Frustrations arising from adding a second door bell

[PaulS]

Hi Everyone,

I have a frustrating door bell extension situation.

When the house was rewired many years ago a cable (bog standard 2 core bell wire) was passed through the cavity / under floors from the under-the-stai rs transformer adjacent to the breaker panel, to the front door bell push v ia an over the door bell

dome-bell-brass/14337) providing a simple door bell setup.

Mains | | ____|__|_____ | | ______ | Transformer |------------------------| | | | | Bell | | 8VAC |---------Switch---------|______| |_____________|

When I built my office I ran a cable from a second bell in the office back to the under-the-stairs panel. From past experience I knew i wouldn't be ab le to hear the existing bell when working.

Initially I tested each bell individually - both ring when they're the only one on the circuit. I then wired the bells in series. No sound. I hadn't r eally expected them to as the 8 Volt transformer wouldn't have the oomph to drive 2 bells in series.

______ Mains | | | | | Bell | ____|__|_____ |______| | | | | ______ | Transformer |-----| |-------------| | | | | Bell | | 8VAC |---------Switch---------|______| |_____________|

I replaced the 8 Volt transformer with a transformer tapped at 8, 16 and 24 and tried again. Still no go.

______ Mains | | | | | Bell | ____|__|_____ |______| | | | | ______ | Transformer |-----| |-------------| | | | | Bell | | 16-24VAC |---------Switch---------|______| |_____________|

The bells are similar and when poked with my multimeter I can see what appe ars to be an adequate voltage across the terminals (testing from where the wires terminate near the transformer).

My next thought was that it might be something to do with the way the bell mechanisms work - making and breaking the circuit and that being out of syn c in such a way as to prevent either bell from working - so I modified the circuit and added a 12VAC relay.

______ ______ Mains | |------------| | | | | Relay| | Bell | ____|__|_____ |______|------------|______| | | | | ______ | Transformer |-----| |-------------| | | | | Bell | | 16-24VAC |---------Switch---------|______| |_____________|

When the bell push is pressed, the relay operates, but the bell in series w ith it doesn't. Frustrating!

Somewhere in the dim recesses of my memory I can recall adding a capacitor in parallel to an inductive load (such as the bell or the relay) might be o f some use in such situations. But what type of capacitor and what value? A nyone?

Could anyone explain precisely why the original 2 bells in series with what appears to be adequate voltage and the bell and relay in series don't work ?

Any other novel solutions I might use given that:

- There is only one 2 core wire in place to the front door where the first bell and switch (bell push) are and no option of adding another.

- There is only one 2 core wire to the second bell.

- I only have access to the wires where they terminate near the transformer . This in effect means I CAN'T wire the bells in parallel.

- Wireless is not an option. I need a fix and forget set-up with no batteri es.

Long read I know, so thanks for reading.

I'd welcome some words of wisdom / experience of similar situations.

[Harry Bloomfield]

PaulS presented the following explanation :

The two bells need to be wired in parallel with each other and supplied with their correct working voltage.

[Brian-Gaff]

Are these AC bells or DC bells, from what you say of using a relay, one supposes dC are they chimes or actual mechanical bells? Personally in any bell I'd wire them in parallel and get a transformer rated for a higher load and that should work. Brian

[Max Demian]

I think you would normally have to wire them in parallel for it to work. Maybe if you shorted out the contact of the second bell it might work in series.

[Brian-Gaff]

I just do not see any other way than wiring in parallel. Surely it only needs one more wire, and it does not even need to go the same route. Brian

[Chris Hogg]

As others have said, wire the bells in parallel. If it takes 8 volts to activate a bell and you wire two in series, you're only going to get 4 volts across each bell, so neither will work, although I would have expected them to work from the bigger transformer, assuming that you've tapped off at 16v and the transformer could supply the necessary current. When you tested the volts on that bigger transformer, did you have the bell-push pressed? I suspect not, and if you had done, you might have found the voltage dropped significantly.

But even if you do wire the bells in parallel, the original transformer still might not have enough oomph to activate both bells. Do the bells say what current they take, and does your original transformer say what it can supply?

[spuorgelgoog]

With the relay, where is the additional bell getting its current from?

Trembler bells wired in series will *not* work.

The 'standard' way to run trembler bells in series is to short the interrupter contacts on the second bell(s). Thus both bells respond to the make-and-break generated by the first bell's interrupter.

You may need to add a snubber across the first bell's interrupter as it'll be handling a larger than intended inductive load.

I prefer Friedland or Gent bells to Byron.

Owain

[newshound]

By far the best fix that I have found is to use wireless bells for the extension(s). Whilst the instructions say that the "sender" should just be connected to the bell push, mine actually works fine connected across a bell push that is operating a traditional transformer / bell setup.

Bells are either battery or plug into mains.

Byron are probably the "gold standard" but there are cheap clones around. Some of the better ones have a choice of frequencies if you have lots of bells in the neighbourhood. Some of them have a surprisingly long range (obviously more chance of interference in that case).

