I just picked up this phone from a local ebay seller and am trying to find information about it. The bottom is marked "DBK1001T" and there is an illegible decal. The phone is quite small, measuring about 6" x 4.75" at the bottom. I tried connecting the end of the line cord to my phone line, but I got no dial tone.
Is this phone capable of working on a standard phone line? Where can I find a wiring diagram? There us a terminal block, but the terminals are marked with numbers only.
Thank You
Larry
Ericsson used an alphanumeric classification system for equipment.
DB are telephone sets (D) made from Bakelite (B). The third letter was for the manufacturing location or country, and I think K is Finland.
So, I believe this is the same set that was designated as DBH-1001 in Sweden, which was the first all Bakelite telephone made in 1931.
I think I have a diagram for the DBH-1001 somewhere... will try to find it.
This set is usually quoted as the inspiration for the Western Electric 302.
Really nice find.
Well, I still don't have a circuit diagram, but I found the article of the nomenclature system they used.
I was wrong about the third letter. K stands for a small version of the case. I think, possibly only containing a buzzer rather than a larger ringer.
Here is the ER article about the designation system.
Thank you for the information. I found the DBH1001 diagram on the TCI website (link (http://www.telephonecollectors.info/index.php/document-repository/doc_details/1072-lme-209422-dbh-1001-1002-1003-1051)), and I was able to connect the phone so that it worked. The sound quality from the transmitter is awful. It sounds like a 1920s candlestick type. My problem before was that the test line cord I was using is bad.
The phone, as I mentioned, is REALLY small, so the 'K' for small case makes sense. The phone looks rather like a toy. It has one of those Ericsson gong-less ringer gadgets which makes loud clicking sounds in lieu of ringing. I am guessing that the "44-41" printed inside means that the phone was made on the 44th day of 1941. Here is the ebay link for the phone: ebay link (http://www.ebay.com/itm/321828196935). The seller told me that his father collected phones and that this came from his collection. I met him today locally to get it. Unfortunately, a very large chunk of something flew into my car at 70MPH on the freeway on the way, so there is about another $1500 of car repair costs involved with this acquisition.
Larry
Quote from: LarryInMichigan on August 18, 2015, 09:18:04 PM
Thank you for the information. I found the DBH1001 diagram on the TCI website (link (http://www.telephonecollectors.info/index.php/document-repository/doc_details/1072-lme-209422-dbh-1001-1002-1003-1051)), and I was able to connect the phone so that it worked. The sound quality from the transmitter is awful. It sounds like a 1920s candlestick type. My problem before was that the test line cord I was using is bad.
The phone, as I mentioned, is REALLY small, so the 'K' for small case makes sense. The phone looks rather like a toy. It has one of those Ericsson gong-less ringer gadgets which makes loud clicking sounds in lieu of ringing. I am guessing that the "44-41" printed inside means that the phone was made on the 44th day of 1941. Here is the ebay link for the phone: ebay link (http://www.ebay.com/itm/321828196935). The seller told me that his father collected phones and that this came from his collection. I met him today locally to get it. Unfortunately, a very large chunk of something flew into my car at 70MPH on the freeway on the way, so there is about another $1500 of car repair costs involved with this acquisition.
Larry
Shouldn't go 70 on the Jeffries ! ;D
or 41st day of 1944? They didn't get bombed out in Sweden. Looking at the components they do look more like 1940s than 1930s.
It was I-96 in Livonia. That freeway was completely rebuilt about a year ago.
Sweden was officially neutral during the war, though they allowed the Germans free passage through their territory.
Larry
Norwegian EB catalogue 1938.
The closest I came, This was made in Norway, Larry's seems to be Swedish. My guess will be a diagram close to this:
(http://www.classicrotaryphones.com/forum/index.php?action=dlattach;topic=9998.0;attach=73344;image) (http://www.classicrotaryphones.com/forum/index.php?action=dlattach;topic=9998.0;attach=73344;image)
Yellow= Ring Black=Tip Red= ringer (connects together with Black)
dsk
I haven't found it in any of the Ericsson catalogs that I have, but I have a list of Ericsson catalog numbers with cross reference to circuit numbers:
DBH 1001 209422 209446 209434 128075
DBK 1001 209423 209447 209435
DBK 1101 209427 209451 209439 230342
This matches the circuit number for the DBH 1001 that is on the TCI site.
I also have not found it in my full text search index of the entire old Ericsson Review.
:) I see no difference, but if it has a buzzer, it will probably be like a ringer and 1 microfarad capacitor, Load about 2-3 REN
dsk
Very nice find. These are quite rare.
Here are my 2 cents:
I know this particular Phone as a knarretje (in Dutch, but the Swedish word knar seems to mean buzzer). It is a smaller version of the model 31.
It was meant to be an extention Phone, like for bedrooms, or as a normal unit for office environments where loud bells were not wanted.
It comes with a buzzer or without one.
The designation 1001 seems to be for a dialless version, so maybe this one was converted?
44 41 as an Ericsson date code would mean year and week number. (possible the other way around).
The is a page in the Swedish database here:
http://www.stsf.org/Schema/DBK/DBK1001.jpg with schematics.
It is also in the 1934 catologue om the Ericsson History website.
