From Newsgroup: sci.electronics.repair

In the course of some maintenance I decided to work on the
doorbell circuit of my house. Its ring seemed erratic, and
I thought maybe the button was failing. It's an old-style
AC system, but only about 12 volts, low compared to the 24
volts normal today. The house was built in 1957, so the
era of relays, vacuum tubes and synchronous motor timers.

While working on it (and trying unsucessfully to stuff a
lighted button in place of the orginal, smaller, unlighted
button) the lighted button stopped lighting. It had worked
when hooked up for a quick test, light and all.

Put back the old button, still nothing, no voltage at the
switch leads. The old switch seemed ok to an ohmmeter test.

This caused something of a panic, thinking I'd broken
one of the wires (buried in the wall) near the switch.
But, the wires felt intact. Looking at the chime box
revealed two red wires but no transformer and no hint
where the wires came from. I gave up, put it all back
together as I found it and starated searching for the
transformer. No luck in any accessible place, the
inaccessible places were days' work to get at. So,
I waited till the next day and tested the doorbell.

It rang perhaps four times and I stopped to make some
notes. When I returned, it wouldn't ring. Ten minutes
later, still nothing. An hour later, nothing. About
eight hours later I tested again, it rang twice and
I stopped, greatly relieved.

Can anybody hazard a guess as to what's going on?
Long ago it was a common child's prank to ring a
doorbell and leave, a nuisance this setup seems
to defeat very nicely after a few tries. How one
would do it in pre-electronic times is not obvious
without a fairly expensive collection of hardware.
That seems implausible, but not impossible.

Web searches come back flooded with hits on "smart"
doorbell issues, so that's not much help.

Apparently there's nothing to fix, but there is a puzzle
to be understood. If anybody's got an idea......

Thanks for reading!

bob prohaska

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

On Sun, 20 Jul 2025 00:11:58 -0000 (UTC), bp@www.zefox.net wrote:

In the course of some maintenance I decided to work on the
doorbell circuit of my house. Its ring seemed erratic, and
I thought maybe the button was failing. It's an old-style
AC system, but only about 12 volts, low compared to the 24
volts normal today. The house was built in 1957, so the
era of relays, vacuum tubes and synchronous motor timers.

Sounds like the doorbell in my parents house. Built in about 1954.
12VAC. No timer. Two lighted push buttons (front and back doors)
each with it's own chime solenoid.

While working on it (and trying unsucessfully to stuff a
lighted button in place of the orginal, smaller, unlighted
button) the lighted button stopped lighting. It had worked
when hooked up for a quick test, light and all.

With a DVM, check if power to the button is present. If so, is it AC
or DC? If there's no voltage, look for a broken wire.

Put back the old button, still nothing, no voltage at the
switch leads. The old switch seemed ok to an ohmmeter test.

OK, the button works. Now, check if there's anything on the wires
coming from the transformer.

This caused something of a panic, thinking I'd broken
one of the wires (buried in the wall) near the switch.

That would be my guess. This was a problem in my parents house and in
two ancient rentals I lived in over the years. What happened was the
solid copper wires had become corroded by years of rain. Oddly, that
also made the wires a little stiff and brittle. Move the wires and
they'll break at the nearest "crimp", which would be where the wires
were bent into a "ring" and held in place with a brass screw. The
break was usually at the base of the bend. The wire strippers, would
cut through the cloth insulation and "nick" the wire copper wire. A
little bending, and the wires would break.

But, the wires felt intact.

Felt? Do you have access to a borescope or endoscope, normally used
for visually inspecting in tight spaces? I have several and use them
quite often. Something like this:
<https://www.ebay.com/itm/406035071136>

Looking at the chime box
revealed two red wires but no transformer and no hint
where the wires came from.

Find a "fox and hound" type signal tracer. I also have several of
these (for AC power line and telco): <https://www.google.com/search?q=fox%20and%20hound%20signal%20tracer&udm=2> With practice, you can follow wires inside of wooden walls. Tracing
through stucco, concrete, dirt and lath and plaster are more
difficult. If you're lazy, you can throw something together with an
audio tone generator, a pickup loop, and an audio amplifier.

If you have money to burn, try one of these:
<https://walabot.com>
<https://walabot.com/collections/all>
See #5 "How to detect and trace wires" <https://walabot.com/pages/whats-the-drill>

I gave up, put it all back
together

You give up too easily.

as I found it and starated searching for the
transformer. No luck in any accessible place, the
inaccessible places were days' work to get at. So,
I waited till the next day and tested the doorbell.

It rang perhaps four times and I stopped to make some
notes. When I returned, it wouldn't ring. Ten minutes
later, still nothing. An hour later, nothing. About
eight hours later I tested again, it rang twice and
I stopped, greatly relieved.

