Desk telephone W 38
The desktop phone W 38 ( W ählapparat 38 ) was in 1938 largely by the company Siemens & Halske developed, built by different manufacturers under license and from the German Post in 1940 as a successor of W 28 used, the latter was nevertheless continue to be manufactured in parallel. The W 38 is the improvement of the almost identical model 36 from 1936, which was not approved by the Reichspost due to technical inadequacies and was only allowed to be used as an extension telephone .
General
The number switch type "NS 38" was used for the first time on the W 38 , at that time without the small aluminum dial . With an additional contact that short-circuits the last two pulses , this enables the mandatory pause required by the Reichspost when dialing between the individual digits, thereby avoiding incorrect connections in certain cases. Until 1940 the number switch (as in the W 28 and model 36 ) was locked when the handset ("receiver") was hung up . In terms of circuitry, this is no longer necessary - the block only has the effect of enforcing the "correct telephoning" ( pick up the handset, wait for the dial tone , dial the number ). The two-part, funnel-shaped projection (unscrewable lower microphone cover of the handset) with the three horizontal slots, which is directed towards the mouth, was adopted unchanged from the model 36. In contrast to the 36 model, the base plate is embedded in the housing. As a result, the side edges of the housing are not entirely at right angles to the tabletop. This assembly has the advantage that the base plate is flush with the housing and is optically "hidden". Mechanically, this solution was less clever, because the brittle Bakelite is much easier to flake off at the lower edges due to the material thickness being around half the thickness . Its successor, the W 48 , was built with this housing.
Appearance
The housing cover and handset of the W 38 are made of the thermosetting plastic Bakelite, mostly in high-gloss black. The ivory-colored luxury edition with a number switch with white numbers on a black or brown background was only available in very small numbers. The electrical and mechanical components are located on a solid metal base plate and are freely wired with cable harnesses . The double-coil alarm clock has two steel bell shells with different pitches, which produce a pleasant, harmonious sound. At the same time as the table model, a version for wall mounting was also produced, the "W 38 wall". There are also various special designs for telephone systems . From 1949/50 in the Federal Republic of Germany , the W 38 was replaced by the almost identical model W 48. Production was cut back during the war, which probably explains the rarity of these devices. The pre-war models up to 1939 and especially the ivory-colored models are absolute rarities. Mostly today (2015) you can still find a few post-war models from 1946.
Reichspost approval
It was approved in 1938. Nevertheless, the Reichspost did not order this device in large numbers until 1940. In 1941, 30,000 devices were already in use. The bell shells of the alarm clock were now made of pressed glass to save higher-quality metal for the war armor . In contrast to the metal bowls, these have a rather clanking, rattling, less beautiful sound. Compared to the Model 36, the bakelite of the case is thicker and the case screws are in a different location to avoid confusing the case parts with those of older models. The new number switch of the "NS 38" type now always selects two more impulses, i.e. when you select a 'one', the number switch generates three impulses, two of which are short-circuited again by the newly added nsr contact (reducing or break contact) become. The purpose of this change is a mandatory pause of more than 120 milliseconds between choosing two digits in order to avoid incorrect connections. This change can also be seen externally on the finger hole disc. To select the number 'one' you now have to make almost a quarter turn - that is, turn the disc forward three holes to the finger stop. The model 36, which continued to be produced, also received this new number switch from around 1940 - initially also with a mechanical lock. Compared to its predecessor, the W 28 , the electrical circuit was also slightly changed. It is technically no longer necessary to block dialing when the handset is on-hook, because the nsa (number switch, normally open contact) has now been switched behind the hook switch . In contrast to model 36, the arrangement of the components has been changed on the base plate. Transformer and capacitor changed sides, the hook switch was now arranged in the middle. The radio filter that can be used optionally in the model 36 is no longer provided. An enhanced sidetone suppression (with 0.3 microfarads condenser and 600 Ohm - resistance ) is located only in the first models of the W 38. The conventional 1-uF capacitor is the way as with the additional 0.3 uF capacitor Double capacitor housed in a common housing. Only in the W 48 (west) of the 1960s and in the W 61 (east) is a similar circuit found again.
W 38 - GDR
In the GDR , the W 38 was built for Deutsche Post by the former DeTeWe Fernmeldewerk Nordhausen (Nordfern, later VEB Fernmeldewerk Nordhausen or VEB RFT ) until the 1960s . The circuit was slightly modified compared to the Reichspost-W 38. The Ost-W 38 is available with and - very rarely - without an earth button . The glass bells were kept until the end of production. The standard color is black, a few specimens were made in wine-red color. In the beginning it was made with a metal base plate, later Bakelite ("plastic") was also used there. As with the Reichspost model, an NS 38 was used as the number switch, without a small dial. With many DDR-W 38 you can see a PVC spiral earphone cord, which is usually led into the rear center of the housing, but there are also examples with a cord inserted on the left side, as in the old Reichspost model. The only function-enhanced variant based on the Ost-W 38 is the "anteroom system 38", a simple boss / secretary system. Original DDR-W 38 are still available quite often today, even if they are often in poor condition. The successor from 1955 was first the W 55 (case of the W 38 with modified gearshift), then the rare W 38/58 (case of the W 38 with the gearshift of the W 58) and from 1958 came the newly designed W 58 - also with a black one Bakelite case, but in a completely different shape.
Due to their unmistakable appearance, the 36, W 38 and W 48 models are considered classics of industrial design today . Because they were once very widespread, they are still well known among the German population today. They simply stand for “the old telephone”.
Detailed technical descriptions and illustrations can be found in the articles for model 36 and W 48 .