Nutone IK-25 Door Intercom schematic

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.
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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.
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On 9/30/2010 3:04 PM, deadgoose wrote:

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.
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Art:
Try posting on sci.electronics.repair
Bob Hofmann
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On 10/2/2010 10:59 AM, hr(bob) snipped-for-privacy@att.net wrote:

Bob, Good point, I'll try that.
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