Author Topic: Telephone System for a Model Railroad  (Read 1292 times)

Offline steveb919

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Telephone System for a Model Railroad
« on: April 15, 2013, 01:50:11 AM »
I have a large model railroad.  Once a month my friends and I "play trains" like the real ones.  I am modeling a railroad in the 1920 era.  I have installed a 9 telephone party line using a power supply, handsets, and cup hooks with contacts.  I have installed LEDs on all the cup hooks so when someone goes off hook the LEDs on all the phones light up.  I believe the handsets are type G with R/B/W/W wires.  I have a power supply with a relay.  When someone goes off hook, the relay clicks.  There is no phone dial or ringer.

At the dispatcher's desk in a separate room, I have a modern Plantronics S11 headset which plugs into a Plantronics box (I believe the box is an amplifier).  Going out from the Plantronics box is a plug with R/Y/G/B wires.  This plug is designed to go into a telephone set so one can talk hands free.  Here is my problem.  If I tie together the Y/B wires and have the R/G wires go to the two power supply wires, the dispatcher can receive calls but cannot transmit.  I have a 425 network board and I need to know how to hook up the power supply and the R/Y/G/B wires so I can receive and transmit with the Plantronics head set and mic.  I am not a telephone expert so my model railroader friends helped set up the party line.  Unfortunately they are unfamiliar with the Plantronics headset/amplifier so they are not able to help with hooking up the headset so it can transmit.  Is there a solution to my problem?

Thank you in advance for any advice/help,
Steve

Offline twocvbloke

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Re: Telephone System for a Model Railroad
« Reply #1 on: April 15, 2013, 03:06:08 AM »
I think the easiest option would be to use a Panasonic KX-T616 phone system, this would give you 16 intercom lines (US numbering is 11-to-26) between your phones, using a standard system phone, such as the KX-T7130, with your Plantronics headset on Ext.11, giving you the one handsfree phone and the rest can be any phone you like... :)

I will say though, the standard wiring on a modular RJ10 hand/headset plug is the outer pair is the Transmitter and the inner pair the Receiver, and ordered as Y-G-R-B (or vice versa depending on which end of the cable you look at), so joining the Y & B you'll have shorted out the transmitter meaning no speech transmission... :)

Connecting them to a 425-type network is relatively simple, the receiver pair (Green and Red) goes to terminals GN and R, the Transmitter pair (Black and Yellow) to B and R, for no-dial function connect F and RR together. The hookswitch, if using one, on the other hand, I'll let someone else advise on that cos I'm not sure about it myself!! :D

The other handsets with R-B-W-W wires are basically just Red & Black are the Transmitter and the two Whites are the Receiver... :)

Offline ESalter

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Re: Telephone System for a Model Railroad
« Reply #2 on: April 15, 2013, 08:48:27 AM »
I don't think a PBX type system is what he's going for.  I anticipate having a layout someday nad have given thought to what he's trying to do.  I've been saving WE G5(talkbar) handsets and hookswitches from scrapped out 554s.  I plan to make little boxes to mount the hookswitches in that also have a small speaker.  When you pick up the handset it switches from the speaker to the receiver in the handset.  The point would be to simulate radio as best we can.

---Eric

Offline steveb919

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Re: Telephone System for a Model Railroad
« Reply #3 on: April 15, 2013, 10:33:08 AM »
Eric is correct.  I don't want to use modern day telephones around the railroad.  I am just missing that small technical piece that will allow the dispatcher to talk to the other old style handsets.  The dispatcher never starts a conversation.  The engineer/conductor lifts the old style headset and starts the conversation.  Currently the dispatcher hears the start of the conversation but cannot transmit "train orders" because he cannot transmit through the mic on his Plantronics headset.  I will try hooking up the hooking up the Y-G-R-B wires to the 426 board and see how far that gets me.  There is no hookswitch that I'm aware of on the Plantronics setup.

Steve

Offline rdelius

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Re: Telephone System for a Model Railroad
« Reply #4 on: April 15, 2013, 01:05:39 PM »
One other thing you might need to watch out for. Add a inductor in series  with the power supply.this helps things with intercom circuits to keep the impedance higher and not loading the power supply

Offline steveb919

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Re: Telephone System for a Model Railroad
« Reply #5 on: April 15, 2013, 03:17:10 PM »
Put an inductor in series with the power supply?  Does that mean one end is attached to a power supply wire and the other to a 425 board terminal?  I have a 150 micro henry one.  Would that work?

Steve

Offline steveb919

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Re: Telephone System for a Model Railroad
« Reply #6 on: April 15, 2013, 03:23:51 PM »
I wired up the 425 board as mentioned below.  Still not able to transmit through the mic on the headset.  Also once I go off hook on the older handsets, once I hang up the handset, the LED does not go off which means the relay on the power supply is not being activated (or deactivated). 

Steve

Connecting them to a 425-type network is relatively simple, the receiver pair (Green and Red) goes to terminals GN and R, the Transmitter pair (Black and Yellow) to B and R, for no-dial function connect F and RR together. The hookswitch, if using one, on the other hand, I'll let someone else advise on that cos I'm not sure about it myself!! :D

The other handsets with R-B-W-W wires are basically just Red & Black are the Transmitter and the two Whites are the Receiver... :)
[/quote]

Offline Owain

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Re: Telephone System for a Model Railroad
« Reply #7 on: April 15, 2013, 05:20:59 PM »
Does this plantronics amp work when plugged into a phone on a phone line?


