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Door bell problem

B

Brent

Jan 1, 1970
0
I posted about this in the thread "Need to mod door bell" on 12/20/03
and was given several things to do. But I'm having trouble deciding
which to do.
I was also asked to post more info or a schematic, which I did on
12/30 but didn't get any replies.


My problem:

While I was gone one day, my door bell button got stuck and since the
'ding' piston in the bell unit was stuck out (w/ current), it melted
the the plastic around it, so it doesn't work.
I just replaced the button < 2 years ago, with Broan button with nice
brass plate (not the cheapest they had). Yes, I can/will get another
button, but there's always a possibility it could happen again. It
seems like it could be a fire hazard too.

What the best or easiest mod can I do to keep the bell from melting
again if the button sticks?



transformer and wall box:
http://pics.apartment808.com/users/Inverted/db1.jpg
http://pics.apartment808.com/users/Inverted/db2.jpg
http://pics.apartment808.com/users/Inverted/db3.jpg

door bell unit:
http://pics.apartment808.com/users/Inverted/db4.jpg
http://pics.apartment808.com/users/Inverted/db5.jpg

button:
http://pics.apartment808.com/users/Inverted/db6.jpg

simple schematic I drew:
http://pics.apartment808.com/users/Inverted/db7.jpg
Sorry I couldnt get the text tool to work to label. Blue box is the
wall box (wires go to circuit breaker panel/door bell button), black
filled box is the transformer, black outlined box is the door bell
unit, gold wire is bare copper wire, light blue thing is where i
thought about adding a fuse.
 
H

happyhobit

Jan 1, 1970
0
Hi Brent,

Your schematic don't look right. You should have two wires from your
doorbell. (Your drawing only shows one)

One wire from the doorbell goes to the transformer secondary (screw
terminal) and the other wire goes to one of the pushbutton screw terminals.
A wire from the other pushbutton screw terminal goes to the other
transformer secondary terminal (screw terminal). The transformer primary
(120 VAC) looks correct.

I did a Google for "Doorbell circuit" and got,
http://home.howstuffworks.com/doorbell2.htm,
http://home.howstuffworks.com/doorbell3.htm and 128 others.

The secondary is not usually fused but it wouldn't hurt. If the secondary
was fused the fuse probably wouldn't have blown. You would probably smell
the plastic melting first. I doubt that there is a big danger of fire.

Jay
 
N

Neil

Jan 1, 1970
0
I disagree, I think that putting a low-amperage (try 500ma or 1 amp max
fuse) in series with the output of the transformer. If anything shorts, it
will probably blow the fuse before anything melts.
Try experimenting with different values of low amperage fuses, if you don't
know how to measure amperage.

Kim
 
B

Bill Bowden

Jan 1, 1970
0
Brent said:
I posted about this in the thread "Need to mod door bell" on 12/20/03
and was given several things to do. But I'm having trouble deciding
which to do.
I was also asked to post more info or a schematic, which I did on
12/30 but didn't get any replies.


My problem:

While I was gone one day, my door bell button got stuck and since the
'ding' piston in the bell unit was stuck out (w/ current), it melted
the the plastic around it, so it doesn't work.
I just replaced the button < 2 years ago, with Broan button with nice
brass plate (not the cheapest they had). Yes, I can/will get another
button, but there's always a possibility it could happen again. It
seems like it could be a fire hazard too.

What the best or easiest mod can I do to keep the bell from melting
again if the button sticks?

Well, you might add a resistor and LED light across the
button which will light when the button is open.
So, when you notice the light is out, it means the
button is stuck.

Another idea is to use a small relay across the button
so the relay opens when the button is pushed. The relay
could control a timer that shuts off power after some
period of time.

-Bill
 
H

happyhobit

Jan 1, 1970
0
Hi Kim,

If you're disagreeing with, 'If the secondary was fused the fuse probably
wouldn't have blown.' Then I'd point out that the pull in current for the
bell is higher than the maintaining current. So it won't blow if the
pushbutton sticks.

If it's the, 'I doubt that there is a big danger of fire.' Then I'd point
out that if there was a 'big danger' then someone would have come up with a
good solution it before now, maybe like making the coil with a fire
resistant plastic.

Adding a fuse won't hurt I just question the benefit.

Jay
 
B

Brent

Jan 1, 1970
0
Maybe the problem is that the one white 'wire' I show by itself on the
right side is actually two conductor wire. I drew it just like it is
to match the photos (did you look at them?). In the drawing you can
see where the outer sheilding ends and it 'splits' to two separate
conductors. One goes straight to bell, the other to the transformer
(then to the bell), just like the howstuffworks page.
Again, sorry I didnt label the items. Makes it harder to figure out
my drawing. I had to hurry and couldnt get PSP's text tool to work
(but have several times before). I may go back and try again.

Mine is wired like those in the links you gave, but I dont think those
or mine is wired like you describe. But it's late. I'll have to think
about it later.
 
H

happyhobit

Jan 1, 1970
0
I'm sorry Brent,

I did look at the photos but failed to see the two wires coming from the
twin-lead, my error

Selecting another color in your drawing for the twin-lead (gray or off
white) would make it easier to understand.

Now that I understand, your wiring looks correct and your proposed location
for the fuse should be fine.

Jay
 
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