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General => Off-Topic => Topic started by: Cole D. on October 05, 2019, 08:06:35 AM



Title: Intercom systems
Post by: Cole D. on October 05, 2019, 08:06:35 AM
This was inspired by the clock thread. Does anyone have any funny stories about mishaps with the intercom system at school or remember what kinds they have. My elementary school had the intercom speakers with rectangular metal grilles in each classroom and one side had a speaker and the other was for the clock. The hallways had square speakers on the ceiling.

One time, something happened and at the front office, they accidentally played music through all the speakers for about 30 seconds. It was If you see my reflection by Fleetwood Mac. Then another time we were having a fall festival outside and they were playing music the whole time which was some cheesey song about slicing up the pumpkins to make jack-o-lanterns.

Also at my college, usually they play music outside at the main courtyard and outside the gym. But one time it was playing all through the main building. I don't know if it was on purpose, but I don't think so, because it only played for one day. It was playing a station call Lite FM.


Title: Re: Intercom systems
Post by: Ash on October 05, 2019, 10:07:53 AM
At most schools built here in the 80s and 90s (my elementary and high schools were), there is a PA speaker system wired through the building inside (wood box speakers on the wall) and outside (megaphone style loudspeakers), and a parallel system of electromechanical bells

The speaker system is used for announcements, chime of beginning and end of class (8 bit tunes played from a chip in a schedule system, that plays the bell automatically at set times), and at high school it was used also to play music from CD's over during the longest break of the day

The electromechanical bells are supposed to be some backup but i never seen them being used, and i dont know from where they are controlled (that they most probably are switched by a contactor in some electrical panel, but i dont know from where the control signal for this contactor comes)

In my days at Jr high school i had some fun with it :

I recorded the 8 bit chime sound on a Walkman from a speaker in an empty room, cleaned it up in Audacity and burned a CD, which consists of : Pop music of the day (early 00's) in the beginning, then silence beginning few minutes before the end of the break, then after an hour (timed to come 5 minutes before the real end of class hour) the chime. I slipped this CD into the player so it will be played next day during the break

At the beginning of the break, whoever came to switch the music on put the CD on play and went to the break. By the time of the end of the break the music was allready stopped (the CD was playing silence), so nobody came to stop the player. The class hour started and the CD was still playing. 5 minutes before the end of class (and beginning of a 5 minute break), the chime played from the CD and at this point the CD track ended and player stopped. Students went out of class, teachers might have been confused but assumed that its their watches that are running late. 5 minutes after that, the real chime (that supposed to be for the beginning of the break) played, so everyone came back into class for the next hour. Then 5 minutes after the beginning of class, the real chime (for the real end of break) played again, making everyone fly out of class again, until they were called back



Title: Re: Intercom systems
Post by: Roi_hartmann on October 05, 2019, 11:57:07 AM
I have such system in use at home for background music and doorbell. Saved it from being scrapped.

http://www.whitenightcape.com/kuv/audico.jpg (http://www.whitenightcape.com/kuv/audico.jpg)


Title: Re: Intercom systems
Post by: Mandolin Girl on October 05, 2019, 04:29:47 PM

@ Ash
At my school they just had bells linked in to a central clock, but it was in the last century  :D


Title: Re: Intercom systems
Post by: A2ZAlarms on November 05, 2019, 07:28:01 PM
At home in the barn/workshop I have a Bogen paging system that is hooked to a Northern Telecom meridian phone system. I can hook up my laptop or phone to the DAC that is connected to the system to play music. some of the speakers have died over time and have been replaced with old car speakers etc. it is a 70V system. you can pick up any nortel phone in the building and hit the page button, once you do that the music stops, the speakers play an 8 bit chime and you can talk. when you hang up the phone the music plays again. in the future I would like to hook it up to the fire alarm system for voice evac.

Also, if anyone wants wiring info or some extra nortel phones (just pay shipping, i have more then you could shake a stick at) let me know.


Title: Re: Intercom systems
Post by: GE101R on November 05, 2019, 07:56:52 PM
At home in the barn/workshop I have a Bogen paging system that is hooked to a Northern Telecom meridian phone system. I can hook up my laptop or phone to the DAC that is connected to the system to play music. some of the speakers have died over time and have been replaced with old car speakers etc. it is a 70V system. you can pick up any nortel phone in the building and hit the page button, once you do that the music stops, the speakers play an 8 bit chime and you can talk. when you hang up the phone the music plays again. in the future I would like to hook it up to the fire alarm system for voice evac.