Offline steveb919

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Re: Telephone System for a Model Railroad
« Reply #8 on: April 15, 2013, 05:48:12 PM »
Does this plantronics amp work when plugged into a phone on a phone line?

Yes.  That was one of the first tests I made.

Steve
« Last Edit: April 15, 2013, 06:58:07 PM by AE_Collector »

Offline Owain

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Re: Telephone System for a Model Railroad
« Reply #9 on: April 15, 2013, 06:14:54 PM »
what power supply voltage are you using; what's the voltage present at the transmitters on your circuit compared to on the transmitters connected to a working phoneline?

A circuit diag. would be helpful.

Offline rdelius

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Re: Telephone System for a Model Railroad
« Reply #10 on: April 15, 2013, 07:48:40 PM »
if using networks or ind coils ignore using a series inductor. there should be enough.the intercoms I built had no networks and needed added induction to work.

Offline G-Man

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Re: Telephone System for a Model Railroad
« Reply #11 on: April 16, 2013, 03:21:19 AM »
If the voltage on the intercom line is too low it may not be enough to power the Plantronics amplifier. Most Plantronics amplifiers can be powered off of the telephone line or optionally with batteries or an external wall-wart.

But since we do not know the model number of the amplifier we also do not know if it has this capability, however if it does, be sure to put a set of batteries in it.

In order for it to hang-up and release the relay and extinguish the led, you will need to add an external on-off switch to replace the function of the switch-hook.

From what I recall from many years ago, the train master or dispatcher would have a monitor amplifier that was bridged across the train order wire to listen for the station agents/telegraphers calling for him so he would he could perform other duties around the room without having to keep his headset on all day long when it was slow. This would be easy to accomplish if you would like to add one at a later date.
In any event try the circuit below with your 425 network.

Offline G-Man

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Re: Telephone System for a Model Railroad
« Reply #12 on: April 16, 2013, 03:30:37 AM »
By the way, the notation down at the bottom of the wiring diagram should have said for you to connect the Plantronics amplifier instead of headset!


If the voltage on the intercom line is too low it may not be enough to power the Plantronics amplifier. Most Plantronics amplifiers can be powered off of the telephone line or optionally with batteries or an external wall-wart.

But since we do not know the model number of the amplifier we also do not know if it has this capability, however if it does, be sure to put a set of batteries in it.

In order for it to hang-up and release the relay and extinguish the led, you will need to add an external on-off switch to replace the function of the switch-hook.

From what I recall from many years ago, the train master or dispatcher would have a monitor amplifier that was bridged across the train order wire to listen for the station agents/telegraphers calling for him so he would he could perform other duties around the room without having to keep his headset on all day long when it was slow. This would be easy to accomplish if you would like to add one at a later date.
In any event try the circuit below with your 425 network.


If the voltage on the intercom line is too low it may not be enough to power the Plantronics amplifier. Most Plantronics amplifiers can be powered off of the telephone line or optionally with batteries or an external wall-wart.

But since we do not know the model number of the amplifier we also do not know if it has this capability, however if it does, be sure to put a set of batteries in it.

In order for it to hang-up and release the relay and extinguish the led, you will need to add an external on-off switch to replace the function of the switch-hook.

From what I recall from many years ago, the train master or dispatcher would have a monitor amplifier that was bridged across the train order wire to listen for the station agents/telegraphers calling for him so he would he could perform other duties around the room without having to keep his headset on all day long when it was slow. This would be easy to accomplish if you would like to add one at a later date.
In any event try the circuit below with your 425 network.


Offline DavePEI

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Re: Telephone System for a Model Railroad
« Reply #13 on: April 16, 2013, 05:24:48 AM »
Speaking of Plantronics:

Does anyone know of a source for replacement foam pads for the earphones and microphone on Plantronics headsets. Offhand, I don't have the model number of the Plantronics sets I have, but I got a whole bunch of them from a defunct call center I got a number of Centrex phones from a year or two ago. The headsets were is good shape, other than the foam (earpads and microphone) was badly deteriorated.

I would love to be able to put some of these to use, and to share the remainder with others. Later today or tomorrow I will go over to my storage area and get the exact model number of the headsets. If memory serves me correct, they may all be M-10 or M-12  headsets (or is that the amplifier no. only). At any rate, I will check the first time I get a chance.

Dave
« Last Edit: April 16, 2013, 05:40:24 AM by DavePEI »
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Offline twocvbloke

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Re: Telephone System for a Model Railroad
« Reply #14 on: April 16, 2013, 06:13:43 AM »
Speaking of Plantronics:

Does anyone know of a source for replacement foam pads for the earphones and microphone on Plantronics headsets.

If you're willing to fund the red dragon, ebay has plenty of the earpads going cheap (genuine ones are insanely expensive!!):

http://www.ebay.ca/itm/251251456550

They're usually all the same size pad, so should fit fine... :)

As for the mic foam, there's some on ebay, but they seem pricey for just the one piece, it'd probably be easier to do without, unless you really need the pop filtering properties of the mic foam... :)