CHAPTER XI
CLEVER THINKING
The radio boys were at Bob's house on the dot, all but Jimmy, who to his great disgust had to do some work for his father, and so could not come.
"I suppose we'll have to try to get along someway without his valuable assistance," said Herb. "When he told me he couldn't get here this afternoon he certainly felt sore about it."
"I guess I know how he feels, all right," said Joe. "It would pretty near break his heart not to be able to work on this radio stuff now. I'm crazy for the time to come when we can pick our first message or music out of the air."
"I guess you're no more anxious for that to happen than we are," said
Bob. "Let's go downstairs and see what we can do."
They all made their way to Bob's workroom in the basement, where they found the core well dried and the wire as firmly set on it as the most particular workman could desire.
"Good enough!" exclaimed Bob, examining the core with loving pride. "We'll get this set up in a jiffy, and then we can make the condenser."
Working together, the boys soon had two square blocks sawn out as end pieces, and they centered the core on these and screwed it fast. Then they drilled holes in the two upper corners of the square end pieces to fit two brass rods they had bought at the hardware store. These rods carried each a small sliding spring, or contact, which rubbed along the length of the tuning coil, one on each side. After they had bolted the brass rods securely in place, the coil was ready for use, except that the boys had first to scrape off the insulating enamel in the path of the sliding contacts, so that they could reach the copper coils. A sharp pen knife soon effected this, and the boys found themselves possessed of a neat, substantial tuning coil, at a cost of only a fraction of what it would have been if they had had to buy a coil already made. And in addition they had the satisfaction that comes of a good job well done, which more than compensated them for the labor involved.
"That begins to look like business," exulted Joe. "We'll be putting
Mr. Edison out of business pretty soon."
"Yes, it's lucky he can't see that tuning coil," laughed Bob, "he'd be looking up the want ads in the papers, sure."
"Oh, that coil won't be a patch on the condenser we're going to make," declared Herb.
"I know we've got to have a condenser, but I'm blessed if I really understand what it is for," said Joe. "I know the doctor told us about it, but I guess I didn't get a very clear idea of what it was all about."
"I'm not very clear on it either," admitted Bob. "But from what he said and what I've read, it seems to be a sort of equalizer, for the electric current, storing it up when it's strong and giving it out when it's weak. It prevents the current getting too strong at times and burning something out."
"That's the way I understood it, too," said Herb. "And Dr. Dale said that in the larger sets they have what they call a variable condenser, so that they can get more or less damping action according to the strength of the incoming current waves."
"I guess I get the idea," said Joe. "But it's a pretty complicated thing when you first tackle it, isn't it?"
"Yes, but it's just like almost anything else, probably—it's easy when you know how," said Bob.
"It tells here how to make the condenser," said Herb, who had been looking over an instruction book that the boys had bought. "But it says the best thing to use for the plates is tinfoil. Now, where are we going to get the tinfoil from, I'd like to know!"
"If you want to know real badly, I'll tell you," said Bob. "Right out of that box over in the corner. Just wait a minute and I'll show you."
Bob stepped swiftly over to the box in question and produced a big ball of tinfoil, composed of separate sheets tightly packed together.
"When I was a kid I used to collect this stuff and sell it to the junkman," he said. "This ball never got big enough for that, and I forgot all about it until a few days ago when I happened to come across it and thought that it would be just the thing for us to use now. We can easily peel off all the sheets we need, I guess. Some of them are damaged, but there are enough whole ones to do our trick."
"Gee, that's fine!" said Joe. "Pry off some, Bob, and let's see if it will serve."
With his knife Bob pried away at likely looking places, and soon had several large sheets off. These, when smoothed out, looked good enough for any purpose.
"How many does the book say we'll need, Herb?" asked Bob.
"It says eight or ten, each one about four inches square," answered
Herb. "And it says they have to be separated by paraffined paper.
How are we going to get hold of some of that?"
"Paraffine wax is what they use to seal fruit jars," said Joe.
"We ought to be able to get some of that easy enough."
"Mother had a big cake of it last summer!" cried Bob. "Maybe she has some of it left. Wait here and I'll ask her," and he dashed up the stairs three steps at a time.
In a few minutes he returned, having obtained not only the wax but a small sauce pan in which to melt it.
"I thought I'd bring this along, so as to have it," he said; "but it's so near supper time that I don't think we'll have a chance to do much more—right now, anyway. What do you say if we knock off now and do some more work this evening after supper?"
"Gee, I never thought it was that late," said Herb. "If Jimmy had been here, I suppose he would have been talking about supper for the last hour or so, and we'd have known what time it was."
"Well, I'll be here for one," said Joe, "and I'll stop at Jimmy's house on the way home and tell him to get around, too."
"I'll come too," said Herb. "And, Joe, while you're about it, tell Jimmy to be sure and bring another chunk of chocolate, only bigger than the one he had last night."
"I'll be sure to mention that," grinned Joe. "But I don't think he'll do it, just the same."
Bob went upstairs with them, and Herb and Joe went away together, after promising to come back as soon after supper as possible. After they had gone, Bob could not resist the temptation to go down and gaze with an approving eye on the shiny new tuner they had made, and dream of the many wonderful sounds that would soon come drifting in through that gleaming bit of mechanism.