Also, if anyone wants wiring info or some extra nortel phones (just pay shipping, i have more then you could shake a stick at) let me know.

What type Nortel?  Thanks....


Title: Re: Intercom systems
Post by: Cole D. on November 05, 2019, 08:39:58 PM
At the schools I went to, there were no mechanical bell. The intercom system itself played "Beeeeeeeep!" to mark when classes begin or end.

The speakers in the newer parts of the high school had "Bogen" name on them, but in the older parts, the clocks that were on the speakers had "Dukane".


Title: Re: Intercom systems
Post by: GE101R on November 05, 2019, 08:51:35 PM
At the schools I went to, there were no mechanical bell. The intercom system itself played "Beeeeeeeep!" to mark when classes begin or end.

The speakers in the newer parts of the high school had "Bogen" name on them, but in the older parts, the clocks that were on the speakers had "Dukane".
Our first grade school bell intercom was Ms. Williams who was about 6 ft tall, 110 lbs with a mean look on her face always and she used a real "bell" that she rang from those tall steps to get us to come in for class. Dang, that was a while ago.


Title: Re: Intercom systems
Post by: sol on November 05, 2019, 08:52:44 PM
Bogen and Dukane are two well known institutional intercom manufacturers. Nowadays, everything is computer based, including school bells. The same speakers are used for PA, for the bell and for two-way communication.

I never had experience with Bogen, but I find the Dukane school bell slightly irritating. It is a high pitched bell imitation. Furthermore, the duration of the beeps are not timed to the duration of the sound event. You get some kind of ding-ding-di. It stops in the middle of the last ding. It must be my musical ear...

At my place of work, we have a Telecor system. I quite like the bell sound : a low pitch, square wave, two tone signal. Doesn't pretend to be a bell which it is not. Very short, but unmistakable.

When I was in school, we had those loud 60Hz buzzers (from Edwards, I believe).


Title: Re: Intercom systems
Post by: A2ZAlarms on November 06, 2019, 08:04:22 AM
What type Nortel?  Thanks....
they are regular nortel meridian phones, they require a nortel PBX to operate. you can get  nortel switch for free to 100 dollars due to most companies switching to voice over IP. here are the phones I have (picture 1) and a PBX (picture 2)
you will need a 25 pair phone connector to connect the phones to PBX. it also helps to have a 66 block or Block block to connect phone lines.(picture 3)
(not my pictures.)


Title: Re: Intercom systems
Post by: joseph_125 on November 07, 2019, 11:53:26 AM
I remember the intercom system at my elementary school was pretty much original to the building (early 80s) and had a car cassette deck that was only used to play the national anthem in the morning before classes started. It handled the bell too but interestingly the indoor bell was electronic but the outdoor one was a mechanical bell. I believe the classroom speakers were all two way and had a call buttom on them while the ones in the hallway were standard 70v speakers. I don't think there were phones in the classrooms.

I have a TOA amp that was designed to be an intercom amp and has inputs for things like a mic, telephone and outputs for 70v speakers but I reused it as a amp to play music in the garage.


Title: Re: Intercom systems
Post by: Mandolin Girl on November 08, 2019, 11:30:27 AM
We have a door entry intercom, that is getting towards the end of its life now.
It's original to when my block of flats was built in 1979/80. I'll get some photos of it and put them up later.
There is nothing visible that indicates a manufacturer though.


Title: Re: Intercom systems
Post by: Mandolin Girl on November 10, 2019, 01:08:35 PM
As promised here are the photos:

The intercom handset (https://www.lighting-gallery.net/gallery/displayimage.php?album=4722&pos=2&pid=167252)

The controlling buttons (https://www.lighting-gallery.net/gallery/displayimage.php?album=4722&pos=0&pid=167254)

The entry buzzer panel (https://www.lighting-gallery.net/gallery/displayimage.php?album=4722&pos=1&pid=167253) for the block.


Title: Re: Intercom systems
Post by: nogden on November 13, 2019, 11:18:08 AM
A2ZAlarms, that looks like a Norstar key system. Quite different from a Meridian PBX (like an Option 11 or CS1000). Both are excellent systems; I work on both. Lot of fun to play with. The Norstar is pretty easy to program if you have the manual, but the Option 11 PBX has a steep learning curve. Once you crest that curve, though, you can make those PBXes do 'bout anything you want.

