WWI Model 1914 Service Buzzer and telephone with prices
See lower part of page for recent selling prices.
Model 1914 Service Buzzer / telephone and telegraph combination. It works!
If you are doing an exhibit of telegraphy, see my telegraphy/Morse code page for suggestions: https://sites.google.com/site/scr625/telegraphy-for-children
The Model 1914 Service Buzzers by themselves are over a century old. First used by men born in the late 1800s, now, as part of my hands on working exhibits, they are used by youths born after 2010. Even when doing a Civil War telegraph exhibit, I bring along a Service Buzzer in addition, because it is easier to explain Morse Code with a buzz rather than a click-click. A telegraph a child can't touch or use will interest them for less than five seconds, but a telegraph they can use may interest them for several minutes.
A useful document on various types of WWI communication:
https://www.usmcmuseum.com/uploads/6/0/3/6/60364049/nmmc_wwi_military_communication_resource_packet.pdf
One of my Service Buzzers has a deformed battery compartment, where I can't fit in the D cells for power. I made up a AA battery fixture, and soldered wires where shown, where the black wire is -3 v, the red wire is +3v, and the white wire is ground.
This is an early WWI combination telephone and telegraph. With separate earpiece and mouthpiece, with no crank and no ringer. It needed constant monitoring to know when a message was incoming. Both telephone and telegraph used the same lines. Requires +3 volts and -3 volts, of an obsolete battery type. Requires a second telephone or resistor hooked up to the lines to hear your voice in the earpiece. A correct Service Buzzer should have brown twisted pair wires to the mic and earpiece.The headset has a brown twisted pair cord 5.5’ long, and a black headband, with no model number or manufactures ID on it. The mic cord is 3’ long, with no model number or manufactures ID on it. It must have a push to talk switch on it.
An Army manual can be found online, with technical information, by searching for "Field artillery course for provisional second lieutenants". It is a scan by Google of a 1917 Army manual, downloadable and printable for free in .pdf format.
See "Lecture XI" of manual, Google pages 76 - 84
Some notes from the manual:
The key is opened and closed several times to get the attention of the operators at other stations.Then he would key the call letter of the station he wants, and key "fone" if it is to be voice communication. Keying the service buzzer will set off a switchboard if one is in use. The condensers are for certain use with with Morse signalling - not sure what they mean there. The manual has notes on adjustments, too. Using the service buzzer to send, and the phone receiver, was considered more reliable and sensitive than a regular telegraph with a "sounder" to receive.
Sept 2017 - I found online a scan of a book "Technical Equipment of the Signal Corps. 1916". I bought a print on demand hard copy through Abe Books for $15. Over 500 pages of information.
I purchased my first one on ebay for under $40, but it was missing the mouthpiece (microphone), earpiece and condensers. Rigging up four D cells for power, adding three .1 microfarad capacitors as the condensers, and using a handset from an EE-8 field telephone, it worked! Hooked up to an EE-8, the voice volume is fine, but the telegraph clicking in the EE-8 is very loud, and I don't recommend using the telegraph when hooked up to a telephone. It appears to send about a 100 volt pulse down the line, so I think it would be best to avoid using it. The rated value for the condensers is .25 ufd each. A correct mouthpiece should have a press to talk (PTT) switch , when the phone is in use, to prevent battery drain. .
There are a lot of adjustments, which I will cover later. It seems that all the settings are related to the telegraph. A wrong setting can cause some significant arcing, or considerable shock - believe me. I don't know if hooking it up to a crank telephone and cranking on it would damage the Model 1914 or not. I would recommend removing the crank if you hook one up.
I replaced the .1 ufd caps with .22 ufd, and by adjusting the two screws that contact the leaf spring at the end of the coil, it buzzes now, instead of just clicking. This is a hit or miss adjustment, and just a slight bit off, even a quarter turn, makes a difference between buzzing, clicking, or nothing at all. The small screw is a coarse adjustment, and the large screw is a fine adjustment. Looking at the close up picture near the bottom of the page, the coarse adjust has 3 threads on the right side exposed, and the fine adjust has 8 threads exposed. There is less than a eighth turn range on the coarse adjust, and less than a quarter turn range on the fine adjust. The leaf spring should be just slightly away from the end of the coil, and get pulled to the coil when the telegraph key is pressed. The gap between the spring and the coil is about the thickness of four sheets of normal to thin paper. It's a rather harsh sounding tone, and very loud when hooked up to an EE-8 telephone, even while using only a 1.5 volt buzzer battery. The phone batteries need to be installed to use the buzzer, too. I still don't see any difference when the condenser switch is in or out.
The telegraph output voltage is dependent on the load. I don't know what the proper load impedance should be, and this is what I've found: With a 200 ohm load, the voltage is 30 volts peak to peak, 1K ohm is 100 volts, 25K ohm is as high as 500 volts. So - don't operate the telegraph without load, and I think a 510 ohm, 1/2 watt resistor will be what I will use.
