Old Door bell how does it work? - UK Vintage Radio Repair and Restoration Discussion Forum

Pete_kaye · 5th Jan 2014, 3:20 pm

I was given some old 1970s radio stuff but in the box was a door bell from that era. It works if I connect a charged 6v battery but takes about 1.5 A. It's resistance is about 4 R.
After a few tries the battery was flat. How should it be wired up ?. From the mains via a transformer giving 6v? Or is there more to it?

Radio Wrangler · 5th Jan 2014, 3:46 pm

Some doorbells were battery powered, but those usually had internal battery holders.

Mains powered doorbells used step-down isolating transformer. I think the usual 1960s Friedland transformer had taps for 4,6,9v. The bells worked on AC, and the inductance of their coils plus the copper resistance set the working current to something reasonable.

If you applied 6v DC to a bell intended for AC drive, you would get a lot of current being taken as there would be no inductive reactance, just the copper resistance.

David

Dave Moll · 5th Jan 2014, 3:48 pm

If its resistance is 4 ohms, then Ohm's Law does indeed mean that it will draw 1.5A. I though that this sounded rather a low resistance, but I've just measured my door chime as 6 ohms - and it has got through two sets of batteries (four "C" cells) in the 25 years that I've lived here. OK, I don't get a constant stream of callers, but has certainly clocked rather more than "a few" tries (or even "a few" times three to give the quivalent usage!) in that time.

What sort of 6V battery are you using?

Dave Moll · 5th Jan 2014, 3:56 pm

Quote:

Originally Posted by Radio Wrangler

If you applied 6v DC to a bell intended for AC drive, you would get a lot of current being taken as there would be no inductive reactance, just the copper resistance.

Also, I wouldn't have expected an AC bell to work on DC - other than a "ping" on connection and another on disconnection.

If it is a DC bell, it will have a "trembler" mechanism - a spring that makes contact until voltage is applied, then breaks the circuit once the voltage is applied, thus causing a continuous making and breaking to move the clapper back and forth. An AC bell (such as is used in a telephone) can vibrate the clapper using the alternation of the current itself.

Cobaltblue · 5th Jan 2014, 4:04 pm

I am wondering if its intended to work from 6V

If it is a DC bell it would be intended to work off sizeable dry batteries

A lot of very old bells were intended to work from a pair of Leclanché cells. (3 Volts)

I have somewhere an old wooden baseboard bell with cotton covered wire coils and it easily works down to 1.5V.

Cheers

Mike T

russell_w_b · 5th Jan 2014, 4:30 pm

Some a.c. bells have trembler mechanisms and many bells state a.c / d.c working. The larger ironclad 'Gents of Leicester' bells have laminated armatures (as well as a trembler) for a.c. working.

Typical two-bobbin bell resistances are 5, 6, 7, 8.5, 10 Ohms for gong sizes 3, 3.5, 4, 5, 6-inch respectively.

My trembler-bell annunciator works fine off a.c.

Mr Moose · 5th Jan 2014, 5:27 pm

Hello,

Most doorbells would work of mains, with a transformer,or battery.

In the 1970s the most common bell battery was a 4.5V battery with two screw terminals on top. (See picture below) The three cells in the battery were about the same diameter as a "D" cell but much taller so could supply a decent current.
This would give about 1A into a 4 ohm bell coil but the current taken by the bell is not continuous as it is interrupted by the contacts in the bell so the average current would probably be half an amp or less. The batteries usually lasted for several years.

There were bell transformers and a common type would have an 8V winding tapped at 3V to give voltages of 3V, 5V or 8V at about 1A and you chose the voltage which worked best.

Yours Richard

Pete_kaye · 5th Jan 2014, 5:56 pm

The battery I used was an old rechargeable house alarm back up battery , now scrapped. I will post a photo in a day or two. Mine isn't so old.

Herald1360 · 5th Jan 2014, 6:25 pm

Alarm backup batteries are usually something like 6V 1.2AH ISTR. A good one of those should deliver 1.5A for maybe 15 minutes. One that's a bit tired and lost capacity might well only last a few minutes....

In doorbell service it might see maybe 10 seconds use a day, but it wouldn't be a good solution unless it was on trickle charge, lead acids don't take to being left in a (partially) discharged state for extended periods very well at all.