At the school where I work, we have two Bogen-based one-way PA systems and one Valcom-based one-way PA system. Intercom is accomplished through a ShoreTel IP PBX. No real intercom systems anymore, sadly. We had a Bogen intercom system and a Rauland intercom system. Both worked very well. Its a shame they're gone. For the class change "bell", I homebrewed a tone generator based on a 555 timer using miscellaneous components I found laying around on my workbench. It is triggered by a Lathem master clock.

Another school where I used to work was still using a Bogen intercom system since there wasn't really any reason to replace it. Don't remember the master clock, but it triggered physical bells.


Title: Re: Intercom systems
Post by: wide-lite 1000 on November 13, 2019, 09:51:23 PM
We have a door entry intercom, that is getting towards the end of its life now.
It's original to when my block of flats was built in 1979/80. I'll get some photos of it and put them up later.
There is nothing visible that indicates a manufacturer though.

I zoomed your photos and the handset says Urmet and the entry panel says Entrotec , both companies still exist.


Title: Re: Intercom systems
Post by: Mandolin Girl on November 14, 2019, 05:59:00 AM
Thanks Tim, my eyesight isn't as good as it could be.  :-*

Without my glasses I'm as blind as a bat.!!  :D


Title: Re: Intercom systems
Post by: sol on November 14, 2019, 06:11:48 AM
Around here, most apartment complex intercom systems are not hard wired to the individual units. It is basically a wall-mounted, speed-dial only speaker phone with a standard line in the telephone company's exchange. All units in the building are assigned a random number (different from the apartment number) and a list of names (surnames only, often) is posted by the intercom so visitors know how to call the wanted apartment. When a visitor keys in the person's intercom number, it places a regular telephone call to that unit's standard telephone. The intercom places a call just like any other telephone in the company's exchange. When the wanted party answers, the intercom listens for a specific DTMF tone. When the appropriate key is pressed on the apartment telephone, the intercom triggers a relay that temporarily bypasses the door access control system so the visitor can enter the building.

Very old buildings simply had a standard door bell in each unit and a series of buttons in the foyer. A separate run of wires was daisy-chained through every unit, each having a button in parallel connected to it. When your visitor rang your doorbell, you would hold down the button for several seconds, triggering an electric strike in the main door. The disadvantage of this system is no communication with the visitor prior to letting them in the building. Some people wanting to get in would ring a random doorbell in the hope that the occupants would release the door.


Title: Re: Intercom systems
Post by: Mandolin Girl on November 14, 2019, 06:17:02 AM
Very old buildings simply had a standard door bell in each unit and a series of buttons in the foyer. A separate run of wires was daisy-chained through every unit, each having a button in parallel connected to it. When your visitor rang your doorbell, you would hold down the button for several seconds, triggering an electric strike in the main door. The disadvantage of this system is no communication with the visitor prior to letting them in the building. Some people wanting to get in would ring a random doorbell in the hope that the occupants would release the door.
Our system might as well be like that, as it's very difficult to hear what is said. We do have the advantage of being right by the main door though. So we can open our own door and have a look to see who is there.


Title: Re: Intercom systems
Post by: wide-lite 1000 on November 14, 2019, 09:42:44 PM
Thanks Tim, my eyesight isn't as good as it could be.  :-*

Without my glasses I'm as blind as a bat.!!  :D

 Not a problem ! My eyesight isn't what it once was either !


Title: Re: Intercom systems
Post by: Lightingguy1994 on December 05, 2019, 10:14:05 PM
My old elementary school which i still live down the street from used the usual mechanical bells outside except for one area which had a horn speaker but it still made a buzz at the same time as the bells. The indoor speakers were the usual grey square metal ones and there was a wall phone in each classroom.

One time during a summer thunderstorm a lightning struck the school and fried the bells and the alarm system too. All the bells, speakers and alarm were ringing 6 hours straight. They had to come and shut the power off to the school to stop it and make repairs.

The lightning also blasted all the roofed balls off the roof. I remember finding a black sooty deflated basket ball on the ground when i went to check it out.


Title: Re: Intercom systems
Post by: Mandolin Girl on December 06, 2019, 10:10:23 AM
We have an expression over here that sums this up nicely:

OH CRAP.!! :D


Title: Re: Intercom systems
Post by: sox35 on December 06, 2019, 11:44:23 AM
We have an expression over here that sums this up nicely:

OH CRAP.!! :D

Or, as you'll often hear us say when something has gone horribly wrong for the umpteenth time that day, Oh Crap Yet Again, usually abbreviated to 'OCYA'  :o :D