Hi All. Question for tech guys:
Found this in a barn sale, just picked it up yesterday. It's a cool looking old phone with a separate box, no dial, just a crank. Inside, there are four terminals for hookup: L1, L2, BAT+ and BAT-. I attached a pair of wires to the L1 and L2.
Searched the web and to best of my knowledge, it's a Kellogg model 900 from around 1933 or so.
I need to know how to get it to ring. L1 and L2, understood, but where would I put the jumper to activate the bell circuit using only two wires? I plan to attach it to my recently fully-operational 551A switchboard. Maybe I should direct this question to the tech thread....?
Supposedly it was in operation for years, then stashed away, so the last time it was used, it worked. Pretty grimy when I got it, so I went thru it, cleaned it up, and here's what I have:
As configured, this is a local battery phone. So it could be connected to one of the 10 trunk (outside line) jacks rather than one of the 30 line (extension) jacks...Otherwise, you would want to make sure the generator is permanently disconnected (so as not to damage the 551)and that you add a capacitor in series with the ringer.
Kellogg hand generators are factory wired so that your own ringer is disconnected while turning the crank. However, at all other times, the ringer is connected to the two line wires. If you observe the generator contacts, you will see which ones open while the crank is engaged.
I think the phone is a Kellogg Masterphone 900.
Someone correct me if I'm wrong.
Quote from: poplar1 on October 30, 2017, 03:54:20 PM
As configured, this is a local battery phone. So it could be connected to one of the 10 trunk (outside line) jacks rather than one of the 30 line (extension) jacks...Otherwise, you would want to make sure the generator is permanently disconnected (so as not to damage the 551)and that you add a capacitor in series with the ringer.
Kellogg hand generators are factory wired so that your own ringer is disconnected while turning the crank. However, at all other times, the ringer is connected to the two line wires. If you observe the generator contacts, you will see which ones open while the crank is engaged.
Thanks for the info!
OK, there are three terminals; +, -, L1 and L2. If I L1 and L2 to the trunk line 1, what do I do with the BAT connections? Also, there is a series capacitor inside the box already so that should be OK.
I see the contacts the close when you crank the generator and open when it's stopped. But there is a NC contact as well, possibly the one that I need to disconnect.
Quote from: shortrackskater on October 30, 2017, 07:25:35 PM
I think the phone is a Kellogg Masterphone 900.
Someone correct me if I'm wrong.
You are correct. They also call it a "pyramid" phone, probably because of those two finger holes on the top. And because the handset is shrouded, it seems to be a popular art-deco design as well. What a cool design from 1932.
If you connect the phone to a trunk, then you won't have to disconnect the generator. But you will still need a battery (or other filtered DC source) for the transmitter in the 900 set. Either 3 Volts or 4.5 VDC connected to + and - in the bell box will be OK.
So then, if I use this phone for line 1 trunk, and make a call to the switchboard, I assume I'll need a set of bells on the switchboard - it doesn't have a bell on it, but I did find a pair of wires under the key shelf, with nothing attached to them. I assumed it was for a foot switch, but not sure. Maybe it's for a bell? I'll trace those wires back to the MISC terminal block and see where they lead.
I can use a small switching power supply inside the switchboard attached to the 15 volt DC supply I installed there, and reduce it down to 3 volts, then use the other pair of wires (black, yellow) to feed the phone. A separate wall jack attached to the switchboard should do the trick.
There are indicator lights on the switchboard for outside lines and that buzzer that I can switch on or off possibly will be an audible indicator for trunk lines as well as station lines?
So, if I understand this, I pick up the 900 phone, the trunk lamp will illuminate. Then if I crank it, a bell attached to the switchboard will ring. I assume a bell connected to trunk line 1 of the switchboard will ring.
Thanks for the insight.
If the 900/Kellogg subset are connected to a trunk, then the lamp won't light up when you pick up the handset on a 900. The trunk is looking for 90 Volts AC, same as a telephone line, so it won't light up unless you crank the Kellogg generator (with the phone hung up).
It's been a while since I operated a 555, but I seem to recall that the signal will "lock in": once it receives a burst of AC ringing current, then the lamp will stay lit until you plug in. The same buzzer that is used for the 30 extensions will also buzz for a trunk call. No additional ringer needs to be added to the PBX.
Poplar1 thank you. I will get it wired that way. If this phone will light the switchboard lamp, the rest should be a piece of cake.
I'll be working on that.
Wow, in pristine condition! Nice find!
I do love those 900 pyramid phones, I have two. They don't look as nice as yours. And that box looks to be in excellent condition! Great find, I'm jealous, for sure!
Benny
I have one too. I almost got rid of it before I actually started collecting phones again. It still stuffed in a cupboard.
Question:
Are those original or original style feet? Can you post a picture of the bottom so I can get a closer look?
They do look much longer than either of mine. I thought mine were just wore down from use!...They may have been replaced when the set was refurbished.
The original feet were hard as a rock and two of them were "smooshed" because the metal plate was slightly crooked in the corners.
So I used a pair of pliers and crushed them off - they broke easily and left behind the rivet that held them in place, unscathed.
Then I used this part:
https://www.mcmaster.com/#9540k724/=1a35mnd
They are exactly the same size and same hole in the center, simply slipped them on to the existing rivet. Fit perfectly and look exactly as the original.
McMaster Carr also carries this style:
https://www.mcmaster.com/#9540k723/=1a35q12
Same dimensions, but more square on the outside edge. It would work as well if you don't want the rounded surface as in the picture. Not sure how the original feet looked but I'd guess they were more square so this number might be preferable.
I just happened to have the first style in my hardware stuff.
To the experts here, Kellogg 900 was used on magneto, and CB some had ringers in the pone, did they all have ringers? Was it different induction coils, or just changing some wires?
Do you have links to various schematics?
dsk
https://gyazo.com/431d70436eecb54dd7c7f1a564a020ed (https://gyazo.com/431d70436eecb54dd7c7f1a564a020ed)(https://gyazo.com/431d70436eecb54dd7c7f1a564a020ed)
If you post the schematics, hopefully glued in to the subset, you may get exact advice's. Since this probably are a phone used on short lines it will probably work well with a strange connection; Connect the line to the 2 battery terminals, and short the 2 line terminals. On CB manual board: Voice path should work OK, but no Ringing. To get rining a capacitor from the ringer terminal to one of the battery terminals, (not sure witch of them, you have to try) The capacitor should be a normal ringer capacitor probably rated at 1 microfarad, but test with whatever you have.
This is based on the idea of that you have a phone with noting else tan the hookswitch under the cover, and a regular Local Battery subset.
dsk
I think I have it working correctly. Added a small 3 volt DC supply inside the switchboard and tied it into an unused pair of wires, out to the phone. Then I tied the trunk Line 1 into that connection. I have a 15 volt DC supply feeding this small module. The other supply is a ring generator that bypasses the hand crank.
When I crank the magneto on the phone, the trunk line 1 lamp lights and stays lighted. Plug the jack in, the phone is active.
Further testing will determine if it works 100%. Here's the power supply I added: