I just bought an Nutone IK-25 door
intercom. However, the documentation is
pretty bad. I actually wanted a
schematic of the master unit, but Nutone
says they don't even have it as the
product is purchased as-is. I don't
really believe this, but I guess it
could be true. BTW, this unit is not
even carried by Nutone anymore. Does
anyone know of a schematic for this
unit? Thanks.

Well, years ago and far away, I worked with some NuTone intercoms.
Those were vacuum tube units at that time (I *SAID* long ago...).
Basic idea was to use the loudspeaker as both a 'speaker, and as a
microphone. The switching (controlled from the central unit) simply
swapped the input/output. The remote unit was three wires -- ground,
audio in/out, and push button to ground for an alarm at the master
unit. Control panel on the master has a set of lights and alarm
buzzer. User on remote would request access/etc. Master would select
the proper remote and talk. Can't believe the new ones would differ a
lot from that basic design, other than going to solid state. Real
simple, and dead bang reliable. New ones probably have more features,
but that is the basic design.

On 9/30/2010 3:04 PM, deadgoose wrote:
Well, years ago and far away, I worked with some NuTone intercoms.
Those were vacuum tube units at that time (I *SAID* long ago...).
Basic idea was to use the loudspeaker as both a 'speaker, and as a
microphone. The switching (controlled from the central unit) simply
swapped the input/output. The remote unit was three wires -- ground,
audio in/out, and push button to ground for an alarm at the master
unit. Control panel on the master has a set of lights and alarm
buzzer. User on remote would request access/etc. Master would select
the proper remote and talk. Can't believe the new ones would differ a
lot from that basic design, other than going to solid state. Real
simple, and dead bang reliable. New ones probably have more features,
but that is the basic design.
Yes, I actually designed and built, and
re-designed and rebuilt the intercom in
my last home. Here I needed something
simpler so I bought the IK-25 which was
perfect for my application. This unit
has only 2 inside stations and one (or
2, optionally) door stations (I only
need 1). The 2 inside stations can talk
to each other, but each has to hit the
talk button in order to talk. The door
station doesn't require the person at
the door to push anything, other than to
ring the doorbell. I would like
communication between the 2 inside
stations to work that way also. I
don't need or want a "private" intercom.
My previous intercom had 6 inside
stations and all were "non-private" so
you could listen in on any station. You
could tell if the system was on because
there was an LED on each unit ... so if
the LED was on, someone may be
listening. This never caused a problem,
even with 2 kids. I could have built
this intercom, but I am building many
other things in the new home, and I
wanted this to be a simple install. I
guess I'll have to make a schematic from
looking at the PC board and wiring,
unless someone comes up with a schematic.

On Oct 1, 8:01*am, Art Todesco wrote:
On 9/30/2010 3:04 PM, deadgoose wrote: Well, years ago and far away, I worked with some NuTone intercoms.
Those were vacuum tube units at that time (I *SAID* long ago...).
Basic idea was to use the loudspeaker as both a 'speaker, and as a
microphone. The switching (controlled from the central unit) simply
swapped the input/output. The remote unit was three wires -- ground,
audio in/out, and push button to ground for an alarm at the master
unit. Control panel on the master has a set of lights and alarm
buzzer. User on remote would request access/etc. Master would select
the proper remote and talk. Can't believe the new ones would differ a
lot from that basic design, other than going to solid state. Real
simple, and dead bang reliable. New ones probably have more features,
but that is the basic design.

Yes, I actually designed and built, and
re-designed and rebuilt the intercom in
my last home. *Here I needed something
simpler so I bought the IK-25 which was
perfect for my application. *This unit
has only 2 inside stations and one (or
2, optionally) door stations (I only
need 1). *The 2 inside stations can talk
to each other, but each has to hit the
talk button in order to talk. *The door
station doesn't require the person at
the door to push anything, other than to
ring the doorbell. *I would like
communication between the 2 inside
stations to work that *way also. *I
don't need or want a "private" intercom.
* My previous intercom had 6 inside
stations and all were "non-private" so
you could listen in on any station. *You
could tell if the system was on because
there was an LED on each unit ... so if
the LED was on, someone may be
listening. *This never caused a problem,
even with 2 kids. *I could have built
this intercom, but I am building many
other things in the new home, and I
wanted this to be a simple install. *I
guess I'll have to make a schematic from
looking at the PC board and wiring,
unless someone comes up with a schematic.

Art:

Try posting on sci.electronics.repair

Bob Hofmann

On 10/2/2010 10:59 AM, hr(bob)
wrote:

Art:

Try posting on sci.electronics.repair

Bob Hofmann

Bob,
Good point, I'll try that.