On Saturday, 27 October 2018 17:20:21 UTC+1, Brian-Gaff wrote:
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

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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-stairs
transformer adjacent to the breaker panel, to the front door bell push via
an over the door bell
(https://www.screwfix.com/p/byron-120...ll-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
able 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
really 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
appears 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 sync
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
with 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 of
some use in such situations. But what type of capacitor and what value?
Anyone?

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
batteries.

Long read I know, so thanks for reading.

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

Hi Brian,

The (mechanical) bells are running on AC. I haven't tried them with DC yet. The relay is an AC relay. Parallel is not an option in this case. The switch / bell push is in series with the original bell on a single 2 core bell wire and I don't have the option to run a new wire to the switch.