My intuition suggests a crude DC power supply either with a very old
capacitor or a wire that's getting hot with increased use.

Good luck.

Can anybody hazard a guess as to what's going on?
Long ago it was a common child's prank to ring a
doorbell and leave, a nuisance this setup seems
to defeat very nicely after a few tries. How one
would do it in pre-electronic times is not obvious
without a fairly expensive collection of hardware.
That seems implausible, but not impossible.

Web searches come back flooded with hits on "smart"
doorbell issues, so that's not much help.

Apparently there's nothing to fix, but there is a puzzle
to be understood. If anybody's got an idea......

Thanks for reading!

bob prohaska

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

On 20/07/2025 01:11, bp@www.zefox.net wrote:

In the course of some maintenance I decided to work on the
doorbell circuit of my house. Its ring seemed erratic, and
I thought maybe the button was failing. It's an old-style
AC system, but only about 12 volts, low compared to the 24
volts normal today. The house was built in 1957, so the
era of relays, vacuum tubes and synchronous motor timers.

How do you know it's a 12V AC system if you can't find the transformer?
Had you checked the voltage some time previously, or had the doorbell
failed to work when the AC power had been cut off for some reason? In a previous house we owned there was a door chime run by four "C" cells
inside the chime unit. They were there when we moved in and were still
working when we left 12 years later! In the new (but older) house I
replaced the wired bell which was unreliable as the wire had broken just inside the wall. The wireless bell is much better.

What's inside the chime box you mention below?

While working on it (and trying unsucessfully to stuff a
lighted button in place of the orginal, smaller, unlighted
button) the lighted button stopped lighting. It had worked
when hooked up for a quick test, light and all.

Did you use a 12V AC source for the test?

Put back the old button, still nothing, no voltage at the
switch leads. The old switch seemed ok to an ohmmeter test.

Switch? Did you mean the bellpush contacts?

This caused something of a panic, thinking I'd broken
one of the wires (buried in the wall) near the switch.
But, the wires felt intact. Looking at the chime box
revealed two red wires but no transformer and no hint
where the wires came from. I gave up, put it all back
together as I found it and starated searching for the
transformer. No luck in any accessible place, the
inaccessible places were days' work to get at. So,
I waited till the next day and tested the doorbell.

It rang perhaps four times and I stopped to make some
notes. When I returned, it wouldn't ring. Ten minutes
later, still nothing. An hour later, nothing. About
eight hours later I tested again, it rang twice and
I stopped, greatly relieved.

What voltage do you see across the red wires when tested "as is", and
when the bellpush button is pushed?

What happens when you short the bellpush leads with, eg croc clips,
rather than use the button? Does the bell ring consistently every time,
or is it still intermittent? If it works, try cleaning the bellpush
contacts and see if that helps.

Can anybody hazard a guess as to what's going on?

Not really...
--
Jeff
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

On 7/19/2025 8:11 PM, bp@www.zefox.net wrote:

It rang perhaps four times and I stopped to make some
notes. When I returned, it wouldn't ring. Ten minutes
later, still nothing. An hour later, nothing. About
eight hours later I tested again, it rang twice and
I stopped, greatly relieved.

Can anybody hazard a guess as to what's going on?

Not likely, not without tracing wires and finding that transformer. In
our last house, someone had wired the front and back door bell to the
same chime. I fiddled with the system for hours, until I finally got
the rear door bell to "ding-dong". The front doorbell button (same
chime) would only "dong". You know what, that was close enough for me!
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

On 2025-07-20 02:11, bp@www.zefox.net wrote:

In the course of some maintenance I decided to work on the
doorbell circuit of my house. Its ring seemed erratic, and
I thought maybe the button was failing. It's an old-style
AC system, but only about 12 volts, low compared to the 24
volts normal today. The house was built in 1957, so the
era of relays, vacuum tubes and synchronous motor timers.

What country? System differs by country.

Here (Spain) the doorbell is often on mains voltage (230Vac). Mine
stopped working few years back. I decided not to try to repair it,
because some of the wires are directly embedded in the plaster or mortar
and brick wall work outside, instead of the more modern method of
embedding plastic tubing.

So I bought a wireless system. The button outside has its own battery;
the internal bell is powered by mains. The interconnect via radio.

My neighbour had done the same thing years before me.
--
Cheers, Carlos.
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

On 7/22/2025 1:13 PM, Michael Trew wrote:

On 7/19/2025 8:11 PM, bp@www.zefox.net wrote:

It rang perhaps four times and I stopped to make some
notes. When I returned, it wouldn't ring. Ten minutes
later, still nothing. An hour later, nothing. About
eight hours later I tested again, it rang twice and
I stopped, greatly relieved.

