Popular Electronics October 1963, V19 N4           Previous     Index     Next

CARL AND JERRY were well settled in their third year at Parvoo University. Tonight Jerry was alone in the room of the H-3 Residence Hall the boys shared, while Carl was over at the Sweet Shop on a Coke date with Jodi, the coed from Florida who was a friend of both boys. Through the open door came the sound of a language student across the hall strumming a guitar and singing softly in Spanish:

I like them all, I like them all,
I like them all in general;
But oh that blonde, but oh that blonde,
But oh that blonde I like the most!

"Hey, why the worried frown ?" Jerry asked. "You been quarreling with our honeysuckle friend?"

"Naw, nothing like that," Carl replied, "but I'm worried about her."

"What's wrong?"

"To put it bluntly, Jodi is afraid she's flipping her wig. She has a friend at that sorority house across the street, and every afternoon she's been parking her car behind H-3 and studying there while she waits for Thelma to get out of class. Yesterday while she was sitting there she got a kind of funny feeling. She couldn't concentrate on the integration of exponential functions she was doing, and she had this weird sensation of fear and anxiety. She was ready to panic when Thelma came, but after they drove away she started feeling better, and was O.K. until this afternoon.

"Today she parked there again. Exactly the same thing happened, only this time it was worse. She got more and more restless and nervous as she sat there trying to study until finally she clapped both hands over her ears and burst into tears. She said that seemed to help, because the feeling went away again.

"Now we both know this is not like Jodi, who is about as hysterical as a slide rule. She's really shook, though. I tried to kid her out of it by saying integrating exponential functions is enough to make a temporary lid-flipper out of anyone, but the girl is honestly afraid she's losing her mind."

"Has she seen a doctor?"

"Not yet, but she says she will if it happens again, even though she feels fine, has a good appetite, sleeps well, and so on. Oh yes: She was talking about this thing to Thelma in the sorority house, and one of Thelma's sorority sisters said that something very similar happened to her while she was standing on the sidewalk in back waiting for her date a couple of evenings ago. All at once she got very nervous and depressed and felt she just had to run away from there -even though this was a date with a BMOC she had worked very hard to get. Jodi doesn't put much stock in this, though. She says if you complain of anything from leprosy on down, someone is sure to say she had it first and worse."

"She still has her sense of humor; that's a good sign," Jerry commented with a grin. "Let me get this straight: this afternoon she clapped her hands over her ears and burst into tears. Right?"

"Yeah, but why?"

"I have a hunch that's so far out I don't want to discuss it yet. Do you think you can get Jodi to park there again tomorrow afternoon and give us a chance to do some investigating?"

"Sure," Carl said confidently. "She'd do anything to get this business cleared up."

"Fine, but don't ask her until I find out if I can borrow a piece of equipment from the high voltage lab. I'll know at lunch tomorrow."

THEY left it at that and got down to studying. At noon the next day Jerry gave the green light to Carl, who promptly went to see Jodi and arranged for her to study behind the residence hall that afternoon.

When Carl showed up behind the residence hall several minutes before Jodi was due to arrive, Jerry was sitting in the back seat of the boys' car which was parked parallel to the back of the residence hall. He was holding a strange-looking object in his lap.

"Hey, what kind of a crazy mixed-up weapon is that ?" Carl asked, taking it from Jerry's hands and examining it. "It has a rifle stock and a telescope sight, but no gun barrel. And what are these little round doohickeys mounted in a circle around the sight? Don't tell me this is a death-ray gun or I'll know you've flipped your lid!"

"O.K., so I won't tell you. Actually it's not a gun at all. It's an ultrasonic corona detector developed by the Westinghouse research labs to spot the high voltage corona leaks from transmission lines and other equipment. You know about corona. It happens whenever voltages are so high that some current escapes the conductor, especially at any sharp point or discontinuity, and radiates into space. Corona discharge wastes power and causes a lot of radio and TV interference, so power companies always try to locate and eliminate it. Finding one, though, is not always so easy. Sometimes it shows up as a blue glow in the dark with hissing, snapping noises, but in other cases it can't be seen or heard.

"One thing all coronas do is produce ultrasonic vibrations, and the detector takes advantage of this fact. Those twenty gadgets in a circle around the sight are ultrasonic transducers operating on about forty kilocycles and positioned so that the 'reception beam' is less than two degrees in width. Electrical pulses put out by the transducers are converted to the audio frequency range by transistor circuits and make static-like sounds in this little speaker near the rear of the sight when a corona discharge is being received. At a distance of seventy-five feet, this thing will pinpoint corona sources only a few inches apart on a high tension line. The telescope sight is lined up with the reception path of the transducers so that when sound from the speaker is maximum the cross-hairs of the 'scope are lined-up -right on the source of ultrasonic corona discharge--there's Jodi now," Jerry broke off. "Did you give her the little box and tell her to read the instructions inside ?"

"Sure, sure," Carl said impatiently, watching Jodi, who was looking very pretty in a bright red scarf, as she parked her smart little white convertible behind the residence hall. "I don't see why all this mystery is necessary. Nor do I see any connection between Jodi's moods and a corona discharge. There aren't even any high tension wires around here."