Both are pictured below.
Notice the slightly different anti sidetone circuit. The last one has a later LME solution. If it has a buzzer, it should have 2 capacitors.
If the telephone is made after this diagram, a defect capacitor will make it silent. Just short out to test.
The telephone pictured has a 3 wire cord, that looks more like the first diagrams.
Try to connect black and yellow to the line.
dsk
Thank you for the information. My phone is quite a bit smaller than the ones shown in the Ericsson catalog. It is about 153mm long by 121mm wide. The height in the back is about 99mm.
The phones works when the line is connected to terminals 1 and 3, and the buzzer works when the line is connected to 1 and 5.
The phone is in pretty good condition, but there are several chips in the bakelite along the edges.
I was guessing that the "M4141" on the condenser indicated a 1941 manufacture date.
The edge of the dial is stamped: "TELEFON A.-B. L.M. ERICSSON * STOCKHOLM 02 41". Again, I would guess that the "41" indicates a 1941 date.
Larry
Quote from: Matilo Telephones on August 20, 2015, 02:28:34 AM
Very nice find. These are quite rare.
Here are my 2 cents:
I know this particular Phone as a knarretje (in Dutch, but the Swedish word knar seems to mean buzzer). It is a smaller version of the model 31.
It was meant to be an extention Phone, like for bedrooms, or as a normal unit for office environments where loud bells were not wanted.
It comes with a buzzer or without one.
The designation 1001 seems to be for a dialless version, so maybe this one was converted?
44 41 as an Ericsson date code would mean year and week number. (possible the other way around).
The is a page in the Swedish database here:
http://www.stsf.org/Schema/DBK/DBK1001.jpg with schematics.
It is also in the 1934 catologue om the Ericsson History website.
Both are pictured below.
How did you make the cross-reference to that catalog page with DE752 and DE3010. I looked at the very same page when browsing the catalog and didn't see a direct relation.
Quote from: LarryInMichigan on August 20, 2015, 06:39:30 AM
The phones works when the line is connected to terminals 1 and 3, and the buzzer works when the line is connected to 1 and 5.
That is indeed what the diagram tells us it should do.
The diagram also indicates that you can install a strap between 3 and 5 (EB) or connect an
Extension
Bell at those points.
It seems to me that the DBK 1001 replaced the CG552 from the same catalog, which was noted on the handwritten model page.
You are probably right again. The metal plungers were later replaced with bakelite, at least on the more common telephones.
dsk
I just reassembled the phone. The sound quality from the metal diaphragm transmitter is quite poor.
Here are a couple of blurry pictures showing this phone with two other related models, a Dutch PTT Ericsson Rijen phone and a British GPO 300 series. The GPO phone dwarfs the DBK1001T.
Larry
I don't know why the US transmitters was better designed than European? But they definitely were.
The DBK1001T transmitter needs to operate at an extremely low current and voltage so a LB transmitter may be the best replacement.
dsk
Quote from: dsk on August 25, 2015, 01:45:48 PM
I don't know why the US transmitters was better designed than European? But they definitely was.
The DBK1001T transmitter needs to operate at an extremely low current and voltage so a LB transmitter may be the best replacement.
dsk
You mean a CB (common battery) transmitter would be better?
@Larry: Are there any markings on the transmitter that might identify it for LB vs. CB operation?
Local battery transmitters use 1.5-4.5 volts. finer granulate is better until clogging up, it is a lot of parameter.
The circuit in this telephone has a current passing trough the balance winding, so not everything goes trough the transmitter.
I would just tested with different US capsules.
dsk
On the back of the transmitter is "RLA1401" and "200Ω". The handset is designed in such a way that the shape and size of the transmitter capsule are very important. The capsule fits exactly into a frame in the handset and the mouth piece fits tightly against the top of it.
Larry
The RLA 1401 is at the bottom of this page, equiv. RLA 1612, but the earlier description applies.
Indeed 200 Ω unit, seems pretty high. This confirms it is at least a CB element.
Perhaps you should try to measure the current it draws on your line.
I connected a 390Ω resistor in parallel with the transmitter so that it doesn't continuously generate static, but the frequency response sounds like a metal diaphragm transmitter on 1920s candlestick. I am a bit surprised that Ericsson was selling phones with transmitters like this in 1941. I should be able to use the phone, but the person on the other end will wonder if I am speaking through a metal tube.
The phone is rather cute though.
Larry
I just tried using a T1 transmitter and it actually does seem to fit well enough in the handset to be usable despite the size and shape difference.
Larry
The transmitter seems pretty large for a tiny phone like that. T1 is about 7 mm smaller.
I guess the handset is full-size?
You allready have the anti-sidetone circuit across the receiver. the current goes trough a 32ohms winding, splitting up in to the 200 ohms receiver, and the anti sidetone winding of 600 ohms. The 200 ohms transmitter containes finer (smaller) granulates, it will be more sensitive, but clog or burn easier. The maximum current to the phone are described as low as 30 milliamps.
You loose 1/4 in the anti-sidetone winding. so the max in the transmitter should be: 22.5 milliamp!
Just like in Kellog's triad circuit (redbar?)
dsk
The handset is the standard size.
Larry