Heatercathodeshort · 6th Jan 2014, 6:38 pm

Customers used to bring in those old 126 bell batteries for replacement and many were over 30 years old. 'I bet you haven't got one of these?' I bet I have! It was one of Ever Ready's oldest batteries and one of the last of the specialist types to fade from the lists. [PS Customers often wrote the date of installation on them] John.

Pete_kaye · 6th Jan 2014, 7:37 pm

Here is a photo of it .there are not many markings.

McMurdo · 6th Jan 2014, 8:14 pm

does it go brrring or just ding on your battery? It looks a bit like those ac bells you got in field telephones.
Be careful playing wth lead acid alarm batteries, they can set fire to anything they dont like.

Pete_kaye · 6th Jan 2014, 8:18 pm

It made a continuous 'brrring' before wearing out the battery . Not just a 'ping'. Could it be telephone bell ?

russell_w_b · 6th Jan 2014, 8:37 pm

It's just an ornery underdome a.c / d.c. doorbell-type bell, with a trembler beneath the base. It's not a telephone bell.

You must have a dodgy battery.

By comparison, one of my Gents underdome bells (single bobbin) has a d.c. resistance of 3.3 Ohms. The bell is designed for a supply of 4.5 - 6V d.c. and 8V a.c.

russell_w_b · 6th Jan 2014, 8:57 pm

Quote:

Originally Posted by McMurdo

It looks a bit like those ac bells you got in field telephones

It certainly does, from outside! But the sort of field telephone bell to which you refer (as found on a Type 'D') has the traditional type 59A dual-bobbin polarised bell-motor beneath the dome, with the clapper acting side-ways.

Quote:

Originally Posted by Mr Moose

but the current taken by the bell is not continuous as it is interrupted by the contacts in the bell so the average current would probably be half an amp or less.

350mA for a 3.3 Ohm bell designed for 4.5 - 6V d.c. or 8V a.c, when powered by a 4.5V battery.

I couldn't resist checking!

Quote:

Originally Posted by Pete_kaye

'...there are not many markings.'

Are there any markings, out of curiosity? If so, what do they say?

broadgage · 8th Jan 2014, 9:49 am

As others post, most door bells used domestically, or in similar size premises used a 4.5 volt door bell battery, or a slightly higher AC voltage from a transformer.

Prior to the general availability of cheap and reliable dry batteries, wet leclanche cells were used. The number of cells required varied, but 3 cells was very common.

It should be noted that the thin wire used for door bell circuits has significant resistance and that the actual operating current will therefore be much less than suggested by the resistance of the bell.

In the case of large premises a higher voltage supply was often required to overcome the resistance of the long wire runs.
12 volts AC from a suitable transformer or about 6 Leclanche cells being popular.
Large premises often implied relatively frequent use of the bells, and the 4.5 volt domestic door bell batteries would have a short life in frequent use. Flag cells being popular for large installations.

russell_w_b · 8th Jan 2014, 11:16 am

Quote:

Originally Posted by broadgage

Large premises often implied relatively frequent use of the bells, and the 4.5 volt domestic door bell batteries would have a short life in frequent use. Flag cells being popular for large installations.

I have a copy of Herbert G. White's book 'Electric Bells Alarms and Signalling Sytems' from about 1923 in which all this is explained. I also note from a contemporaneous dry cell advertisement (Sunco), a particular brand of cell stressing 'good recovery characteristics'.

H.G. White's book contains an illustration of a mains dropper for bell circuits using a potential divider, part of which is an incandescent lamp! Any 'bellorak' would be well advised to obtain a copy of this little book.

Brigham · 8th Jan 2014, 1:54 pm

Ordered! Thanks for the tip.

Pete_kaye · 9th Jan 2014, 7:45 pm

The only markings on mine are' SEKO 1600'.

emeritus · 10th Jan 2014, 11:46 pm

The electric bells section of the 1893 GEC catalogue gives 5 ohms as the mean resistance of ordinary bells. Telephone bells were wound to 25 ohms. Bells for long distance use were available wound to 25, 50 and 100 Ohms. Wet Leclanché cells were specified as having a 1.60V EMF, and the internal resistance of 1 pint, 2 pint and 3 pint cells was 1.50, 1.10 and 0.75 ohms respectively. Ah capacity was not stated. Dry batteries of the Flag type were available in several sizes, but were more expensive than the Wet Leclanche types.