So - To do a display using the 1914 Service Buzzer and another telephone, to demonstrate the buzzer, switch in a 510 ohm resistor across the output, and the telephone disconnected from the circuit. Depending on what load you use, you will need to adjust the fine adjust, as noted above. To use the phone circuitry, switch out the 510 ohm resistor, and have the other telephone connected directly to the Model 1914 output.
The condensers are rated at .25 ufd, but the ones on this service buzzer measure .3 ufd, .8 ufd, and 1 ufd. Way off, but it seems to work OK. A PL-55 plug with the shell removed will fit into the Service Buzzer jack. It works now, after cleaning contacts, and making mechanical adjustments. The buzzer leaf spring adjustments were off considerably. I am using a WWII 4A microphone with a EE-8 field telephone F1 transmit element installed, and a 60's vintage H-113 headphones. The transmit is strong on both, but just so-so on receive, as a pair or with another field telephone.
Note on mic and headphone - For a nearly authentic mic, certain RS-38 mics are close in appearance, others are too deep to fit in the case. The R-3 and R-18 headphones are a good substitute appearance wise. However, both are too small to install a more modern, functional transmit or receive element. That's where a 4A mic with a F1 transmit element and a WWII HS-30 headset with C410 transformer will work if you want a functional unit.
To measure battery voltage, without actually measuring at the battery: (I tried this on one without a headset or mic attached, which I don't think should make a difference.) Attach the ground lead of the voltmeter at the "T" terminal of the transmitter (on bare metal, not painted). Condenser switch position in vertical, "B / T" switch to "B".
Measure +3 volts at the right side of the condenser closest to the coil.
Measure -3 volts at the right side of the condenser furthest from the coil.
Sept 2011 Swapped the R-18 receiver I started using, due to lack of sensitivity, for the R-3 receiver from my TG-5 telegraph. the receive volume is much better now.
Nov 2011 I purchased a second Model 1914 Service buzzer, without mic or earpiece, on ebay, for $15!
I don't watch the overpriced ones, but this is what's sold on ebay recently:
Feb 2016 An EE-1A service buzzer/phone with headset, no mic, sells for $89. Larger, functionally like the Model 1914 Service Buzzer, but in a wooden case.
Jan 2022 - A service buzzer in good condition, with no mic or headset, sells for $90.
Mar 2022 - A service buzzer with mic and headset sells twice - First for $68, then for $52.
Nov 2022 - A Service Buzzer modified with handset sells for $56.
Dec 2022 - A Service Buzzer modified with handset sells for $45? The one above was resold?
Dec 2022 - A Service Buzzer in fair condition, with headset, free shipping, sells for $59.
Jan 2023 - A service buzzer in good condition, with no mic or headset, sells for $87.
Feb 2023 - A service buzzer with bad leather, very good interior, with mic and headset, sells for $85.
Mar 2023 - A service buzzer in good condition, no mic or headset, sells for $139.
Apr 2023 - A service buzzer in good condition, with mic, sells for $130.
Apr 2023 - A service buzzer in fair condition, no mic or headset, sells for $40.
Jun 2023 - A service buzzer in fair condition, with mic and headset, no headset strap, sells for %55, with free shipping.
Jul 2023 - Three service buzzers, two in good condition, one stripped down, sell for $125 (total).
Aug 2023 - A service buzzer in good condition, with no mic or headset, sells for $100.
Aug 2023 - A service buzzer in fair condition, with no mic, headset or condensers, sells for $85.
Dec 2023 - A model 1913 service buzzer with mic and headset, in good condition, sells for $150. The first I have ever seen.
Jan 2024 - A service buzzer in fair condition, with no mic, headset or condensers, sells for $81.
Jan 2024 - A service buzzer in fair condition, with mic, headset and adjustment tool, sells for $150.
Feb 2024 - A service buzzer in fair condition, with no mic or headset, sells for $100.
Mar 2024 -A service buzzer in fair condition, with mic, headset and adjustment tool, sells for $175.
Watch out! A friend of mine bought a service buzzer that was missing two of the three adjustment screws, and a coil connection. The thread sizes are no longer available, but with some creativity we made it work. Small things are easy to overlook, especially if the pictures are poor. Replacing the screws and coil connection, we were able to get it working. He made an adapter like the one pictured below, and used 4 "D" cells for power. Using a 428 ohm load resistor, his output voltage was about 100 volts peak to peak (on an oscilloscope) with condensers not switched in, 80 volts p-p with condensers switched in.
