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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. How to Mount the Parts. This done, screw the switch down to the base.
He plugged in his earphone and called. "Barby!" There was no reply. His lips set grimly. No use wasting time here. He ran from the house, hearing the sound of the Sky Wagon as Scotty warmed it up. Joe Blake was not in sight. Rick hurried into the lab and found him watching Professor Morrison who was checking some calculations on the lab's small computing machine.
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: a crystal detector, a tuning coil and an earphone.
In 1921 when he was in the 4th form at school he had bought two kits of parts from France and put them together with the help of his fellow-student George Grabinger. The kit consisted of a bright emitter triode in an oscillating circuit. The heater supply was a 4 volt accumulator, and a dozen or so dry cells, with an earphone in series, supplied the anode voltage.
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.
Inside the newspaper office, he took out his scout knife and carefully slit the top of one cereal box. He removed the little radio from his pocket, unplugged the earphone, and put the radio on top of the cereal. He borrowed cellophane tape and taped the box shut, then he put both boxes of cereal back in the bag with the sugar on top. He handed the bag to Jerry. "Do your stuff."
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. Now wind on 250 turns of No. 40 Brown and Sharpe gauge plain enameled magnet wire.
For a long moment he listened, then held out the earphone with a broad grin. "Anyone care to listen?" Everyone did. They took turns, with each application of the phone to an ear accompanied by expressions of astonishment. Barby looked at her brother with new respect. "It's just fantastic! How on earth does it work?" Dr. Miller chuckled. "I'm sure you don't want a full course in electronics, Barby.
We'll find that someone has been pulling a very cute confidence game, bringing clients here by night, showing them the radioactivity by letting them hear the clicks in the earphone of a counter, probably and then selling them either shares in a mine or pieces of property." "And using the ghost to scare the townspeople away so there would be no interference," Rick finished.
Some blades have no such spots. Others have many. Rick was beginning to think that he had one of the no-spot kind, or that the whole idea was wrong, when he heard what he thought was a voice. He hastily concentrated on the spot, and in a few seconds music flooded into the earphone. He had caught a disk jockey in the process of introducing a record.
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