Electrical Odds and ends from 1920

 

Federal Electric Engraver

     

 An old engraver complete with tool, original cables and brass working plate, I picked up at the Ringwood street auction. It looks about 1920 or slightly earlier and it works.

The equipment was made by Federal Products Corporation Providence, Rhode Island in the USA. This company which was founded in 1918 operates from 1144 Eddy St, Providence, RI 02905

A search reveals it's an Esterline Company and the R.I. address lists Mahr Federal Inc owned by Mahr GmbH of Germany who "merged" with the Rhode Island company in 1999.

 


WWI Army Morse Key

 The object below is a morse key which I've had for some time. Its made of brass on an ebonite base and I fixed it to a heavy iron baseplate for stability as I used to operate it via amateur radio. Somewhere I've got a circular ebonite plate which fits under the knob but other than that I think its complete and as used in the trenches in WW1.



WWII RAF Morse Key


 Early morse key made in Detroit USA

 This appears to be a "Strap" key with Sounder and may pre-date WW1. Looking at it closely you can see the end of the mounting plate furthest from the key has been sawn off and the end of the armature could have been longer. Maybe it started life as an electric bell used in an old telephone?
 
 


 

A "bug" key made by Eddystone

 This type of morse key automatically generates dots using a mechanical vibrating arrangement that can be adjusted for one's particular preferences.

Operation is completely different to a normal straight key, but surprisingly easy to master.

Left pressure sends a dash and right pressure on the paddle sends dots for as long as it is held over (at least up to about a dozen depending on how quickly the paddle is pushed over).


Old Dynamo 

 This hand cranked generator was designed in 1899 by Evershed and Vignoles and probably dates to between 1900 and 1910. It was originally fitted into a wooden box, hence the reason for the folding crank arm which tucked into an aperture in the box.

 

 This type of generator was used for several purposes, perhaps lighting, detonating explosives or measuring leakage resistance where you needed a higher voltage than that produced by a small battery. These leakage testers became to be known as "Meggers" and a generator was later combined with a meter in the same box.In fact you can find meggers using this principle dating from early Edwardian times to modern times. A megger with a serial number below about 50,000 will date to Edwardian times. In fact, the very earliest might have been made whilst Queen Victoria was on the throne.

Click here to see this particular version shown in the pictures is described in Patent GB189901758 (A)

I find it fascinating to see what was fitted into the top of the box. This is a spring loaded extension cable working on exactly the same principle as the mains cable devices on modern vacuum cleaners.
 
 On the left you can see eight sets of contacts each made from clamping a pair of brass disks to mate with circular contacts on the axial shaft. The brown coil assembly carries four separate windings connected so as to add together the voltage produced from each winding.
 
 
 
 

 Microphones

 The following microphones are generally used with transmitters rather than for hi-fi applications.

The first exhibit is a pair of the very popular Astatic D104 made in the USA. Both my examples have the T-UG8 stand which includes in its construction a transistor amplifier powered by a PP3 battery fitted into its base. Click either of the pictures below to see the specification.
 

 

 

 

 
 
 
 
 
 

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