I used to have a separate doorbell transformer. During some kitchen work the electrician fitted a new transformer inside the consumer unit. I can now hear a (50Hz)buzz in the bedroom above.
At the moment I am not fit enough to do any streching to try relocating it or trying to mechanically isolate it. I am wondering it an electronic voltage reduction device is available that could be smaller and not liable to vibrate. The door bell - is a load buzzer.
They are just a small regular transformer in a DIN-rail mounting case.
I made a switched mode one by transplaning a switched mode PSU from a wall wart to a DIN-rail case, but this was because I needed a regulated power supply.
You can buy DIN-rail mounting switched mode power supplies, but the price is through the roof.
DerbyBorn used his keyboard to write :
Most everyone moved over to modern wireless versions long ago, but best to get a good one Freidland EVO are a good and reliable one.
Just isolate the input to the transformer, likely its core will have worked loose.
The other good news is that they use electricity all the time. Whereas a battery operated doorbell only uses power when a finger is on the button.
harryagain presented the following explanation :
If you meant the wireless type, the bell unit uses a constant amount of current to keep its receiver working. The bell push only uses the battery when the button is pressed and it transmits.
An old and chattering transformer will use more current than one in good condition.
Dunno but transformers buzz as do ballasts etc running at 50 hz, so if you know the voltage and current needed for the device I'm sure a suitable switch mode module will be available, but don't then moan if all the radios in the house are prone to interference. Brian
"harryagain" wrote in news:leg1rj$dfg$ snipped-for-privacy@dont-email.me:
I wish I had stopped the electrician before he started rewiring it as part of a kitchen extension!
I have a Friedland DIN mounted one in my CU, and it doesn't make a noise (I tend to notice stray buzzes/hums/whines more than most people).
Which is why you wait outside those people's front-door like a muppet, never sure if they simply haven't heard you, or if the AAA battery in the wireless transmitter is flat ... again.
Until a couple of years ago, our doorbell was still being powered by a couple of orange HP2's! Can't complain about battery life. ;-)
Tim
So how much does 1kWh cost if you get it from AA cells?
Bill
Most small transformers consume a few watts, say 5? Given there are
8,700 hours a year that equates to 43.5kWHrs, which at 10p per unit would be roughly £4.35That pays for quite a few alkaline batteries at Poundland. Plus batteries don't "buzz" in the bedroom above.
1W would be nearer the mark for that size.
Ball park figure: 1W continuous is approx £1 per year.
Fredxxx wrote in news:legdgn$rde$ snipped-for-privacy@dont-email.me:
When we bought the house we wanted a Buzzer (AC) and an illuminated button. The house already had a transformer.
It is the replacement DIN rail that is the problem. I guess that a wireless one would be my choice now.
Where did that figure come from?
Batteries go flat. Usually at the most inconvenient time.
You could use a toroidal transformer. They don't buzz.
Wireless bells are for the lazy and feckless ;-)
At least with a good old-fashioned bell push fitted with a festoon bulb, even if the caller can't hear the bell, he/she knows that the laws of physics dictate that the few watts that were illuminating it before the button was pressed, must be now dissipated somewhere else.
My wired bell push is a big round convex brass thing with a ceramic button that says PRESS. It's been on my house for 35 years but I reckon it's not far off 100 years old.
In message , "Dave Plowman (News)" writes
As this is a DiY group, how about having 2 batteries, main and standby, with an auto change over circuit that gives an indication when it has operated so that you have a couple of years warning that you need to change the flat battery?
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Many years ago, after we moved into the current dwelling, I fitted a GPO trembler bell ('perk of the job' item) and used a couple of 8 x AA cell holders to make up a 24v battery pack hooked onto a screw in the door frame immediately below where the bell had been fitted using a spare oblong door bell push just the other side.
This worked just fine for about a decade or so before the alkaline cells started to leak, ruining the battery holder. Rather than waste time trying to clean up the battery holder and spend a small fortune on another 16 AA cells, I simply bought a pack of 3 Carbon Zinc PP3s from a local Pound Shop and soldered straps to turn the pack of PP3s into a 27v battery (nothing was wasted!) which I hung on the screw head used by the previous bulky "battery". The result looked a lot neater than the previous arrangement.
A few years ago, prior to the PP3 battery pack job, I'd bought myself one of those wireless door bells so that I could still be alerted when I had my upstairs office door closed and noisy equipment running/ music playing.
I mounted the wirless sender to the inside of the door frame and connected it to the existing wired door bell using a blocking diode and a zenner 'dropper' so that its internal 12v battery only got used whenever it was pressed to test the 'Office Bell'[1] (callers operating the wired bell push caused the 24v (now 27v) to power the sender as well as the bell).
I did the 27v PP3 battery replacement about a year or so back and it'll probably be good for another 2 or 3 years before I need to spend a pound on another 3x PP3 pack. I spend more on the 3 AA cells used by the wireless bell unit which seems to need a fresh set every 12 months or so (again, a set of four alkalines can be had in most pound shops).
The door bell case is the classic example of disposable battery power being an effective alternative to mains power (no PSU failure to worry about and the cost of battery replacement is on a par with or better than the cost of the parasitic load of a bell PSU).
Being primary cells, I get ample warning of imminent battery failure without the need for any fancy voltage monitoring circuitry.
[1] My office door bell enjoys (endures?) frequent testing by SWMBI whenever she comes back with a load of shopping.
Most I have seen run rather warm, so must be more than 1 W?
No-one seems inclined or able to answer this, so I will.
A decent quality alkaline AA battery will produce 2.75 watts for one hour.
1kWh of mains power costs about 10p. So 1 watt/hour of mains costs 0.01p. So 2.75 watt/hours of mains power costs 0.0275p.If an AA battery of reasonable quality can be had for 10p, that makes the power from it 363 times the price of mains power.
So so it doesn't matter how you obfuscate it, anyone using batteries without very good reason is daft.
Having said that, I have a confession. In my house there is a doorbell sounder powered by four AA cells. It is activated by an external IR beam. It is not powered from the mains because that would involve me in
5 minutes' work once every 40 years, whereas I seem happier doing the two minutes' work changing the batteries every verse end.It was ever thus. The indolence of the so-called working classes is such a problem to respectable society.
Bill
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