Illinois Junior Academy of Science - Yearbook (Urbana, IL)

Page 61 text:

transistor operation. The transistor radio's current is 30 microamps, and the voltage is 1.5 volts. This is .000045 watts. The three-tube radio is the most sensitive and selective. It can, through a series of four coils and two 365 mmfd. variable capacitors, separate very strong local stations. Also, with an antenna of fifty feet, ,a 1000 watt station was re- ceived forty miles away. A 50,000 watt station 100 miles away came in with fair volume. Three tubes are employed. They are a 35Z5 rectifier toctal basel, a 12A17 high-mu twin triode as detector and first AF amplifier C9 pin miniature? and a 50C5 beam power tube i7 pin miniaturel. This radio produces about 80,000 times the output of the one-transistor radio. The plate voltage is 120 volts, and the plate current is 30 milliamps. Power is 3.6 watts. My project has been a valuable tool in learning and verifying the laws of electronics. Theory, Design, and Application ot a Single Sicle- band-Suppressed Carrier Generator STEPHEN C. BECK Arlington High School Arlington Heights Sponsor: Morris J. Pumphrey The purpose of my project was to demonstrate one of the methods of radio communications that could help to ease this problem of overcrowded frequencies. A single sideband-suppressed carrier radio signal oc- cupies only one-half the frequency space of conventional radio signals. The most widely used mode of communications by voice is amplitude modulation, or AM. Single sideband, which is usually shortened to SSB, offers many advantages over AM. There is a power gain with SSB over a similar AM transmitter. Increased readability and less interference with other signals are also benefits of SSB. Clearly single sideband is a much more efficient mode. There are two common methods of generating a side- band signal, the filter method and the phasing method. The model generator in my project is a phasing generator. By using special electronic circuits, the phase, or the frequency relationship, of two radio signals can be adjusted to give just one sideband. Since the sideband carries the informa- tion in the radio signal, it is the only part of the signal worth transmitting. The resulting low-level output of the generator is then amplified in conventional manner. Since there is output only with modulation by a voice, the ampli- fier is only doing full work part of the time. This accounts for the increased efficiency of SSB over AM. My procedure began with drawing up a list of desirable features and minimum specifications. Simplicity was also stressed. No circuits that I had seen in various magazines and books were acceptable. I did want to design my ovsm circuit, and this seemed the opportunity. After gathering all available circuits of phasing generators, I looked them over to get an idea of what I would have to include in my design. The primary reason that I didn't use any of these circuits is that they were too complex. Careful design gave me a circuit that looked as if it would meet my specifica- tions. The final model came after three trials of the original circuit, each trial followed by several modifications and changes in the design and component values. All of the work in designing was written up, and a demonstration pre- pared of single sideband. Construction and Applications ot a Binary Com- puter JOHN R. Kmscl-INER lay Stanley Field School Northbrook Sponsor: Mrs. Rosemary Vincent e i V . i g ' as E lei 2 .Ei x 1 V l '1.5' l V lllhh llllill-Sl'l-flylt MIN XRX t'0l'N' This project has involved the study of mathematics and electronics, and how electrical circuits can perform mathe- matical operations. I have studied the different number bases, particularly base two, or as it is often called, the Binary System, which is used in computers. I also studied about a number of different binary codes which are used in computers for special purposes. First a simple mechanical counter was constructed to understand the binary system. Then I experimented with transistors and transistor circuits to build an electrical cir- cuit which would count in the minary system. Next a relaxation oscillator was built to take the place of the telephone dial I had used during my early experimen- tation. This provided automatic pulses for my counter, and the rate of these pulses could be changed by varying resis- tor and capacitor values. As a further improvement I have recorded pulses from the oscillator on magnetic tape, as pulse groups, for future use. In order to investigate useful purposes for my high speed counter, I have constructed many additional circuits. I have been able to successfully measure time, speed, dis- tance, and quantity, with good accuracy. Mathematical op- erations such as addition, subtraction, multiplication, and division, can be performed by using my counter and addi- tional circuits, which include a tape recorder for storing electromagnetic pulses, an amplifier-relay circuit for con- trolling these pulses, and an additional flipflop circuit for switching purposes. An Automatic Missile Checkout System DAVID MEYERS William J. Bogen High School Chicago The p1.u'pose of this project is to develop an automatic, programable, computer-controlled system to test the con- trolled system to test the condition of various sub-systems onboard a missle prior to launch. Program information is fed into the computer by a standard perforated tape. The instructions, read by the tape reader set up the equipment for each test and print out on the page printer the nature of the test being con- ducted. The computer then activates the needed measuring cir- cuitry and transmits the test results to the magnetic re- corder control system. This system evaluates these results and advances the tape to the position corresponding to the

Page 60 text:

The Secrets Behind Color Television Picture Tubes M. GALVIN EEERET5 BEHIND r i. w Pn:'ruRr: rum: . El '- 53 The main parts of a color picture tube are the glass bottle envelope, which is composed of a faceplate, a funnel and a neck: the shadow mask, and a tri-element gun. ENVELOPE - The envelope is the glass bottle con- tainer of the working parts. FACEPLATE - The glass faceplate is the screen of the color television set. On it are placed phosphor dots that when excited by electrons, give off color, in this case green, blue and red. The reason these colors are used is that they are the primary colors of light. Phosphor is a photosensitive chemical which when excited by electrons will give off color. FUNNEL - The funnel is the middle of the glass bottle envelope. It is like an ice-cream cone in shape. NECK - The neck is the housing for the electron gun. The gun is inserted into the neck. SHADOW MASK -- The shadow mask has 400,000 holes etched into it. It is like the end of a gun barrel for the stream of electrons: it' guides the electrons to the certain dot whether green, blue or red. ELECTRON GUN - The electron gun is three guns within itself. One gun to excite the green dots, one to excite the blue, one to excite the red. Each gun is geometrically set to shoot and excite only its given dots. In this case if we turn on the green gun, it only lights up the green dots with the help of the shadow mask. Each gun scans the face- plate through 525 steps or lines 30 times a second. Mark 002 Printing Computer MARK enrmes gay Infant Jesus of Prague School Flossmoor Sponsor: Sister M. Rosaire, O.P. The Mark 002 is a digital computer capable of receiving decimal numerals from a card reader and a typewriter. Thesf: then convert the decimal numeral to binary, or base 2, nu- merals. This system can be used by the Mark 002 because of the twoness property of electronic switches - on and off. But, what does the Mark 002 do? By accepting two or more numeral, providing that you supply an add command after each, the Mark 002 can add those numbers using a serial adder circuit. The total num- ber of relays in all of the combined adders is 21 which are needed to add up to 2' or 31. In order to get the final binary sum printed out on the typewriter, the I key must be pushed. This activates a 40-step stepping relay which prints out the binary answer preceded by the expression would you believe. By pushing the reset button, all adders in the on position are returned to the off position, and the stepper will reset to the point of origin. Program panels with plug-in wires are used in order that anyone may pro- gram the Mark 002 in whichever way best suits his means. Being more than just a calculator, the Mark 002 can be considered a computer. It fulfills all of the qualifications of a computer, for it has input, control, computing, memory, and output units. And together with its special program- ming techniques, the Mark 002 can easily be adapted to many applications -- from binary adder to a control and output unit for many large-scale computers. 5 A M Radio oAvl-D M. BEAMS lay Thomas Jefferson Junior High School Springfield Sponsor: Mr. Donald Roderick The aim of my project was to start learning about radio and electronics in general. In a nine-month span, I built one transmitter, two diode radios, one transistor radio, and one grid-leak detector with two Class-A amplifiers. All of these were TRF receivers. The two diode receivers were counterparts of each other. One uses a IN34 diode as a detector. The other uses a IT4 pentode connected as a diode for a detector. The two-transistor transmitter uses one transistor as an oscillator. Feedback to sustain oscillation is provided by a disc capacitor. The output frequency is determined by a 220 mmfd. disc capacitor and L-1, a tapped transistor radio coil. The second transistor varies the voltage applied to the einitter of the oscillator and thereby modulates the r.f. signa. The r.f. output of this transmitter can be observed on an oscilloscope by connecting wires from the antenna and ground sides of L-1 to the vertical deflection plates of the oscilloscope. The transistor radio uses a 365 mmfd. variable capacitor and a tapped transistor coil for tuning, and one transistor as a detector. Two S.P.S.T. slide switches elect one or two-

Page 62 text:

value of the measurement. Here, the magnetic tape trans- fers the test results to the page printer where print out occurs. The system then resets and is ready to accept the next command. At the conclusion of the testing cycle a launch sequencer is activated which starts a master clock. This clock displays in digital form the time until launch. At T minus zero a simulated missle is fired and the roar of the take-off can be heard. Also built into the display board is a switching system which automatically demonstrates the operation of the mis- sile system by means of a lighted diagram. Tic-Tac-Toe Computer JOHN oRwlN lay Forest Road School LaGrange Park Sponsor: Mr. J. David Johnson The objective of this project was to design a computer to play the game of tic-tac-toe. It is composed of many dual- input logical and gates which are fed by an input-memory p-4:12 Q g..l1'f-.2 ry by elf: iiiigsiii 4 s ' s 3 ' 4 . 15 3515114 ' if-ilslffii iii? l L'fii.3 ii i Fil? 1 ' ' ' sliifg A Q-xiii - . ' T f--Q ' 3111 .Mgt 1' -- Z Ll? L.-:Jia THE LUGIC DF TIS-THErT'Z 2 '-UMC '?f!'if5'lB!XE?'!'F3199f' if' 3 of five stepping switches. These are sequenced and triggered by a sixth stepper and a telephone dial. There are 36 different inputs, nine for each of the different moves, first through fourth. The outputs of the ands and wired in parallel to nine multi-input or gates: one for each of the nine outputs. These feed two-stage transistorized output amplifiers which light bulbs on the display unit. The logic was determined by playing each of the ap- propriate games out and compiling them into a table of numerical game sequences. l