September 2017 The service buzzer I just bought for $53 (with free shipping) has the mic and headset with it, which is not very common. The battery compartment was hard to open, and I expected to find corroded batteries, but instead found the service buzzer line plug and wire rolled up inside! In years of collecting and watching ebay, I have seen very few. The wire is about 3 ft. (1 meter) long. It didn't have the adjustment tool though, which are also pretty rare. There was also a wood block in the battery compartment, which is to adapt from the four "type A tungsten" batteries to four "D" cells. The wood is exactly 1 inch thick, plus the thickness of the feed through terminals on both sides.
After cleaning the headset and mic terminals, and temporarily attaching batteries and a 1K ohm load resistor, when I depress the talk button on the mic, I can hear myself in the headset. The buzzer portion is working too.
Nov 2022 The Service Buzzer is not buzzing - The batteries are low, and the "B"uzzer" / "T"elephone rocker switch is loose, and readjustment was needed. The buzzer works best when the rocker switch is in the "T" position, but I'll look into that another time.
February 2020 I bought another service buzzer for $20, in good condition, but no mic, headset or adjustment tool. I spent half an hour cleaning connections, eyeballing the physical adjustments, and the buzzer works. It's great to have a working one to compare to a newly purchased one to. I used four "D" cells and the battery adapter for power.
Below is a line clamp, used to connect from the buzzer line cable to the transmission line, with a "bed of nails" to pierce the insulation. Line clamp and photo by Mike B.
I made a couple D cell battery adapters, using 2 ea 1/4-20 x 1 1/4 inch brass screws (ground down to length later). Wood block is 1.5" long, 1.25" high, with thickness to accommodate the screws. The tip to tip length of the screw head to the end of the nut is 1.25". Grind off excess screw length.
The original batteries were 4 type "A" tungsten battery in two cardboard tubes. A pair of batteries were 6.25 inches long. Later replaced by the BA-1 battery. A BA-1 battery compared to two "D" cells.
(Below) A load resistor used, when not connected to another device. About 510 ohms would be a reasonable value.
1914 Service Buzzers used as a pair - The telephone transmit amplitude is good on both, and the receive is a little weak on both, but receive amplitude is good internal to each unit. When the service buzzer (telegraph) is used, the amplitude is about 125 volts peak to peak, which is very loud in the opposite receiver. Because the amplitude is so loud in the receiver, I do not recommend using the service buzzer except connected to a load resistor. Do NOT use the buzzer when connected to a telephone!
20 volts per division vertical scale
FYI, the spike you see in the voltage is why old car ignitions with points used a condenser.
If you are using a Service Buzzer by itself, use a 510 ohm resistor as a load. Any resistance near that is OK. See photo above.
Railroad telegraph comparison - I have a railroad type telegraph, which operates at less than 1.5 volts. The type of "sounder" is the key to what voltage to use. The lower the ohms, the lower voltage is used. Mine is a 4 ohm sounder, which is as low as they go. I use less than 1 volt for the 4 ohm sounder. A 20 ohm sounder I have requires about 9 volts to operate. Others are higher, and will need a higher voltage. The net result is, don't use a regular telegraph sounder with a 1914 Service Buzzer - you will probably burn out the sounder in a short time.
Repair notes:
1. There a four screws to remove before pulling the assembly from the housing. They should have a white circle around them. Two are under the condensers, and two on the front side. Taking the wrong screws out may cause parts to come off and be damaged. there is one screw and a tab to remove to get access to the circuit on the underside of the assembly.
2. Where I needed to attach a battery wire to a steel battery contact, which can not be soldered to, I drilled a hole and screwed in a brass screw, which can be soldered to.
3. On the telegraph key adjustments, the small leaf on the bottom side of the key should make contact with the terminal below, before the key makes contact with it's terminal.
4. The screws that attach the parts to the base also provide the electrical connection to the underside wiring. To insure a better connection, turn all screws a half turn loose, then re-tighten.
When one of my service buzzers quit working, I thought it was a low battery, so I replaced the batteries. A readjustment might have corrected the problem, but I didn't think of that at the time.
To test the microphone and headset- see the diagram on my EE-8 repair page.
1. Mark all headset and microphone wires as to where they connect to the service buzzer.
2. Disconnect the headset and microphone from the service buzzer.
3. Temporarily touch a 1.5 volt battery across the wires OF THE HEADSET. You should hear a scratchy noise in the receiver. This means the headset works.
4. If the headset works, hook up one headset wire to one terminal of a 1.5 or 3 volt battery.
5. Hook up the other headset wire to one wire of the microphone.
6. Hook up the other wire of the microphone to the other 1.5 or 3 volt battery terminal.
7. If the press the talk switch and blow, you should hear it in the headset . If not, you probably have a bad wire or transmit element. If it does not work with 1.5 volts, you can try 9 volts, but only for a very short time.
Below- Coarse adjustment at the bottom - three threads shown.
Fine adjustment at top - eleven threads shown.
.
There is not much I can do by email to help you get a service buzzer working, but I am willing to try. If you can take detailed pictures like my adjustment pictures, it would be most helpful. dewnist@gmail.com