Wiki: Doorbell wiring

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.
==ά 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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On Mon, 29 Sep 2008 06:10:22 -0700 (PDT), snipped-for-privacy@care2.com wrote:

<snip>
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!
--
Frank Erskine

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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...
--
Jeremy C B Nicoll - my opinions are my own.

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wrote:

Replace it with a LED?
--
*I am a nobody, and nobody is perfect; therefore I am perfect*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 29 Sep, 15:10, snipped-for-privacy@care2.com wrote:

<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
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fead /feed?
mark
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On Sep 29, 2:10 pm, snipped-for-privacy@care2.com wrote:

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]]
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     snipped-for-privacy@care2.com writes:

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]

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.

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.

That's Extra Low Voltage Wiring (i.e. less than 50V). [Low Voltage Wiring is standard mains wiring.]
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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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.
--
Bill

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How often do you open the door, only to see the caller fleeing down the driveway as fast as they can? ;-)

Actually, having positive feedback to the caller is important, so they know the bell actually works.
--
Andrew Gabriel
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The big snag with many doorbells - other than an underdome bell - is that they simply aren't loud enough once your hearing starts deteriorating with age. And the common electronic types are the worst offenders.
--
*They call it PMS because Mad Cow Disease was already taken.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Andrew Gabriel wrote:

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.
--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
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A strobe might be fine if you live in a bedsit...
And I'll bet it's nothing like as loud as a standard underdome bell.
--
*Pride is what we have. Vanity is what others have.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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snipped-for-privacy@care2.com wrote:

Series resistor
Owain
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snipped-for-privacy@care2.com wrote:

* Buzzer
Some chimes have a second set of terminals for a back door.
If a really loud bell is required then 'fire bells' which run off or 24Vdc can be used.

Most bell-pushes are of fairly poor quality, but momentary (push-to-make) switches are available in the larger electrical accessory ranges, such as MK, including standard plateswitch, architrave switch, and weatherproof/external. Momentary pull-cord switches are also available.
Rubber tubing connected to a pneumatic switch can be used on petrol station forecourts, etc, to ring when a vehicle drives over it.
Over-door switches are available for shop bells.

How to put a switch in so one bell can be turned on/off.
Indicators - do people still use these?

I would not recommend wallwarts. Most aren't intended for long-term use without overheating.
Owain
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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.
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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
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     snipped-for-privacy@care2.com writes:

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.
--
Andrew Gabriel
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On 30 Sep 2008 16:48:01 GMT, snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote:

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...
--
Frank Erskine

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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
--
Andrew Gabriel
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