Newby - 6 volt trigger

Thread Starter

Cowombat

Joined Jan 12, 2012
6
Hi all, my first post. I am just about zero in electronics knowledge, so had trouble identifying the correct key words for a search in the forum. So please accept apology if I should have found the answer already posted!!

Situation. I moved into a two storey rental house, so can't punch holes in walls etc. The door bell is downstairs and I can't hear it upstairs. I want to put in an extension ringer.

The existing doorbell is part of a mains powered 25 year old Electron Home Comms system. There is:
(1) a push button switch at the front gate (50 meters away and I can't replace it, and I don't want a second switch installed there)
(2) stepdown transformer somewhere hidden behind the internal walls delivering 6 volts (I can't get to it, only have access to the 6 volt wires
(3) 6 volt Friedland brand chimes (accessible)

What I tried to do:
I purchased a wireless doorbell system. The remote button unit can be opened and the PCB is accessible. My idea was to connect it in parallel to the wires from the cable that runs from the existing switch. So when the existing switch is closed, both (1) the old Friedland chime will ring and (2) the circuit will close on my new switch, triggering the wireless bell.
Seemed like a good idea, until discovering I don't have access to the wire running from the original button.

What to do next?
Your help please! Is there a simple way (yes, I own a soldering iron) that I can take the 6v that goes to the old Friedland chime to trigger my new wireless switch? I.e. I just have to have a method to close the circuit on the new switch.
Or is there some better solution altogether?

Thanks!
 

wayneh

Joined Sep 9, 2010
16,399
How is the remote button powered - probably a small battery? It's possible you could power it from the chime ringer circuit. (You would "permanently" close the button switch). To pursue this approach, it would help a lot to know how much current the remote needs. Do you have a multimeter that can measure current in the ~100mA range? Put it in series with the remote's battery and see how much current the remote draws.

There are other solutions, but this might be the simplest.
 

Thread Starter

Cowombat

Joined Jan 12, 2012
6
Ah, I see your line of thinking. The battery in the remote switch is a small 12 volt item (VR-22). I don't have a multimeter, but can probably find a friend with one.
But maybe first I just take a lead from your idea, running 6 volts from the original circuit straight to the remote with its switch closed. Never know till I try it, might be sufficient to transmit.
 

wayneh

Joined Sep 9, 2010
16,399
Most likely it will. But make sure the 6v ringer supply is actually DC. Putting an electrolytic capacitor in parallel, like it's a battery, may also help protect the circuit from a noisy power source. Since it's meant to run off a battery, it may not have a lot of protection built-in.
 

MrChips

Joined Oct 2, 2009
21,890
We need to know a bit more about the Friedland chimes. Can you provide a model number?

Once we know that, you will purchase a small reed relay. The coil of the relay will be wired in parallel with the chime. When the door bell button is pressed, it will send power to the chime and the relay in parallel.

The contacts of the relay will be wired in parallel with your remote pushbutton. When the relay contacts close, the radio transmitter in the remote will be energized and will send a radio signal to your wireless which will be located in your apartment.
 

Thread Starter

Cowombat

Joined Jan 12, 2012
6
It is a Friedland 117. I found the wiring diagram at http://www.tlc-direct.co.uk/Technical/DataSheets/Friedland/117.pdf
My system is wired according to diagram 4(a)
I can see from it that I was wrong in my original guesstimate of the circuitry.
Because I don't have a multimeter, I'm not sure what DC voltage is coming from the transformer - but presumably in the range of 8-16v.
I look forward to your advice as to the correct relay to install.

We need to know a bit more about the Friedland chimes. Can you provide a model number?

Once we know that, you will purchase a small reed relay. The coil of the relay will be wired in parallel with the chime. When the door bell button is pressed, it will send power to the chime and the relay in parallel.

The contacts of the relay will be wired in parallel with your remote pushbutton. When the relay contacts close, the radio transmitter in the remote will be energized and will send a radio signal to your wireless which will be located in your apartment.
 

MrChips

Joined Oct 2, 2009
21,890
I don't know where you are located but I'm guessing in the UK.
If that is the case your AC mains is 240V and so I will guess that the transformer is putting out 16VAC. I would look for a 12VAC relay.
 

Thread Starter

Cowombat

Joined Jan 12, 2012
6
Australia actually, so still 240 v. Thanks for the advice... I'll go get one!

And definitely AC? Just wondering, given the alternative power source is DC batteries. Not doubting, just ignorant and wanting to be sure :)

I don't know where you are located but I'm guessing in the UK.
If that is the case your AC mains is 240V and so I will guess that the transformer is putting out 16VAC. I would look for a 12VAC relay.
 

MrChips

Joined Oct 2, 2009
21,890
I should have guessed so from your name and the time. UK would be in bed by now.
Why AC? I'm going by the data sheet you posted.

Here is the closest thing I can find in the Radio Spares catalog. I don't know where you source your components.

http://australia.rs-online.com/web/p/products/5085539/?searchTerm=508-5539&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B337D5B5C732D2F255C2E5D5C647B332C347D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D424552267573743D3530382D353533392677633D4E4F4E4526
 

Thread Starter

Cowombat

Joined Jan 12, 2012
6
Ah yes, my handle is a bit of a give away, eh? I've ordered the relay via the web. Getting harder to buy such stuff locally. An excellent retailer that was close by has rolled down the shutters...
Thanks again for your help!
 

MrChips

Joined Oct 2, 2009
21,890
There are two relays shown in the product sheet with different styles of contacts. Either relay will work.



The RED wires go to the relay coil. This is the same for both styles relays.
The BLUE wires connect to terminals 11 and 14 on the relay. These go to the contacts on the wireless door bell button in effect performing the same function as the button.
 
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