Doorbell push indication?

Not good for battery life even with a high effciency LED. It also only indicates that the switch contacts made not that the ding-dong ding-donged. Especially with an high effciency LED that'll light quite brightly on only a mA or so.

<snip>

It might have been ... depending on how I would wire it up?

Assuming it's the same model, would the idea be that the first unit powers the second and both operate when you press the button?

Wouldn't they have to be in series to do that (one without the battery circuit) and then they would both be working on half the voltage (unless I replace the battery with a 12V one)?

If both were powered and commoned at the same bell push, wouldn't there be the need for diodes on both 'lives' to the bell push so that they didn't leak voltage back to each other (that would be fairly doable).

Or have I miss something more obvious?

I guess a small relay (coil) in series with the first and actuating the second could also work?

Cheers, T i m

Ding-dongs (which don't have an interrupter contact) should be able to be run in series as long as the bell voltages add up to the power supply voltage.

As long as you replace all the batteries at the same time, two similar ding-dongs with batteries in each would equal 8 cells in series with 2 chimes.

Trembler bells of similar type can be run in series provided that only one has interrupter contacts, which act for all the bells. The interrupter on all the other bells needs to be shorted.

Owain

That implies 12V being available rather than the usual 6V.

Why not have a second Ding-Dong style bell by the front door and have both in series? Preferably the same make/model so same load. If it's unbalanced then add a modest 6V zener (or resistor) across the bell taking up the volts.

Um no.

Two battery doorbells, wired ?in parallel? to the same bell push.

Don?t see why they should need that. They?ll both be open circuit until the push is pressed.

I think you?re over-complicating things.

Tim+

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Ok ...

Yeah, I got that, but then both *batteries* would also be in parallel, via the solenoid coils? Ok as long as they were the same make / model / condition *and* wired the same way round (+/- etc).

Yeees, but they would both be in parallel battery wise, unless you had a dual pole doorbell switch?

See above. ;-)

Cheers, T i m

Understood.

Check.

Noted (this isn't such).

Alternatively, I could rewire one unit to be just the bell (takes me back to my BT and 706 days <g>) and replace the batteries in the main unit with 3 x 18650's. ;-)

Cheers, T i m

That wasn't part of the original ideal but wouldn't be too difficult to arrange etc (easier than running additional wires between door and bell or running power to the main bell etc).

If I was to up the voltage on the main unit (3 x 18650's (and a small BMS), nominally 12V) I could have a zener in series with the push button and your idea of a buzzer across it? 3D print a couple of dummy battery tubes and I could probably make it all plug and play (albeit swerving the original plan a bit, but without having to mess with the wiring or design anything)?

I think that would have the smallest component count (ignoring the battery bit that would be easy), potentially the most predictable results and the (white) buzzer right behind the bell push where they would most likely hear it?

Cheers, T i m

Assumed doorbell circuit. Arrows go to extension circuit.

<------+------- solenoid -------+ | | + \ x ----- 6V \ --- x | - | | <------+------------------------+ +-------------< | RLED (6-2)V / 10mA = 390 ohms 1/8th watt | or larger +-----+ Limits current while LED runs. + | | Limits charging current too though. ----- --- Use two resistors, one per diode, to adjust this. 1N4001 \ / ^ v / \ LED Yellow 2.0V LED --- ----- | | + +-----+ + | --- 2200uF (salt to taste, RLED*C tau) --- C | +-------------<

If the cap isn't recharging fast enough for taste (LED doesn't work when nervous nelly does a drum solo on the button)... This will allow the cap to recover between staccato button presses, a little bit. The lower limit on resistor value, is 1N4001 current rating, and you can use a larger diode if desired. I just happen to have a pack of 1n400x sitting around, so it's the first number that comes to mind. They're pretty cheap if not bought at Radio Shack.

+-------------< | 6.2 RCAP Limits diode current flow, use larger diode if desired... Ohms | Recharges cap for next pulse, more quickly. +-----+ | | | RLED (6-2)V / 10mA = 390 ohms 1/8th watt | | or larger | | Limits current while LED runs. + | | ----- --- Diode prevents >5V from appearing 1N4001 \ / ^ across the reversed yellow LED. Only v / \ LED Yellow 2V indicator LEDs allow a PIV like this. --- ----- Power LEDs are less tolerant on PIV. | | + +-----+ + | --- 2200uF (salt to taste, RLED*C tau) --- C Grab any old cap from the electrolytics box, and test :-) | You'll be breadboarding this circuit before buildup. +-------------< to get the aesthetics right.

If you make the RLED a lower value, like say 220 ohm, to get more current through the LED, then the cap value rises to give the same time constant as before.

If you use back-to-back LEDs, then the button release gets a bit of color too. You want LEDs with similar Vf, so that the current flow levels aren't too much different during charge/discharge of the cap. Yellow and red would be good. Throwing blue into the circuit less so (blue is used in white LEDs too). The cap will not charge quickly enough if you do this (you would be using the first circuit, not the second), so having two colors to show, means the quick-button-pressers that play a drum solo on the button, don't get good lighting on subsequent tries.

