How to Make a Receiving Set for $5.00 or less

The Radio Amateur's Hand Book, by A. Frederick Collins is part of HackerNoon’s Book Blog Post series. You can jump to any chapter in this book here: [LINK TO TABLE OF LINK]. Chapter XX: How to Make a Receiving Set for $5.00 or less

XX. HOW TO MAKE A RECEIVING SET FOR $5.00 OR LESS

In the chapters on Receptors you have been told how to build up high-grade sets. But there are thousands of boys, and, probably, not a few men, who cannot afford to invest $25.00, more or less, in a receiving set and would like to experiment in a small way.

The following set is inexpensive, and with this cheap, little portable receptor you can get the Morse code from stations a hundred miles distant and messages and music from broadcasting stations if you do not live too far away from them. All you need for this set are: (1) a crystal detector, (2) a tuning coil and (3) an earphone. You can make a crystal detector out of a couple of binding posts, a bit of galena and a piece of brass wire, or, better, you can buy one all ready to use for 50 cents.

Photograph unavailableWireless Receptor, the size of a Safety Match Box. A Youthful Genius in the person of Kenneth R. Hinman, Who is only twelve years old, has made a Wireless Receiving Set that fits neatly into a Safety Match Box. With this Instrument and a Pair of Ordinary Receivers, He is able to catch not only Code Messages but the regular Broadcasting Programs from Stations Twenty and Thirty Miles Distant.

The Crystal Detector.--This is known as the Rasco baby detector and it is made and sold by the Radio Specialty Company, 96 Park Place, New York City. It is shown in Fig. 96. The base is made of black composition and on it is mounted a standard in which a rod slides and on one end of this there is fixed a hard rubber adjusting knob while the other end carries a thin piece of phosphor-bronze wire, called a cat-whisker To secure the galena crystal in the cup you simply unscrew the knurled cap, place it in the cavity of the post and screw the cap back on again. The free end of the cat-whisker wire is then adjusted so that it will rest lightly on the exposed part of the galena.

The Tuning Coil.--You will have to make this tuning coil, which you can do at a cost of less than $1.00, as the cheapest tuning coil you can buy costs at least $3.00, and we need the rest of our $5.00 to invest in the earphone. Get a cardboard tube, such as is used for mailing purposes, 2 inches in diameter and 3 inches long, see A in Fig. 97. Now wind on 250 turns of No. 40 Brown and Sharpe gauge plain enameled magnet wire. You can use No. 40 double cotton covered magnet wire, in which case you will have to shellac the tube and the wire after you get it on.

As you wind on the wire take off a tap at every 15th turn, that is, scrape the wire and solder on a piece about 7 inches long, as shown in Fig. 99; and do this until you have 6 taps taken off. Instead of leaving the wires outside of the tube bring them to the inside of it and then out through one of the open ends. Now buy a round wood-base switch with 7 contact points on it as shown at B in Fig. 97. This will cost you 25 or 50 cents.

The Headphone.--An ordinary Bell telephone receiver is of small use for wireless work as it is wound to too low a resistance and the diaphragm is much too thick. If you happen to have a Bell phone you can rewind it with No. 40 single covered silk magnet wire, or enameled wire of the same size, when its sensitivity will be very greatly improved. Then you must get a thin diaphragm and this should not be enameled, as this tends to dampen the vibrations of it. You can get a diaphragm of the right kind for 5 cents.

The better way, though, is to buy an earphone made especially for wireless work. You can get one wound to 1000 ohms resistance for $1.75 and this price includes a cord. [Footnote: This is Mesco, No. 470 wireless phone. Sold by the Manhattan Electrical Supply Co., Park Place, N.Y.C.] For $1.00 extra you can get a head-band for it, and then your phone will look like the one pictured in Fig. 98

How to Mount the Parts.--Now mount the coil on a wood base, 1/2 or 1 inch thick, 3-1/2 inches wide and 5-1/2 inches long, and then connect one end of the coil to one of the end points on the switch, and connect each succeeding tap to one of the switch points, as shown schematically in Fig. 99 and diagrammatically in Fig. 100. This done, screw the switch down to the base. Finally screw the detector to the base and screw two binding posts in front of the coil. These are for the earphone.

The Condenser.--You do not have to connect a condenser across the earphone but if you do you will improve the receiving qualities of the receptor.

How to Connect Up the Receptor.--Now connect up all the parts as shown in Figs. 99 and 100, then connect the leading-in wire of the aerial with the lever of the switch; and connect the free end of the tuning coil with the ground. If you have no aerial wire try hooking it up to a rain pipe that is not grounded or the steel frame of an umbrella. For a ground you can use a water pipe, an iron pipe driven into the ground, or a hydrant. Put on your headphone, adjust the detector and move the lever over the switch contacts until it is in adjustment and then, if all your connections are properly made, you should be able to pick up messages.

Photograph unavailable--Wireless Set made into a Ring, designed by Alfred G. Rinehart, of Elizabeth, New Jersey. This little Receptor is a Practical Set; it will receive Messages, Concerts, etc., Measures 1" by 5/8" by 7/8". An ordinary Umbrella is used as an Aerial.

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Collins, A. Frederick. 2002. The Radio Amateur's Hand Book. Urbana, Illinois: Project Gutenberg. Retrieved April 2022, from https://www.gutenberg.org/files/6934/6934-h/6934-h.htm#chap20

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