A pair of ancient Crystal Sets

 The first example is an early crystal set which might pre-date broadcasts from the BBC in 1923. The case is very amateurish and the front panel with its studded switch are probably WW1 surplus. The crystal which would fit in the brass socket was missing when I got this set. The labels are riveted in place, which to me means the set was probably made commercially and not home-constructed.
 

 Under the front panel is a very basic tuning coil originally clamped between the strips of wood. The soldering looks a bit suspect and the wire from the switch wiper is missing. I wonder if this missing wire resulted in the set being a disappointment to its owner?
 
 Here's the detector, or at least it would be if the crystal was in place. I'll fit one sometime and sort out the wiring then see if it works. The method of operation was simple. With headphones clamped around your ears you connected a long wire aerial then carefully placed the cat's whisker in contact with the crystal. A proper cat's whisker may have been a neatly coiled wire having some springness so it would stay in contact with the crystal but this one is a bit rudimentary. A crystal has various indentations and cavities which may or may not provide rectification of radio signals. The aim is to fiddle around until one heard a tiny crackling noise, then adjust the coil switch for best volume of the local medium or long wave station. These sets were broad band receivers with very poor selectivity and usually one could hear most broadcast stations at the same time. By adjusting the switch you could hopefully tune the station to which you wanted to listen without too much interference from others.
 

 I decided to find a crystal and to fit it in place, a really fiddly job.
 

 Here's a second example, although in even poorer condition. It came from a workshop belonging to a late friend and was tucked away at the back of a drawer, the box containing a set of old TV valves. It's a bit of a puzzle because the ancient box is a fraction too narrow for the panel. It's seems someone had it in mind to mate up the panel and the box, then decided it was too difficult (breaking off part of the box when forcing the panel into grooves) and put it away for inspiration, which clearly never happened. We'll now never know. A couple of points. Firstly the parts look very similar to those used in the first example shown above and are almost certainly more WW1 surplus. Secondly, if you look hard you can see the the word "TELEPHONES" is printed on the panel, also you can see on the picture the labelling "AERIAL" and "EARTH" printed against the two terminals on the right. The style means the set was probably sold commercially and, from what remains, may well date before 1923. The socket carrying the three screws is for a crystal, but this and the post carrying the cat's whisker is missing.

 

 

 Above is a view showing the underside of the front panel, missing of course the wiring and the coil which would have been much like the one in the first set on this page. Below a closer view of the label "telephones" which, because it was printed, means that the set was not home-constructed. These early crystal sets all used much the same circuitry and parts. Because of the extremely high prices of parts a tuning condenser was rarely used. Tuning relied on the self capacity of a large coil which had lots of tappings which enabled a set to tune approximately from around 300 metres to 2000 metres. The manufacture of coils was often sub-contracted by the setmaker to schoolboys for a few pennies for each coil.

Nowadays one cannot get one of these early sets going in the way it was intended to work unless you have a pair of high impedance headphones.

 

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