5th Jan 2014, 3:20 pm	#1
Pete_kaye Octode Join Date: Jun 2005 Location: Sheffield, South Yorkshire, UK. Posts: 1,227	Old Door bell how does it work? I was given some old 1970s radio stuff but in the box was a door bell from that era. It works if I connect a charged 6v battery but takes about 1.5 A. It's resistance is about 4 R. After a few tries the battery was flat. How should it be wired up ?. From the mains via a transformer giving 6v? Or is there more to it?

5th Jan 2014, 3:46 pm	#2
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,874	Re: Old Door bell how does it work? Some doorbells were battery powered, but those usually had internal battery holders. Mains powered doorbells used step-down isolating transformer. I think the usual 1960s Friedland transformer had taps for 4,6,9v. The bells worked on AC, and the inductance of their coils plus the copper resistance set the working current to something reasonable. If you applied 6v DC to a bell intended for AC drive, you would get a lot of current being taken as there would be no inductive reactance, just the copper resistance. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

5th Jan 2014, 3:48 pm	#3
Dave Moll Dekatron Join Date: Feb 2005 Location: West Cumbria (CA13), UK Posts: 6,127	Re: Old Door bell how does it work? If its resistance is 4 ohms, then Ohm's Law does indeed mean that it will draw 1.5A. I though that this sounded rather a low resistance, but I've just measured my door chime as 6 ohms - and it has got through two sets of batteries (four "C" cells) in the 25 years that I've lived here. OK, I don't get a constant stream of callers, but has certainly clocked rather more than "a few" tries (or even "a few" times three to give the quivalent usage!) in that time. What sort of 6V battery are you using? __________________ Mending is better than Ending (cf Brave New World by Aldous Huxley)

5th Jan 2014, 4:04 pm	#5
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,865	Re: Old Door bell how does it work? I am wondering if its intended to work from 6V If it is a DC bell it would be intended to work off sizeable dry batteries A lot of very old bells were intended to work from a pair of Leclanché cells. (3 Volts) I have somewhere an old wooden baseboard bell with cotton covered wire coils and it easily works down to 1.5V. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk Last edited by Cobaltblue; 5th Jan 2014 at 4:06 pm. Reason: Just spotted the 70's refference

5th Jan 2014, 4:30 pm	#6
russell_w_b Dekatron Join Date: Jul 2007 Location: Penrith, Cumbria, UK. Posts: 3,687	Re: Old Door bell how does it work? Some a.c. bells have trembler mechanisms and many bells state a.c / d.c working. The larger ironclad 'Gents of Leicester' bells have laminated armatures (as well as a trembler) for a.c. working. Typical two-bobbin bell resistances are 5, 6, 7, 8.5, 10 Ohms for gong sizes 3, 3.5, 4, 5, 6-inch respectively. My trembler-bell annunciator works fine off a.c. __________________ Regds, Russell W. B. G4YLI.

5th Jan 2014, 5:27 pm	#7
Mr Moose Octode Join Date: Jul 2008 Location: Gloucestershire, UK. Posts: 1,043	Re: Old Door bell how does it work? Hello, Most doorbells would work of mains, with a transformer,or battery. In the 1970s the most common bell battery was a 4.5V battery with two screw terminals on top. (See picture below) The three cells in the battery were about the same diameter as a "D" cell but much taller so could supply a decent current. This would give about 1A into a 4 ohm bell coil but the current taken by the bell is not continuous as it is interrupted by the contacts in the bell so the average current would probably be half an amp or less. The batteries usually lasted for several years. There were bell transformers and a common type would have an 8V winding tapped at 3V to give voltages of 3V, 5V or 8V at about 1A and you chose the voltage which worked best. Yours Richard Attached Thumbnails

5th Jan 2014, 5:56 pm	#8
Pete_kaye Octode Join Date: Jun 2005 Location: Sheffield, South Yorkshire, UK. Posts: 1,227	Re: Old Door bell how does it work? The battery I used was an old rechargeable house alarm back up battery , now scrapped. I will post a photo in a day or two. Mine isn't so old.

