An Ejector for any Circuit

Radio Record, Volume IV, Issue 34, 6 March 1931, Page 17

An Ejector for any Circuit

Some Amendments

A SLIGHT error occurred in the text of the original description of this very efficient wave trap and, although it was apparent to those who were conversant with circuits, it probably gave trouble to others. The corrected description should read :- "On a good cardboard former which made from 2hin, to 2gin, in diameter and about 3in. long, fix with glue. matebhsticks without their heads. These should be from fin. to fin. apart. Over this wind on closely and tightly about forty feet of 22 DCC. copper wire.,. This amounts to roughly 50 turns. Leave some 6in. slack at each end after anchoring the ends to the holes in’ the former as shown. These ends will ultimately connect with the moving condenser marked "9 in the diagram. This is the secondary coil. Over the centre of «the coil fix a band of tissue paper about an-inch broad, and over this wind ten turns of 18 DCO. wire in the same direction as the secondary was wound. Anchor these turns as shown-in the diagram and leave about 6in, slack at the end. This is the primary , coil marked "P" in the diagram. One endconnects with the aerial and the’ other with the terminal of the ser. The condenser should be"fastened to a formica panel, the coils being placed in: an oblique position to it when completed. Efficient soldering must be

effected wherever possible, even to the set. terminal if the ejector is to be a permanent connection. ‘In tuning, use both dials until signals are at the loudest. The interfering signal can be then trapped out; or again, trap out the interfering signals and tune in those desired with the dial on the set. A little practice may be neeessary as this apparatus, if ‘well made, is somewhat critical in us‘ng. By running X through a crystal detector, thence through phones and on ‘to connection Y, or, better still, con-

necting X and ¥ to a double point switch and wiring them as just said, reception can be had by: either valve or erystal receiver at will.: In this case the arrow point goes to earth. The trap will also smooth out rough signals, reduce static, and it also has improved both tonal and tuning qualities often enough. It does not diminish volume and the writer knows quite well it will solve many of the complaints from listeners that appear from time to time. This cireuit does not assist short-wave reception. -For crystal work connect arrow point to earth.