In the 50’s and 60’s John T. Frye, W9EGV / Popular Electronics published a series of fiction stories called “The Carl and Jerry stories” – In each story the pair acquired new skills, got their ham radio licenses and used their knowledge of electronics to get out of a jam or solve a mystery – there isn’t a complete collection of all the stories that I know of, but there are some scans / text online. The stories are entertaining, fun and I can imagine how many engineers, scientists and Makers got their start from reading these wonderful tales – about & index.
In this story, Jerry built a long range sensor device, and also uses it to scare some kids from smoking…
“…I’m calibrating the temperature-reporting unit of our Tele-Tattletale,” Jerry explained with a teasing grin on his round face.
…opening the lid of the deep-freeze and lifting out a small wooden box with flat sides and rounded ends. The sides had large numbers painted on them, and one end was painted blue while the other was red. “This it is. I’ve been reading a lot about telemetering-or measuring at a distance-in connection with the satellites,” he explained as he gathered up the equipment and started back into the laboratory; “so I decided we ought to get a little experience with that sort of thing-even though we have to do it in a pretty crude way; “This little box,” he continued, “can be placed anywhere so that its small, self-contained transmitter is within range of that transceiver on the bench. We can determine four things by listening to the sig- nals from the Tele-Tattletale: (1) the temperature of the interior of the box; (2) the amount of light falling on both the red and blue endS; (3) if it is resting on side 1, 2, 3, or 4; and (4), what sounds are to be heard in its vicinity.”
“Interesting, if true,” Carl said doubt- fully.
“It’s true and really rather simple,” Jerry insisted, as he removed some screws and took off one side of the box. “I use the spiral bi-metal unit out of an advertising thermometer to turn this easily working variable resistor. The resistor determines the frequency of a transistorized oscillator. I’ve calibrated the oscillator’s frequency as a function of the surrounding temperature; so I know from the note it puts out how warm the box is. Photocells are mounted behind the openings in each end of the box. The resistance of each cell depends on the amount of light falling on it, and the cells are connected in twin oscillator circuits so that their varying resistances separately control the frequen- cies of the oscillators. By noting the frequencies of these oscillators, I can tell how much light is falling on either end of the box.” “ – Link.