The Vf actually follows Plancks constant, so the forward voltage isn't as "arbitrary" as it looks here (table). Blue, which is up the higher energy end of the band, has the higher Vf. You would then predict infrared LEDs, would be a lot lower Vf, without having to look it up. If I was doing two colors, red and green or red and yellow might be decent mixes. Blue and infrared would be too far apart to share a single resistor value.

The only question then, is whether leakage in the switch, or leakage in the capacitor, could lead to the batteries discharging to nothing, one of the cells reverse bias, juice ends up in the battery bay, eats the contacts in the battery bay, and so on... You could make the capacitor out of a large number of ceramics, but maybe the leakage would still not be exactly zero. The "large" ceramics I bought on sale, they're a bit leaky.

And doorbell switches are *the worst* switches on earth. They really put the effort into making awful ones (no precious metals on the contacts).

Anyway, you can have fun playing with the concept and whip something up. If you don't like LEDs, you could substitute something else, subject to the available voltage and current. And also, whether reverse PIV (0.7V via the 1N4001) is OK or not. One of the reasons for me putting the 1N4001 in the circuit, was as a PIV protection feature, so the PIV (peak-inverse-volts) situation would not be quite as bad.

Paul

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Spot on.

Nice thinking Paul. The 'clever' thing about that (assuming they are looking for the LED etc) is that it could all be in / just behind the bell-push (that is on the uPVC door frame).

'Nervous Nelly' <weg>

I'm not bothered about that / them Paul. TBF, most people generally either press it once 'normally' (press - release) or go for the 'I'll ring it longer' but then I just get the 'Ding ............. dong'. ;-)

I might have to be careful that too small a resistor causes the solenoid to hang or not allow the 'dong' if it doesn't release cleanly as it's re-charging the cap?

I have a roll of them as well. ;-)

Quite! Buying two diodes from RS was normally the same price as 100 at my local electronics suppliers (all now long gone though). ;-(

OK.

Noted.

Noted.

I don't think the switch would leak at all (unless it was wet)so it would be down to the cap.

I think it would all be a trade off between functionality (both electronically and in RW outcome)and 'increased burden' on the system / batteries etc.

Agreed, certainly in refinement but then maybe they need to be like that if they get wet / dirty?

;-)

Thanks ... and thanks very much for all your effort re diagrams and explanations etc. You are very kind. ;-)

I like relays and you can get some fairly small ones these days. They are pretty durable and generally last for a fair few operations, especially if driven and rated correctly.

I think I agree with some of the other replies suggesting an audio confirmation might be more of a 'catch all' solution, re a small mechanical buzzer mounted behind the bell-push on the inside of the door frame. If I could get some charge in a cap to act as a remote PSU and use your idea (probably with a second cap) to activate a small relay that then self latches, powering the buzzer from the PSU cap?

I'd need to draw it out to see if / how it might work.

I will try the LED solution on the bench though after measuring the current through the doorbell.

Yes, that was mentioned elsewhere etc. One advantage of the nasty / crude bell-push is it's pretty resilient to such things. ;-)

Thanks again Paul.

Cheers, T i m

Yeah, this seems the simplest solution. Two bell units with batteries fitted in both everything series connected. The gotcha might be getting a second ding-dong unit that presents a similar load to the orginal but it's probably not that critical.

Could do but you have to faff about making a holder for the

18650's...

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Assuming they haven't changed the design in the last 30 years ... ;-)

Well, where it's fitted there is space behind (under the stairs) so it could just be a hole though the back and a pack kept there.

However, finding space to mount and run wire to a second unit isn't that easy, that's why I liked your mini mechanical buzzer idea (as that could be mounted behind the bell push on the frame itself).

So maybe I could do both, find a suitable mechanical type buzzer and up the voltage (giving more options on the buzzer), as at least that would be easy in that I don't have to work out how I got the wire from the bell to the push putton? ;-)

Cheers, T i m

the most obvious option is a sounder that can be heard at the door. If mounted close by, a piezo one would do. Change its operating f so it's neither annoying nor overly loud.

NT

You need to design and make a miniature dingdong mounted near the door, dropping only 1V in series with the existing push. It only has to be loud enough to be heard there so not much power needed.

You need a dingdong rather than a buzzer to make the caller realise that keeping the button pressed is counter-productive.

I think the torrent of presses used by some callers is to make you think they're not chancers, so worthy of having the door opened.

My doorbell is entirely software, apart from the bell push. It has debouncing code, also a delay before it works again. I need to increase that.

It rings all the phones in the house (see previous posts) but I have the same problem that it's not audible outside. I have the parts for a 'repeater' but haven't located a tuit yet.

The plan is to play something through a glass mounted speaker over the door. I could vary this; two that seem good are Westminster chimes, and "Time" from Pink Floyd.

"Time" I like that idea... hum...

"Knocking on Heaven's door"

Get a midi file and play it with a chime voice.

Owain

The trouble with wireless and fancy electronic bells is that their response is always the same, giving no indication of how desperate the caller is.

Hmmm. Currently the bell push is connected to a digital input on an Arduino.

A different transducer, and the analogue input...