February 1970 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
I have no idea why this quiz is titled what it is. LSI stands for "Large Scale Integration" and is generally applied to integrated circuits, not discrete components. The quiz's creator has come up with 17 questions, only the first of which has anything to do with LSI circuits. The other 16 are on topics like capacitor plate spacing, magnetorestrictive material, and coaxial cable. I realize that LSI attempts to minimize the number of external components necessary by absorbing them into the IC, but I'm just not sure what that has to do with whether a submarine can communication via SHF while submerged.
LSI Gives Semiconductors a "Trip"
By Vic Bell
A true-False Quiz That Covers the Electronics Waterfront
|1.||LSI is being used to "dope" many new types of semiconductor materials. ||TRUE____ FALSE ____|
|2.||If the third color band on a resistor is silver or gold, the resistor is either a 10% or a 5% unit and is less than 100 ohms. ||TRUE____ FALSE ____|
|3.||Spreading the outside plates on a variable air capacitor decreases its maximum capacitance. ||TRUE____ FALSE ____|
|4.||When two dissimilar metals are joined and heated, a voltage is developed across their junction. This is known as the Seebeck effect. ||TRUE____ FALSE ____|
|5.||"Skating force" is the side pressure exerted on a phonograph tone arm by the record groove spiral. It can be eliminated by using a dynamically balanced tone arm. ||TRUE____ FALSE ____|
|6.||A magnetostrictive material is one that changes its physical dimensions when magnetized. ||TRUE____ FALSE ____|
|7.||When a coil is wound around a magnetostrictive material core, a voltage is developed across the coil if a pressure is applied to the core. ||TRUE____ FALSE ____|
|8.||The Curie Point of a material is the temperature where it becomes radioactive. ||TRUE____ FALSE ____|
|9.||The resistances of both tungsten and carbon are inversely proportional to temperature.||TRUE____ FALSE ____|
|10.||The combination of two 10·ohm, 1/2-watt resistors in series will have the same power rating as the combination of two 40-ohm, 1/2-watt resistors in parallel. ||TRUE____ FALSE ____|
|11.||Infrared detection systems are of little use in desert areas because of the high sand temperature. ||TRUE____ FALSE ____|
|12.||The SCR is the solid-state equivalent of the d.c. latching relay. ||TRUE____ FALSE ____|
|13.||Submarines are capable of radio communications while submerged by using the SHF band. ||TRUE____ FALSE ____|
|14.||Rare earths now being used in color picture tubes are not really rare compared to many other elements. ||TRUE____ FALSE ____|
|15.||Coaxial cable cannot be made substantially smaller because frequency response dictates its size. ||TRUE____ FALSE ____|
|16.||An anisotropic magnet is one which has the same magnetic characteristics along any axis or direction. ||TRUE____ FALSE ____|
|17.||The first half of the horizontal sweep in a normal TV receiver (left side of the screen) is formed by the damper circuit. ||TRUE____ FALSE ____|
1. False - LSI stands for Large Scale Integration.
2. False - The third band on a resistor always designates a multiplier. When the third band is silver, the multiplier is 0.01; gold is 0.1. For instance, a red-red-gold-silver resistor would be 2.2 ohms with 10% tolerance.
3. True - Increasing the distance between the plates on any air-spaced capacitor decreases its capacitance.
4. True - The Seebeck and the thermoelectric effects are the same.
5. False - A dynamically balanced tone arm will not correct skating force. A slight opposing force, proportional to stylus pressure, is normally used to counter the skating force.
6. True - Magnetostrictive materials (nickel, stainless steel, iron) are used as transducers in ultrasonic equipment.
7. True - Just as a magnetic field causes a change in size, so can a change in size of the cone cause a magnetic field. The field, of course, generates a voltage in the coil.
8. False - The Curie Point is the temperature above which a ferromagnetic material becomes practically non-magnetic.
9. False - Tungsten's resistance is directly proportional to temperature but carbon is inversely proportional.
10. True - Each resistor in a series circuit absorbs half the total power. Either configuration will have the same power rating.
11. False - Most infrared missile systems are test-fired on desert ranges. These systems operate on a temperature differential, not ambient temperature.
12. True - In both cases, the power must be removed from the device so that it "unlatches" and a pulse is all that is required to energize them.
13. False - Radio communication with submerged submarines is carried on in the VLF band.
14. True - Most rare earths are not now considered rare.
15. False - A 50-ohm coaxial cable is now available measuring only 0.0104 inches in diameter. Losses are increased with the reduction in size, however.
15. False - An anisotropic magnet has an axis with preferred characteristics over other axes. An isotropic magnet has no preferred axis.
17. True - After the flyback, the damper tube charges the boost capacitor which forms the first half of the sweep.