Can anybody hazard a guess as to what's going on?

Not likely, not without tracing wires and finding that transformer.-a In
our last house, someone had wired the front and back door bell to the
same chime.-a I fiddled with the system for hours, until I finally got
the rear door bell to "ding-dong".-a The front doorbell button (same
chime) would only "dong".-a You know what, that was close enough for me!

Often doorbells can "ding-dong" or just "dong", depending
on how you connect the two wires at the bell, like this:

outside terminal {O} middle terminal {O} outside terminal {O}

One outside terminal is "ding-dong", the middle terminal is common
and other outside terminal is "dong" only. All you need to do is
move the outside wire to the opposite outside terminal, assuming
your bell is like that (and working).

Ed
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

On 7/19/2025 8:11 PM, bp@www.zefox.net wrote:

In the course of some maintenance I decided to work on the
doorbell circuit of my house. Its ring seemed erratic, and
I thought maybe the button was failing. It's an old-style
AC system, but only about 12 volts, low compared to the 24
volts normal today. The house was built in 1957, so the
era of relays, vacuum tubes and synchronous motor timers.

While working on it (and trying unsucessfully to stuff a
lighted button in place of the orginal, smaller, unlighted
button) the lighted button stopped lighting. It had worked
when hooked up for a quick test, light and all.

Put back the old button, still nothing, no voltage at the
switch leads. The old switch seemed ok to an ohmmeter test.

This caused something of a panic, thinking I'd broken
one of the wires (buried in the wall) near the switch.
But, the wires felt intact. Looking at the chime box
revealed two red wires but no transformer and no hint
where the wires came from. I gave up, put it all back
together as I found it and starated searching for the
transformer. No luck in any accessible place, the
inaccessible places were days' work to get at. So,
I waited till the next day and tested the doorbell.

It rang perhaps four times and I stopped to make some
notes. When I returned, it wouldn't ring. Ten minutes
later, still nothing. An hour later, nothing. About
eight hours later I tested again, it rang twice and
I stopped, greatly relieved.

Can anybody hazard a guess as to what's going on?
Long ago it was a common child's prank to ring a
doorbell and leave, a nuisance this setup seems
to defeat very nicely after a few tries. How one
would do it in pre-electronic times is not obvious
without a fairly expensive collection of hardware.
That seems implausible, but not impossible.

Web searches come back flooded with hits on "smart"
doorbell issues, so that's not much help.

Apparently there's nothing to fix, but there is a puzzle
to be understood. If anybody's got an idea......

Thanks for reading!

bob prohaska

Find the breaker (or fuse) at the panel that disables the
doorbell. That breaker *should be* labeled so that you know
what circuit it protects. If not labeled you'll have to
search to find what's not working. Your doorbell transformer
is somewhere on that circuit. The code requires that it is
accessible. Accessible means you do not need to remove any
permanent part of the building (e.g. wallboard) to get to it.
It may be hidden it behind storage boxes etc)
Likely places in general: at the breaker panel/near the
furnace/in the basement/the garage/attic and similar places.

Your description of the problem suggests the possibility
of an intermittent open in the transformer or the bell or
the wiring.

Ed
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

On Tue, 22 Jul 2025 13:13:14 -0400, Michael Trew
<michael.trew@att.net> wrote:

On 7/19/2025 8:11 PM, bp@www.zefox.net wrote:

It rang perhaps four times and I stopped to make some
notes. When I returned, it wouldn't ring. Ten minutes
later, still nothing. An hour later, nothing. About
eight hours later I tested again, it rang twice and
I stopped, greatly relieved.

Can anybody hazard a guess as to what's going on?

Not likely, not without tracing wires and finding that transformer. In
our last house, someone had wired the front and back door bell to the
same chime. I fiddled with the system for hours, until I finally got
the rear door bell to "ding-dong". The front doorbell button (same
chime) would only "dong". You know what, that was close enough for me!

Finding a doorbell transformer in a wall or ceiling is fairly easy.
The typical 18 or 24VAC transformer isn't very well shielded. <https://www.google.com/search?q=doorbell%20transformer&udm=2>
To find it, beg, buy, borrow or steal a non-contact voltage detector,
like one of these: <https://www.google.com/search?q=non%20contact%20voltage%20detector&udm=2>
Wave it around some likely locations until you find a very strong
50/60 Hz field. For situations where the non-contact voltage detector
is too sensitive, I use a large coil of wire and an auto amplifier
instead of the non-contact voltage detector. Extra credit for tuning
the coil to 60 Hz.
--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
--- Synchronet 3.21a-Linux NewsLink 1.2