[tabbypurr]

Bingo. But realise that the 2 may tremble at different speeds, in which case you need to let the slower trembler run & short the faster. IIRC this is all covered in the wiki doorbell article.

NT

[Steve Walker]

Bells powered from transformers are usually AC (but most would work fine on DC). There are plenty of relays designed to have their coils operated by AC.

SteveW

[Terry Casey]

So, just to clarify, your original wiring actually looks like this?

Mains | | ____|__|_____ | | Joint ______ | Transformer |------------x-----------| | | | | Bell | | 16-24VAC |---------| |---------|______| |_____________| | | | | |-/--| Switch

If so, your only chance is, as others have already said, to short out the interrupter in one of the bells.

If that doesn't work first time - you might have to adjust the gong/clapper arrangement in the slave bell, try it the other way round so thst the master becomes the slave and vice-versa.

Idea!

If that doesn't work, try this:

you will need a transformer, a silcon diode, an electrolytic capacitor, a relay and a battery.

Connect the transformer seciondary in series with the output of the transformer. One side of the primary should be connected to the end of the diode which doesn't have a stripe or coloured band and the other end of the diode to the positive side of the electrolytic. The negative is then connecyed to the other side of the primary.

Now connect the relay coil across the electrolytic. Press the bell and ensure that, when the relay operates, the contacts remain closed until the bell is stopped. If the contacts open and close in time with the bell, you'll need a larger capacitor.

Connect the slave bell and the battery in series with the relay contacts. The slave should now ring at the same time as the master.

Like this:

________ D ______ | |----->|----|----| | | TR | |+ | Bell | | | C --- |______| | | --- ___|___ |________|---| | | | | | | | | Batt | |______| --------|----|______| | | | | | Relay| ____|__|_____ |______| | | | | ______ | Transformer |-----| |-------------| | | | | Bell | | 16-24VAC |---------Switch---------|______| |_____________|

[Brian Gaff]

Well, yes but they do tend to chatter. I have to say, most bells I've had have used DC, raw, but still DC. I guess it depends on what you buy.

I'm still Trying to understand the wiring here and why one cannot put them across each other. Brian

[Brian Gaff]

Interesting concept, In my experience this then just buzzes a bit. Brian

[Brian Gaff]

If the bells will work on DC how about putting a large current diode in anti phase so to speak across each bell, then one half cycle will run one bell and the other half cycle the other bell. Brian

[Brian Gaff]

Well all I can say is that when I tried this some time back the same bell nearly always, just buzzed. I imagine it might work if both are exactly the same bells with the windings the same. Brian

[Johnny B Good]

Paul's explained his problem quite fully in words, along with some ASCII art to show the wiring schematic. The schematics are a little redundant since the words paint, in this case, an adequate picture. :-)

However, to cut to the chase, his problem is that the wire from the second bell is going to where the transformer is located. It would be quite simple to wire them in parallel if the wire from the second bell had gone to the first one but it doesn't, hence the series arrangement along with a transformer upgrade to a higher voltage one to compensate for the series circuit arrangement of the bells being attempted in this case.

Presumably these are both (identical?) trembler bells so it's possible that both bells are in need of adjustment to balance up their current demands. Even so, they'll each need a suitably rated resistor wired across them to dampen down the effects of the current pulses being generated in the bell circuit by the interrupter contacts. A resistor value of one and a half times the bell coil resistance would be a good starting point but you might need to match the resistors to that of the bell coil resistances and accept the penalty of a higher current demand being placed on the bell transformer.

Otoh, if the bells in question aren't identical units, then it may simply be a case that the second bell is a lower resistance type that demands much more current from the bell transformer than the original bell required. Such a mismatch won't be helped by the current pulses generated by the first bell which may well be reducing the duty cycle as it receives more voltage from the higher voltage transformer being used, effectively limiting the average current available to the other bell in spite of the higher voltage being applied. Given enough of a mismatch, the lower resistance bell won't be receiving enough current to operate its interrupter contacts in this case.

[Johnny B Good]

In principal, that only stands a chance of success if both bells are identical and, more importantly, you can 'tune' the hammer/bell combination to match the resonant frequency of the hammer/bell combo of the driver bell.

[Jeff Layman]

I wonder why the OP won't/can't use a wireless bell?

We had a cheap wireless doorbell and it was junk - the bell ate AA batteries. It was replaced by a Friedland with one mains bell and one battery bell. The latter hasn't needed new batteries in over 2 years.

[Martin Brown]

And sufficient current to work too. Solenoid based ding-dong bells can draw a surprisingly high pulse of current and the original transformer may not be man enough to deliver enough current for two of them.

I have a loud piezo-electric self contained beeper as my office repeater which presents a minimal load to the original circuit.

[Terry Casey]

Now that is one solution I hadn't thought of (or anybody else, for that matter).

I can see no reason it shoulsn't work and has the added advantage of extreme simplicity.

Provided. of course, the bells haven't been wired with traditional bell wire which had no colour coded conductors for identification!

However, a simple meter check with the series bells temporarily powered by a battery should resolve that problem.