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Phonesrfun's Step by Step demo switch

Started by Phonesrfun, November 26, 2009, 08:05:24 PM

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Phonesrfun

Or maybe a better title would be "It's a good thing I'm single!"

Last summer I bought some step-by-step switches from a guy in Oregon, and this stuff has been burning a hole in my concience for a while because I haven't done anything with it.

I have been playing around with it the last few days, and my test bench is the floor of my den.  Here is a picture.  Anyway, today I got the connector to work.  I can dial a number and have it connect and ring through, and answer.  These old switches are kind of elegant in their own way, but large, bulky and complex.  My intent is to build a step by step demo switch with three sections;  A line finder, a selector and a connector.  I figured I needed to start at the end of the train with the connector, and work my way backwards.  Quite a lot to learn, read, and absorb.  In other words, I am nuts.

It is cool to dial a number and see the switches ratchet up and over to select the proper contact on the banks of the switch.

So, for what its worth, that's what I have been doing the last few days.
-Bill G

gpo706

Bill,

Looks like my corner of the living room I "annexed" for my Dictograph experiments
"now this should take five minutes, where's me screwdriver went now..?"

Phonesrfun

Experiments are so much fun, aren't they?

-Bill G

Dan/Panther

Looks like my dining room, only neater.
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

gpo706

What V these strowger units run on?

Now you got me tempted, dammit
"now this should take five minutes, where's me screwdriver went now..?"

Phonesrfun

48v DC, positive ground.  It is a real brain thing for me to get used to seeing a ground symbol used on a schematic and having it be positive and the "battery" lead be a negative voltage.

-Bill
-Bill G

Phonesrfun

#6
I have been working a couple weeks on this project.  I obviously need to build a rack for it and get it off the floor.

The project has definitely grown in size and scope.  It is absolutely amazing how much it took just to connect a phone conversation back in the good old days of electromechanical switching.

Since I don't have a line finder switch, I have to use one phone only as the originating phone.  I have it hooked up to be able to dial one of two extensions.  The electronic breadboards you see are the things that generate the dial tone (old fashioned dial tone), busy signal, and fast busy.  The yellowish colored plastic box with the clip leads is an old key system interrupter that I use to interrupt the ringing signal to the called phone.

The first Strowger switch on the left is called a selector and is the switch that gives dial tone and accepts the first digit, then transfers the call to the second switch which is called a connector.  It accepts the last two digits; provides busy signal if the called phone is off the hook, or rings the phone if it is idle.  Once the called phone lifts the receiver, this switch sets up the talk path.  

When the calling party hangs up, all switches are reset.

It is fun to watch.  My camera is capable of making a video, but I have never done that.  I think it would be fun to post a video of this thing in action.

The interesting thing is that this is only part of what it used to take to make calls in a central office.  Basically, they needed not only two switches, but another switch in the series for each digit.  So, a 7 digit number would take a line finder, (Which does not accept digits); 5 selectors for the first 5 digits, and one connector for the last two digits.

They would have needed a set of these for each potential number of simultaneous conversations going on in any central office at any given point in time, especially during peak hours.

The point of all this is to kind of lift the curtain on the back office part of rotary dial telephones as they existed in times past, just to give some background on the part of rotary dial telephones that we sometimes take for granted.

An electronic central office of today is mostly a computer and can be housed in a relatively small building.  The electromechanical switches of yesterday were, argueably, computers in their own rights, but needed multistory buildings that were entire city blocks large.  

Switches of yesterday had a pair of copper wires coming in for each subscriber line hooked to it as well as for each interconnecting line between it and other central offices and to long distance facilities.

Now days, with multiplexed and channelized concentrators, a relatively small number of actual wires come into a central office, at least in comparison to days gone by.  That is fast becoming even more channelized, if you will, by voice over IP technology.

The interesting thing is that with all this channelizing and using multiplexed wiring and fiber optics, and satellite communications, we don't see that at our houses, for the most part.  The red and green wires we see coming into our RJ-11 jacks at home are just like they were back in the 1920's

Oh well, enough rambling.  Here is the status of my project as of today.
-Bill G

bellsystemproperty

You sir, are a genius.  ;D Please do post a video, your switch is very interesting. My PBX was like the central office for my house, and I think I found a new one I'm going to get to replace the dead one. I have a Comkey 416 system I'm learning to use.

Dennis Markham

Very interesting Bill.  I was able to see a switch set up at the small local Mason, MI TCI show a few years ago.  It was fun to watch things move and click and make noise to complete a call.  It's all Greek to me.  It would be great to see a video of yours when you're ready.

bellsystemproperty

Ok Bill I just won a Panasonic 1232 to replace my dead 616. The 1232 was cheaper than all the 616s on eBay. so why not? Now I can reconnect my 41 phones.  ;D

Phonesrfun

BSP:

Congratulations on the 1232.  I seem to remember reading somewhere that it needs to be punched down, as opposed to the plug and play RJ-11's that the 308 and 616 have.  That should not pose a problem, because it should be pretty straight forward.

As far as being a genius.... well if I were a genius, you would think I would have the patience to sit down and get my camera to do its thing with video.   I am no genius with switches either.  Believe me I had to ask a bunch of questions of some knowlegeable people, including the guy in Oregon that built this item:


http://tinyurl.com/yjtkp7t

Since the above is his auction that ended, I don't know how long that link will be good.  Anyway, he has been a lot of help.  I bought much of the equipment for mine from him.

I guess I have more patience with switches and such than I do with cameras, but I'll figure it out, meaning I'll haul out the instruction booklet.

-Bill
-Bill G

bellsystemproperty

#11
Ok, you're not a genius, but you're pretty smart.  ;) I've heard the same thing about the 1232 being punch down, but that's fine with me. It's going to take a while to come via UPS because of all the Christmas traffic.
It makes me feel good knowing I didn't buy this one http://tinyurl.com/ydrewhq for $950 when I got this one http://tinyurl.com/y8ulcz8 for $40!

BTW shipping was $30, a bit high, but not $78 as the auction showed.

Phonesrfun

I would say you got a great deal!  I spent more than that on a 308.  Hopefully the phone from the 616 will work for doing any programming, but you should be good just with the default program.  I found that the proprietary phone I got with the 308 will work for the 616 for the basic things like time of day and soem other basic things.

-Bill G

bellsystemproperty

Mine didn't come with a phone. This one doesn't either, but I have used the default programming ok. I just love how the PBX supports pulse dialing, so many modern ones don't.

Phonesrfun

Let us all know how it works for you.  I am interested.
-Bill G