Electronic Components

In the 1920's there were large numbers of radio kits on the market. These were popular as they were a lot cheaper than the ready built receivers, and attracted a lot of interest. Many enthusiasts built their own receivers, and magazines featured designs that anyone could build from the readily available bits and pieces. To cater for this rapidly growing market, A.J.S. sold many components separately. All of them carried the A.J.S. name and most of them were produced in Wolverhampton.
A.J.S. sold a range of chokes for various uses. The photograph opposite shows the first stage choke unit that was used with the detector valve in a receiver. It includes the grid capacitor and grid resistor, and sold for £1.

There was also a 2nd stage choke unit, for use in coupling stages of an audio amplifier. It also sold for £1. The choke was available on its own for 15s.0d.
A.J.S. produced a range of tuning coils for use with A.J.S. tuning capacitors. The coils were 3.5" in diameter and had a standard plug and socket fitting.
 


A list of available coils, and prices from 1926.

The coil number refers to the approximate wavelength (divided by ten) of the self-resonant frequency of the coil, so coil number 150 self-tunes to around 1,500 metres = 200 kHz. The inductance of the coil, assuming an internal capacitance of 10pF is 63mH. The coil below, a number 50, has an inductance of about 7mH.
 

The coils were wound from cotton insulated copper wire, and impregnated to make them moisture proof. This is an A.J.S. coil number 50.   This view of the coil shows the method of construction which produced a low capacitance winding.
A.J.S. patent variable low loss capacitors, were available in 4 values, with a knob and vernier adjustment. The prices were between 8s.6d., and 13s.6d.
A close-up view of an A.J.S. tuning capacitor.
A.J.S. fixed capacitors were available in a range of values. They had single hole fixing and were connected by solder tags. They sold for 1s..9d. and 2s.0d. each.
The inside of an A.J.S. fixed capacitor. It consists of copper foil plates and mica insulation. The assembly is clamped together by an external brass sleeve and impregnated with wax.
The inside of an A.J.S. resistor. It is made of some stiff carbonised material with copper connecting wires wrapped around the ends. The whole assembly has been immersed in wax.

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