5th Jan 2014, 6:25 pm	#9
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Old Door bell how does it work? Alarm backup batteries are usually something like 6V 1.2AH ISTR. A good one of those should deliver 1.5A for maybe 15 minutes. One that's a bit tired and lost capacity might well only last a few minutes.... In doorbell service it might see maybe 10 seconds use a day, but it wouldn't be a good solution unless it was on trickle charge, lead acids don't take to being left in a (partially) discharged state for extended periods very well at all. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

6th Jan 2014, 6:38 pm	#10
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Old Door bell how does it work? Customers used to bring in those old 126 bell batteries for replacement and many were over 30 years old. 'I bet you haven't got one of these?' I bet I have! It was one of Ever Ready's oldest batteries and one of the last of the specialist types to fade from the lists. [PS Customers often wrote the date of installation on them] John.

6th Jan 2014, 7:37 pm	#11
Pete_kaye Octode Join Date: Jun 2005 Location: Sheffield, South Yorkshire, UK. Posts: 1,227	Re: Old Door bell how does it work? Here is a photo of it .there are not many markings. Attached Thumbnails

6th Jan 2014, 8:14 pm	#12
McMurdo Dekatron Join Date: Jun 2009 Location: Staffordshire Moorlands, UK. Posts: 5,271	Re: Old Door bell how does it work? does it go brrring or just ding on your battery? It looks a bit like those ac bells you got in field telephones. Be careful playing wth lead acid alarm batteries, they can set fire to anything they dont like. __________________ Kevin

6th Jan 2014, 8:18 pm	#13
Pete_kaye Octode Join Date: Jun 2005 Location: Sheffield, South Yorkshire, UK. Posts: 1,227	Re: Old Door bell how does it work? It made a continuous 'brrring' before wearing out the battery . Not just a 'ping'. Could it be telephone bell ?

6th Jan 2014, 8:37 pm	#14
russell_w_b Dekatron Join Date: Jul 2007 Location: Penrith, Cumbria, UK. Posts: 3,687	Re: Old Door bell how does it work? It's just an ornery underdome a.c / d.c. doorbell-type bell, with a trembler beneath the base. It's not a telephone bell. You must have a dodgy battery. By comparison, one of my Gents underdome bells (single bobbin) has a d.c. resistance of 3.3 Ohms. The bell is designed for a supply of 4.5 - 6V d.c. and 8V a.c. __________________ Regds, Russell W. B. G4YLI.

8th Jan 2014, 9:49 am	#16
broadgage Nonode Join Date: Jan 2010 Location: North Somerset, UK. Posts: 2,129	Re: Old Door bell how does it work? As others post, most door bells used domestically, or in similar size premises used a 4.5 volt door bell battery, or a slightly higher AC voltage from a transformer. Prior to the general availability of cheap and reliable dry batteries, wet leclanche cells were used. The number of cells required varied, but 3 cells was very common. It should be noted that the thin wire used for door bell circuits has significant resistance and that the actual operating current will therefore be much less than suggested by the resistance of the bell. In the case of large premises a higher voltage supply was often required to overcome the resistance of the long wire runs. 12 volts AC from a suitable transformer or about 6 Leclanche cells being popular. Large premises often implied relatively frequent use of the bells, and the 4.5 volt domestic door bell batteries would have a short life in frequent use. Flag cells being popular for large installations.

8th Jan 2014, 1:54 pm	#18
Brigham Octode Join Date: Mar 2006 Location: Co. Durham, UK. Posts: 1,117	Re: Old Door bell how does it work? Ordered! Thanks for the tip.

9th Jan 2014, 7:45 pm	#19
Pete_kaye Octode Join Date: Jun 2005 Location: Sheffield, South Yorkshire, UK. Posts: 1,227	Re: Old Door bell how does it work? The only markings on mine are' SEKO 1600'.

10th Jan 2014, 11:46 pm	#20
emeritus Dekatron Join Date: Jan 2012 Location: Brentwood, Essex, UK. Posts: 5,339	Re: Old Door bell how does it work? The electric bells section of the 1893 GEC catalogue gives 5 ohms as the mean resistance of ordinary bells. Telephone bells were wound to 25 ohms. Bells for long distance use were available wound to 25, 50 and 100 Ohms. Wet Leclanché cells were specified as having a 1.60V EMF, and the internal resistance of 1 pint, 2 pint and 3 pint cells was 1.50, 1.10 and 0.75 ohms respectively. Ah capacity was not stated. Dry batteries of the Flag type were available in several sizes, but were more expensive than the Wet Leclanche types.