Author Topic: Can two 500's be connected as a Manual Intercom System?  (Read 1654 times)

Offline trainman

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Can two 500's be connected as a Manual Intercom System?
« on: April 13, 2011, 02:49:23 AM »
Can one convert say 2 500 type phones to local battery with ringer boxes and use as a intercom system?
« Last Edit: February 15, 2016, 12:44:36 AM by AE_Collector »

Offline Owain

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Re: Can this be done
« Reply #1 on: April 13, 2011, 04:41:04 AM »
Yes, sort of.

See the second circuit here.

Offline dsk

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Re: Can this be done
« Reply #2 on: April 13, 2011, 05:33:04 AM »
Yes it can be done,
The circuit over is one example. If you use voltage of high enough, e.g. 18V (or more) you may bridge each telephone with a beeper in series with a zener-diode of a little higher voltage than half of the battery voltage.  When one telephone goes off hook the voltage drop is reduced, and the beeper will sound in the other end.

If you really want the high end local battery speech circuit, you have to get a low resistance/high impedance coil in series with e.g. 3V battery connected in parallel with the transmitter.  To get a hookswitch for turning on/off the battery power, you may use one of the hook-switch contacts for that and leave one of the lines in circuit all the time.
Then you have a circuit equal to the field telephone  TA43/pt.

dsk

I have even got a regular New York number :-) 646 570 1796

Offline m1898

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Re: Can this be done
« Reply #3 on: December 12, 2011, 02:48:42 PM »
I am using the diagram metioned in the second post for my model railroad. I will be using a seperate circuit for the call lights. They consist of flashing LEDs run by momentary contact pushbuttons. Note about the circuit diagram, the phone on the right has to be on that end by itself. The ones on the left may be all on the same pair of wires. I will power my phones with a 12volt jump pack, no resistor needed. If you need mode details, I will try to get a rough sketch for you.  Jim
"Oh lord it's hard to be humble, when you're perfect in every way. I can't wait to look in the mirror, I get better looking each day"

Offline GG

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Re: Can this be done
« Reply #4 on: December 13, 2011, 03:48:58 AM »


Would that be a model railroad layout that's so large it becomes necessary to talk over a phone circuit to manage the operation of the whole thing when it's all running?

I've seen pictures of layouts like that: museum-scale setups that manage to duplicate entire vast swaths of countryside and cityscape and everything in between.

For those who have never seen anything like this: envision building a duplicate of reality on a scale of 1/87 (think "Matchbox cars" though they aren't exact scale), and doing it so well that from photos you can't tell it's not real. 

I have high respect for people who can build stuff on a tiny scale like that, that's photographically realistic, whether it follows reality 100% or whether it depicts an entirely fictional world.   

Offline m1898

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Re: Can this be done
« Reply #5 on: December 13, 2011, 04:11:56 AM »
It's not. It is built in the larger bedroom (about the size of a one car garage) in our other house. The dispatcher's desk will be in the walk-in closet at one corner. He will have his back to everybody so he can't see what's going on. I don't need a phone system for dispatching, I just want one.
"Oh lord it's hard to be humble, when you're perfect in every way. I can't wait to look in the mirror, I get better looking each day"

Offline Bill

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Re: Can this be done
« Reply #6 on: December 13, 2011, 11:31:36 AM »
Would that be a model railroad layout that's so large it becomes necessary to talk over a phone circuit to manage the operation of the whole thing when it's all running?

I know this is off-topic, and I don't mean to hijack this thread (mod: move or delete at will), but your comment reminded me of something. Here in greater Phoenix there is a very active model railroad club. Several members specialize in G- (for Garden) scale trains, which are 1/22 scale. Big, in other words. Some of these members have, in the past, opened up their homes and yards to public tours around Christmas, and literally thousands of people attend. I hope they do it again this year.

Anyway, the biggest layout belongs to a guy named Dennis Sirrine. He has over 6000 feet of track, and the layout must cover a couple acres. Most of it is outdoors, of course, though several sidings run into a multi-car garage that serves as a train shed. It truly is large enough that it needs telephone communications among the operators.

He has posted several videos of his "toy trains". Here are links to a couple of them, and you can find more by doing a Youtube search on dennissirrine. If you are into this stuff, you might check them out.

The first one gives an idea of the scale of the thing by showing a couple dozen spectators.
http://www.youtube.com/watch?v=ZP6qZj1QnCU
The second gives a trains-eye view, showing layout, other trains, buildings, etc, complete with sound effects
http://www.youtube.com/watch?v=0VBW50ctHoY

All I can say is "Wow!"

Bill

Offline GG

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Re: Can this be done
« Reply #7 on: December 14, 2011, 09:09:39 AM »

Yeah, that scores definite major Cool points.  The original "virtual reality".  If you have the space to do that, it's better than just another boring lawn, and the amount of skill & effort that go into creating a layout like that are awesome. 

IMHO same case with folks in our corner of the world who've built working Strowger switches in their garages. 

BTW, we could have a functional national rail network by simply doing some cleanup of existing track and so on, without having to replace it all or build a special high speed network.  It could run at speeds between 80 - 125 miles per hour, and cover coast-to-coast runs in a couple of days easily.  Every other civilized country is ahead of us on this.  Here's to hoping that guy in Phoenix encourages his visitors to write letters to Congress to support funding for Amtrak.