably inductive loads, and thus hard on switch contacts.

Note that mains [[snubbers]] aren't effective for low voltage use.
More suitable component values would be:
* for dc systems: a 15-22 ohm resistors plus a 10uF capacitor.
* for ac systems: 15-22 ohms & a 1uF non-polar capacitor.

A [[Filament Lamps|filament bulb]] in the bellpush acts as a
[[snubber]], but these are often not fitted, and when they are they're
often not replaced when they fail. Snubbers last for life. [[LED
Lighting|LED lights]] in bellpushes don't act as snubbers, and require
snubbers with mechanical sounders.


==Circuit diagrams==

Mains
| |
____|__|_____
| | ______
| Transformer |------------------------------| |
| | | Bell |
| |------+ +------------|______|
|_____________| | |
| |
| |
| |
| |
| |
| |
+--Switch--+

Basic system diagram


This can be optionally expanded as follows:

Mains
| |
____|__|_____
| |---+--------------+---------+---------------+---------
+
| | | ___|__ ___|__ ___|__ ___|
__
| Transformer | | | | | | | |
| |
| | === C | Bell | | Bell | | Bell | |
Bell |
| | | |______| |______| |______| |
______|
| | | | | |
|
|_____________|---+---+ +---------+ +---------
+
| Light | Light |
| / \ | / \ |
+--Switch--+ +--Switch--+
| \ /| | \ /|
| Snubber | | Snubber |
| | | |
| | | |
| Light | | Light |
| / \ | | / \ |
+--Switch--+ +--Switch--+
| \ / | \ /
| Snubber | Snubber
|_________________________|

With optional extras


==Power supplies==

===Batteries===
A 6v lantern [[battery]] can be used, but one costs as much as a
[[wallwart]], so batteries are not often a pointful option.

Batteries are only workable with unlit bellpushes. Use of an
electronic sounder makes a battery last much longer.

The modern fashion is to cut manufacturing costs by using AA or PP3
batteries. These work, but have much shorter lives, and you end up
with repeated [[battery]] replacement and lots of missed calls. Over
the long term, small batteries are a false economy.


===Kit Power supplies===
The power supply in a kit will match tbe sounder.

===Other power supplies===
If assembling your own system you'll need to do a bit of thinking re
the power supply.

Standard bell transformers can be used with a lot of sounders, but not
all. These are ac output transformers, typically 5-8v. Mechanical
sounders usually use these. They're the simple choice if your sounder
will accept the ac voltage the transformer produces. If it won't, the
ac may kill the sounder. The next section explains supplies for
sounders requiring dc, and how to run any sounder on a [[wallwart]].
Ac sounders also run happily on dc (often requiring a bit less voltage
on dc).


For dc [[wallwart]] supplies:
* for electronic sounders, use a wallwart of the sounder's rated
voltage
* for mechanical sounders, use a 1A wallwart of 3v above the sounder's
rated voltage. Adding a 2200uF-4700uF 16v (or more) capacitor across
the transformer's outputs (connecting + to +, - to -) can improve
reliability & volume.

The above rule of thumb will work fine in nearly all cases.

====DC power supplies explained====
If you want to understand power supply choice properly, and pick the
optimum supply, here's the deal:

Electronic sounders use low power, and will run fine off the rated
voltage of supply. No capacitor is required.

Mechanical bells and ding-dong chimes use a lot of current when
they're sounding, well above the rated current of your average
[[wallwart]]. This isn't a problem for the wart, since it only
delivers this current for a tiny percentage of the time. However it
does have implications for the sounder. The current draw results in
the wart delivering well below rated voltage during sounding, due to
transformer copper losses. This drop is partly made up for by picking
a higher voltage wart.

An added issue is that mechanical sounders suffer from stiction and
some require an initial current & voltage kick to get them moving
freely, so they work well & give good volume. The capacitor delivers
this, by charging to above on-load voltage and delivering this to the
bell for a very brief moment when the bellpush is operated. This is
entirely harmless to mechanical sounders.

Most [[wallwarts]] deliver well above rated voltage when off load.
This doesn't matter to mechanical sounders since they're not
connected, and a momentary overvoltage when connected is beneficial
rather than harmful. [[Filament Lamps|Light bulbs]] however do care
very much about voltage, and the bellpush bulb should be rated at or
above the voltage the wart delivers when offload. A [[multimeter]]
will show the off load voltage. Hence ideally the bulb and bell will
have different voltage ratings, yet both be powered by the one supply.


===CU mounting===
Bell transformers that mount inside a CU are available. They cost more
to buy & more to fit.


==Wiring==
[[Low Voltage Wiring|Bell wire]] is the cheapest wire that will do the
job, and is the usual [[Low Voltage Wiring|cable]] used. In larger
properties, long runs of bell wire can affect operation with
mechanical sounders, the solution to this is simply to increase the
power supply output voltage to compensate.