"You just keep your eye on Jodi and let me know if she opens that box and does anything with what's inside," Jerry instructed. He had slid down onto the floor of the car so that he could look through the telescope sight at the windows of the residence hall without being conspicuous.

"She must be getting that feeling again," Carl reported after a minute. "She's shaking her head and rubbing the back of her neck. She's opening the little box and taking something out of it. What was in it, earrings? She seems to be putting something on her ears."

Jerry was too busy to answer. Quickly but carefully he was aiming the sight of the corona detector at one open window after another of the residence hall. As he centered the crosshairs of the telescope on a second-floor window almost directly opposite where Jodi was parked, the little speaker of the instrument gave forth a loud crackling sound easily audible to Carl in the front seat. Moving the sight up or down or to the right or left of the window caused the sound to die out.

"I think this is the point where you're supposed to exclaim triumphantly, 'Aha!'," Carl offered with heavy sarcasm. "What do we do now?"

"We get out of here and into the building without attracting attention," Jerry said, laying the corona detector on the seat. The boys sauntered slowly to the door of the residence hall, but once inside, they dashed up the stairs to the second floor and ran down the hall to the door of the room from which the ultrasonic waves were coming. Cautiously Jerry tried the knob. The door was locked.

"We've got to get in there without arousing their suspicions, and we've gotta do it fast," Jerry whispered. "Do you know the name of either of the guys in this room?"

"Yeah. Both are freshmen, and one of them is Victor Brown," Carl whispered back. "I met him at the radio store last week. He's kind of a hi-fi nut."

"Fine! Good old Victor's going to get a telephone call in a few seconds. When he comes out to answer it, you go in -fast. I'll be right behind you."

JERRY went to the telephone booths in the hall and dialed a number. He spoke into the transmitter, and almost immediately Carl heard the buzzer inside the room with the locked door signaling a telephone call for one of the occupants. Tbe door was unlocked, and a tall, thin, weak-chinned boy stepped into the hall. Before he could close the door behind him, Carl rudely pushed him to one side and stepped into the room. Jerry was right on his heels, shoving Victor ahead of him.

Peering out the window across the room was a big hulking youth with a bristling crew-cut. On a table beside him was a large audio amplifier, and feeding into it was an instrument Carl recognized at a glance as an audio oscillator. A wire ran from the amplifier to an extra-heavy-duty speaker unit attached to the rear of a long, narrow-throated horn aimed out the window directly at Jodi in her convertible. Glowing pilot lamps on both oscillator and amplifier showed they were operating, but not a sound was heard coming from the speaker.

The big youth wheeled around at the sound of scuffling and took a threatening step or two toward the door until he sized up Carl's brawny frame and saw Jerry behind him. Jerry ran over and turned off the oscillator, but not before he noticed that it was operating around 35 kc.

"What do you two think you're doing?" he asked the two freshmen sternly.

"We're just having a little fun," Victor answered the upperclassman nervously. "Joe's dad used that king-sized tweeter for some ultrasonic testing in his factory. We were playing around with it on this hundred-watt hi-fi amplifier and decided to see what happened when we turned the beamed output on that girl down there in the car. It seems to kind of bug her."

"Sounds just like a couple of stupid freshmen," Carl commented. "You may be injuring the girl. High-powered ultrasonic waves shouldn't be fooled with. And don't lie to us. This isn't the first time you've used that thing on human beings."

"We did try it two or three other times," Victor confessed, "but we sure didn't want to hurt anyone. Are you going to turn us in?"

Carl and Jerry exchanged glances. The minds of both went back to their first week in Parvoo and the night they wired the mailbox for sound and were unlucky enough to have the president of the university for their first victim. "Not if you take that thing apart right now and never use it again," Carl said gruffly.

The apparatus was already being dismantled as Carl and Jerry left.

THE BOYS joined Jodi and Thelma, a vivacious red-head, and the four of them went to a drive-in in Jodi's car to get something to eat and to discuss the adventure.

"I've got a friend who worked in the lab of a radio manufacturer during the war," Jerry explained. "He told me about the lab jokers horsing around with high-powered ultrasonic waves. They pointed the horn through the door of the lab at a girl secretary some seventy-five feet away. She acted just like you, Jodi. She got nervous and fidgety and finally broke into tears. Next they turned the beam on an expert man typist. He didn't cry, but he began making one typing error after another .

" All this came back when Carl told me what happened to you. I figure the sound waves affect the ears, even though they don't register as sound. That's why I sent the ear plugs and asked you to use them when you began to feel the ultrasonic vibrations. Carl and I had to have some time to locate the ultrasonic source if there was any, but we didn't want you going out of your ever-loving mind while we were doing it."

"I'm sure glad it wasn't all just in my mind!" Jodi exclaimed. "I just love this little old ultrasonic detector," she drawled as she pressed the gun stock against her cheek.

"That name seems a little common for this gadget," Carl said. "I'd rather think of it as a high-toned Hawkshaw!" -30-

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