Author Topic: Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)  (Read 2627 times)

Offline dsk

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Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)
« on: January 08, 2015, 04:16:40 AM »

unbeldi

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Re: Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)
« Reply #1 on: January 08, 2015, 09:00:49 AM »
Can you tell us some history about it?
I would say late 1940s early 1950, made in Sweden. Design seems to be based on the late 40s versions of the Ericsson 1931 line.  Is it painted or ivory plastics?

Offline dsk

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Re: Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)
« Reply #2 on: January 08, 2015, 11:31:58 AM »
Make: Elektrisk Bureau, Oslo Norway.
Design: Johan Christian Bjerknes
Introduced in black 1953, Ivory made 1953-1966 in a number of 28 900
Claimed to be the first phone made with thermoplastic (case, dial and handset)
Combined wall/table top
Dynamic receiver (moving coil).
Approx. REN load: 1.2

unbeldi

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Re: Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)
« Reply #3 on: January 08, 2015, 11:39:37 AM »
I noticed that the dial can be rotated 180 degrees so the phone can be mounted on the wall, and the cradle can hold the handset in that position too.

unbeldi

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Re: Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)
« Reply #4 on: January 08, 2015, 12:04:16 PM »
Make: Elektrisk Bureau, Oslo Norway.
Design: Johan Christian Bjerknes
Introduced in black 1953, Ivory made 1953-1966 in a number of 28 900
Claimed to be the first phone made with thermoplastic (case, dial and handset)
Combined wall/table top
Dynamic receiver (moving coil).
Approx. REN load: 1.2

The first Norwegian phone made from thermoplastics?
Thermoplastic telephones were already produced in the 1930s.

The histories of Elektrisk Bureau, Telegrafverket (Sweden), Telegrafverket (Norway), and Ericsson (and others) appear to be intertwined to a great deal, so that Ericsson's patents were apparently available to any of them. The principal designers of the housings and even the internals indeed seem to be of Norwegian heritage in EB.  The looks of this seems to be in the middle somewhere between the DBH and the Dialog.
« Last Edit: January 08, 2015, 12:13:25 PM by unbeldi »

Offline dsk

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Re: Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)
« Reply #5 on: January 08, 2015, 03:07:42 PM »
It looks like telephone designs, and circuits are pretty close to coping each other forth and back trough history.
The design of this phone has been promoted as a unique Norwegian design, we know better today. It is definitely inspired by others.

The universal cradle, and position changing of the dial are used before. The circuitry are an optimized/improved version of whats made back in 1930 by  Standard Electric (W.E. Europe) not to different from the one in a W.E. 302.  A classic ringer (old fashioned), but more sensitive to weak ringing signals than the regular ringer in a 302 or 500. (2800 ohms and 1 microfarad measured to 1.2 REN by me).

This telephone design was the only available from the monopoly from 1953 to 1967. It was in a time where you might have to wait several years from ordering to getting a phone (and line).  We had one, and pretty often we got calls to our neighbors, or they came to borrow the phone.  It was extremely expensive to use.  In hence to the index of 1967, about $1 pr period of 3 minutes. (local calls) Today I may call from $0.0495 pr minute to a cellphone all over our country, or $0.0198 pr minute to a regular phone.   

dsk
« Last Edit: January 08, 2015, 03:10:52 PM by dsk »

Offline 19and41

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Re: Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)
« Reply #6 on: January 08, 2015, 03:13:35 PM »
When I took plastics as a class in high school, the instructor drummed into us that there were two types of thermally worked plastics.  They were the thermoset plastics that are compression molded from pulverized material put into a mold and heated to fuse it into a finished item.  Bakelite is the most common of that type, in use from the first decade of the 20th century.  Then there are the thermoplastic resins that are preheated, become plastic and are customarily injected into their mold and are cooled to solidify them  Those are the plastics that are referred to as "soft" plastics in this forum.  That may be what is being referred to in the claim involving thermoplastics.
"Any sufficiently advanced technology is indistinguishable from magic."
Arthur C. Clarke

unbeldi

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Re: Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)
« Reply #7 on: January 08, 2015, 04:27:37 PM »
When I took plastics as a class in high school, the instructor drummed into us that there were two types of thermally worked plastics.  They were the thermoset plastics that are compression molded from pulverized material put into a mold and heated to fuse it into a finished item.  Bakelite is the most common of that type, in use from the first decade of the 20th century.  Then there are the thermoplastic resins that are preheated, become plastic and are customarily injected into their mold and are cooled to solidify them  Those are the plastics that are referred to as "soft" plastics in this forum.  That may be what is being referred to in the claim involving thermoplastics.

Your distinction between the major two classes of plastics, thermosets and thermoplastics, is correct.  However, the term resin is usually reserved for the starting material for making the thermosets. It is non-polymerized material before any reaction has occurred.  The thermoplastics are already chemically finished polymers when they are used for making a product and are only reshaped by heating and injection molding.

What is referred to as soft plastic here is rather nebulous, as it is used for only the thermoplastics used for the 500 sets in the 1950s and their contemporaries by other manufacturers that look similar to the 500 sets.  I don't think we have any solid documentation what kind of plastics other manufacturers actually used and I haven't found a single chemical analysis of any. The thermoplastic material of the 302 sets is extremely similar, yet not treated with that term, it seems.  And why is it called "soft"? compared to what else? Looking at plastic hardness test charts, many plastic types come in broad hardness ranges. Bakelite, or more generally phenol-formaldehyde polymers, can be harder or softer depending on composition and molding specifics.

By my readings, the first Bakelite housings may have been produced by Automatic Electric in the 1920s. Kellogg probably wasn't much further behind in time. However, AE's sets still had metal parts for the cradle.  Ericsson's DBH 1931 phone is famously proclaimed to be the first 100% Bakelite phone, the "Bakelite Phone".  Bakelite phones proliferated during the 30s, AE, Kellogg, ...
Even Western Electric produced development versions in Bakelite of the 302 starting in 1931 or 2 and a Bakelite wall phone based on the same technology. Sometime in the mid to late 1930s AE produced colored phones made from cellulose acetate, a thermoplastic that had been known for a long time, but was first commercialized by Eastman in the late 20s, and trademarked around 1930 as Tenite.  In Europe, I believe, urea-formaldehyde thermosets were produced for colored phones also in the 1930s.
« Last Edit: January 08, 2015, 04:29:32 PM by unbeldi »

Offline dsk

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Re: Telegrafverket normal dial starts at nok 75 ($ 10) (not mine)
« Reply #8 on: January 08, 2015, 04:52:08 PM »
The term thermoplastic are not exact, but believe the common description will be a type who may be granulated, and heated up for reuse and molding several times, the opposite will be those who are hardened, and will not melt to a liquid by heating.

dsk