Standard 4mm bell wire staples are used to fix the [[Low Voltage
Wiring|cable]] to the wall. Since its a low voltage system, there's no
requirement for insulated fixings, and other types of staples may also
be used.

Polarity doesn't matter for ac systems. With dc sounders it does. Bell
wire has a tiny ridge moulded along one edge, and this is used to
maintain correct polarity throughout the wiring.

Although door bells are low voltage circuits, mechanical sounders tend
to produce higher voltage pulses on the [[Low Voltage Wiring|cable]],
so use of bare [[Low Voltage Wiring|enamelled wire]] is not
recommended. For this reason, mixing electronic and mechanical
sounders on one circuit is not recommended, and can sometimes kill the
electronic sounder.


==Wireless bells==
Surprisingly these need no wiring. Since they run on [[battery|
batteries]] they tend to go flat. If you haven't had any visitors in a
while this might be why!


==Fault finding==
Bell circuits are very simple, and should present no difficulty if you
have a [[multimeter]] to see what's going on where. The one possible
surprise is that water in the bellpush can sometimes pass enough
current to operate an electronic sounder.


==See Also==
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]
* [http://www.rapidonline.com/Electronic-Components/Optoelectronics/
5mm-LEDs/5mm-Ultrabright-LEDs/77694/kw/ultrabright Ultrabright LEDs]



[[Category:Electrical]]
[[Category:Low Voltage]]
 
A

Andrew Gabriel

==Sounders==
You get a choice of
* Bell
* Chime (mechanical)
* Electronic sounder
Mechanical sounders tend to produce voltage pulses on the [[Low
Voltage Wiring|cable]], so mixing electronic and mechanical sounders
on one circuit is not best practice, and may kill the electronic
sounder.
As a general rule of thumb:
* Bells are the loudest
* Chimes are medium volume, but much more pleasant to the ear
* electronic sounders can produce various sounds, but generally aren't
so loud.
Some more tips...

Common doorbell sounds such as the "ding dong" chime bars tuned a
major third apart can easily be confused with the same sound on
TV/radio prorgams. This can become more problematic with aging
hearing where loss of directivity doesn't help distinguishing
where the chime came from. Choosing a more distinctive sounding
doorbell reduces the chance of this. If you already have chime bars,
swapping whem around (to give "dong ding") is an easy way to avoid
confusion with the TV/radio.

Hard of hearing...

Position one (or more) sounders in the rooms which people occupy,
rather than the hallway which might be closed off. Choose sounders
with a broad frequency output. Piezo electronic ones can produce
pretty much all sound at one frequency which the person may not be
very sensitive to, or several frequencies all above the person's
hearing cut-off frequency.

[Could do with a note about doorbells for the deaf]
===LED===
[[LED Lighting|LEDs]] aren't used in most bell systems, but
Ultrabright LEDs are a good long life replacement for bellpush
filament lamps. These are available in a number of colours as well as
white, they last in the region of 50,000 hours, they cost pence and
consume miniscule power.
You probably don't want something that dazzling.
The lights were originally just so you can read an illuminated
name in the dark. The filament lamps are well underrun and last
decades, usually longer than the bell push.

A snubber isn't the right way to protect an LED - you need a
diode to provide a current path for the back-EMF from the
operating coil.
==Power supplies==
===Batteries===
A 6v lantern [[battery]] can be used, but one costs as much as a
[[wallwart]], so batteries are not often a pointful option.
Batteries are only workable with unlit bellpushes. Use of an
electronic sounder makes a battery last much longer.
The modern fashion is to cut manufacturing costs by using AA or PP3
batteries. These work, but have much shorter lives, and you end up
with repeated [[battery]] replacement and lots of missed calls. Over
the long term, small batteries are a false economy.
IME, the first set of zinc carbon batteries lasted 10 years in my
door bell (until 6 years past their use-by date) with average use.
Second set hasn't run out yet. Difficult to justify a mains PSU in
such a case.
==Wiring==
[[Low Voltage Wiring|Bell wire]] is the cheapest wire that will do the
That's Extra Low Voltage Wiring (i.e. less than 50V).
[Low Voltage Wiring is standard mains wiring.]
 
B

Bill

Andrew Gabriel said:
Hard of hearing...

Position one (or more) sounders in the rooms which people occupy,
rather than the hallway which might be closed off. Choose sounders
with a broad frequency output. Piezo electronic ones can produce
pretty much all sound at one frequency which the person may not be
very sensitive to, or several frequencies all above the person's
hearing cut-off frequency.

I am slightly hard of hearing and ended up putting a bell in the lounge
and a "sound bomb" on the upstairs landing. I never miss the door "bell"
now!!

http://www.tlc-direct.co.uk/Products/TSSB2.html

It is also audible outside the front door so people using it know that
it has worked.
 
