Multiple doorbells - need a bigger transformer!

[JohnW2]

#2 doesn't look competent - cables in notches like that.

Tell that to my house

Kind Regards, John.

 

[Stoday]

Having been in hospital recently, all I can say is beware females wearing gloves...

 

[JohnW2]

Having been in hospital recently, all I can say is beware females wearing gloves...

That's a bit sexist - males in hospital wearing gloves can be just as worrying, if not more

Kind Regards, John.

 

[Taylortwocities]

The first one, I think - not so much for the 'obvious' reasons but, rather, because without additional data, I don't think I would be certain that the second one is female!

#2 doesn't look competent - cables in notches like that.

Still - she's obviously expecting to meet you, John - the gloves, goggles and hard hat are in case you come across her, you filthy brute.

Well, there you go. #2 is Rebecca. That picture came from some stuff that JTL / Amicus pushed out a year or two ago.
Here's another from JTL's current website.

Untitled

• Taylortwocities
• 4 Sep 2011
• 2

Must have lost her screwdriver. Good, innit?

 

[sparkybird]

To get back to the point guys.....

I emailed Friedland yesterday (Sun) and came home to find a reply already

"Thank you for your enquiry.

It is possible to get 3-4x D792 (under dome bells) running from one transformer.
We would recommend 12V 2A transformer which will be more then enough on 30m run.

For further advice please call our helpline below."

I've emailed back to ask for confirmation of current draw for each bell as it must be around 0.25A

SB

 

[JohnW2]

I emailed Friedland yesterday (Sun) and came home to find a reply already
"It is possible to get 3-4x D792 (under dome bells) running from one transformer. We would recommend 12V 2A transformer which will be more then enough on 30m run."

Glad you got such a rapid response, and one which more-or-less corresponds to what I suggested early on!

I I've emailed back to ask for confirmation of current draw for each bell as it must be around 0.25A

Yes, as I said, it must be below 0.5A, and probably quite a lot less than that. It also makes sense if one does the sums....
I think 'bell wire' is usually 1/0.5mm, sometimes 1/0.6mm or 7/0.2mm. That corresponds to CSAs of around 0.2, 0.28 & 0.22 mm² respectively, hence voltage drops (total of both conductors) of roughly 224, 156 & 200 mV/A/m respectively, hence voltage drops for 0.25A over 30m of about 1.68V, 1.16V & 1.5V respectively - i.e. with a 12V supply, voltages of about 10.32V, 10.84V & 10.5V respectively reaching the bell - which certainly should be fine.

Kind Regards, John

 

[sparkybird]

Thanks John for confirming that. I do feel like I've gone round in a big circle with this one, BUT thanks to everyone on here, I fell like I've gained some new knowledge

Cheers

SB

 

[mattylad]

Depends what you're actually replying to, but 7812s aren't fond of a.c.

Add a bridge, cap et all too of course.

 

[JohnW2]

Depends what you're actually replying to, but 7812s aren't fond of a.c.

Add a bridge, cap et all too of course.

The problem with your idea is that the high current (hence potentially high voltage drop) loads were were discussing are bells which need AC to work. Your idea would give them a nice regulated DC voltage, but they wouldn't work

Kind Regards, John.

 

[mattylad]

Sorry, missed that bit... lol.