G

Graham.

One doorbell manufacturer, which is now part of Honeywell made an iconic
bell-push with an illuminated nameplate.

Clusters of these can still be seen festooned*
at the entrances to blocks of flats. This could be seen as a security
risk as it put the door-to-door pikies at an advantage.
Perhaps, for this reason the default
name was left in them, but then what if your surname really is Friedland?


*pun most defiantly intended
 
A

Andrew Gabriel

I am slightly hard of hearing and ended up putting a bell in the lounge
and a "sound bomb" on the upstairs landing. I never miss the door "bell"
now!!
How often do you open the door, only to see the caller fleeing
down the driveway as fast as they can? ;-)
It is also audible outside the front door so people using it know that
it has worked.
Actually, having positive feedback to the caller is important,
so they know the bell actually works.
 
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J

Jeremy Nicoll - news posts

Frank Erskine said:
If you fit an illuminated bellpush it's best to run the bell off a
transformer, or the battery will be flat in a very short time!
Does anyone know of a decent quality, preferably brass, circular bellpush
that has a bulb in it, where one can easily get replacement bulbs? I found
the bulbs in my Friedland system only lasted a couple of years each. New
bulbs had to come from Friedland themselves, which was a pain...
 
A

Appin

The message <geudncBA4cso8HzVnZ2dnUVZ8sPinZ2d@posted.plusnet>
I would not recommend wallwarts. Most aren't intended for long-term use
without overheating.

Things have changed -- most of the are now switched mode power supplies
and run a whole lot cooler than the nasty little transformers did. A
good quality one should last a reasonable length of time.
 
M

meow2222

The message <geudncBA4cso8HzVnZ2dnUVZ8sPin...@posted.plusnet>
I was puzzled when I read that, as long term use is exactly what most
warts do. Having reused various warts over the years I've never
encountered one that fried itself just from being left plugged in. And
from a legal point of view its clear that they do need to operate
safely when left plugged in.


NT
 
A

Andrew Gabriel

I was puzzled when I read that, as long term use is exactly what most
warts do. Having reused various warts over the years I've never
encountered one that fried itself just from being left plugged in. And
from a legal point of view its clear that they do need to operate
safely when left plugged in.
I was just posting more or less exactly the same, when I saw yours.

Many of them are horribly inefficient, but that's not the same
as being unreliable or unsafe.

I have for some time thought there should be EU requirements on
efficiency and off-load consumption of wall-warts (given they are
mostly left plugged in all the time). Some countries have imposed
these, and hence you'll find some (such as newer mobile phone
chargers) are high efficiency and virtually no power consumption
when off-load (so no need to unplug). These never get warm.
 
A

Andrew Gabriel

Just two minutes ago I was looking at the wall-wart for my Tomtom
SatNav - Its output is 5V at 2A max, yet it's rated at 25-34 VA. It's
labelled as 'efficiency level III', whatever that's supposed to
mean...
External Power Supply International Efficiency Marking Protocol...
http://www.psma.com/ul_files/forums/energy/July2005EPSInternationalEfficiencyMarkingProtocol_rev2.pdf

("International" is stretching it a bit -- it's really just
Australia and California, and they claim some buy-in from
China.)

and
 
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T

The Medway Handyman

Andrew said:
==Sounders==
You get a choice of
* Bell
* Chime (mechanical)
* Electronic sounder
Mechanical sounders tend to produce voltage pulses on the [[Low
Voltage Wiring|cable]], so mixing electronic and mechanical sounders
on one circuit is not best practice, and may kill the electronic
sounder.
As a general rule of thumb:
* Bells are the loudest
* Chimes are medium volume, but much more pleasant to the ear
* electronic sounders can produce various sounds, but generally
aren't so loud.
Some more tips...

Common doorbell sounds such as the "ding dong" chime bars tuned a
major third apart can easily be confused with the same sound on
TV/radio prorgams. This can become more problematic with aging
hearing where loss of directivity doesn't help distinguishing
where the chime came from. Choosing a more distinctive sounding
doorbell reduces the chance of this. If you already have chime bars,
swapping whem around (to give "dong ding") is an easy way to avoid
confusion with the TV/radio.

Hard of hearing...

Position one (or more) sounders in the rooms which people occupy,
rather than the hallway which might be closed off. Choose sounders
with a broad frequency output. Piezo electronic ones can produce
pretty much all sound at one frequency which the person may not be
very sensitive to, or several frequencies all above the person's
hearing cut-off frequency.

[Could do with a note about doorbells for the deaf]
I 'installed' a wirefree doorbell recently which had the option of a bright
flashing strobe type light as well as about a dozen different sounds. You
would have to be clinically dead not to be aware of it.
 

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