Lesson:He Fixes Radios by Thinking! - Revision history

Gustavo at 12:00, 11 November 2021

2021-11-11T12:00:48Z

Gustavo at 11:50, 4 November 2021

2021-11-04T11:50:29Z

Solernevital at 12:51, 22 August 2015

2015-08-22T12:51:01Z

Alvaro: /* Part G */

2015-08-03T22:19:15Z

Part G

Alvaro: /* Part G */

2015-08-03T22:12:18Z

Part G

Alvaro: /* Part G */

2015-08-03T22:02:46Z

Part G

Alvaro: /* Part D */

2015-07-31T22:11:14Z

Part D

Gustavo at 03:50, 20 August 2014

2014-08-20T03:50:16Z

Millateixeira at 18:07, 10 March 2014

2014-03-10T18:07:58Z

Millateixeira: /* Part A */

2014-03-10T18:06:06Z

Part A

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 Sometimes it took quite a while. I remember one particular time when it took the whole afternoon to find a burned-out resistor that was not apparent. That particular time it happened to be a friend of my mother, so I had time-there was nobody on my back saying, "What are you doing?"
-Instead, they were saying, "Would you like a little milk, or some cake?" I finally fixed it because I had, and still have, persistence. Once I get on a puzzle, I can't get off. If my mother's friend had said, "Never mind, it's too much work," I'd have blown my top, because I want to beat this damn thing, as long as I've gone this far. I can't just leave it after I've found out so much about it. I have to keep going to find out ult imately what is the matter with it in the end.
+Instead, they were saying, "Would you like a little milk, or some cake?" I finally fixed it because I had, and still have, persistence. Once I get on a puzzle, I can't get off. If my mother's friend had said, "Never mind, it's too much work," I'd have blown my top, because I want to beat this damn thing, as long as I've gone this far. I can't just leave it after I've found out so much about it. I have to keep going to find out ultimately what is the matter with it in the end.
-That's a puzzle drive. It's what accounts for my wanting to decipher Mayan hieroglyphics, for trying to open safes. I remember in high school, during first period a guy would come to me with a puzzle in geomet ry, or something which had been assigned in his advanced math class. I wouldn't stop until I figured the damn thing out--it would take me fifteen or twenty minutes. But during the day, other guys would come to me with the same problem, and I'd do it for them in a flash. So for one guy, to do it took me twenty minutes, while there were five guys who thought I was a supergenius.
+That's a puzzle drive. It's what accounts for my wanting to decipher Mayan hieroglyphics, for trying to open safes. I remember in high school, during first period a guy would come to me with a puzzle in geometry, or something which had been assigned in his advanced math class. I wouldn't stop until I figured the damn thing out--it would take me fifteen or twenty minutes. But during the day, other guys would come to me with the same problem, and I'd do it for them in a flash. So for one guy, to do it took me twenty minutes, while there were five guys who thought I was a supergenius.
-So I got a fancy reputation. During high school every puzzle that was known to man must have come to me. Every damn, crazy conundrum that
+So I got a fancy reputation. During high school every puzzle that was known to man must have come to me. Every damn, crazy conundrum that people had invented, I knew. So when I got to MIT there was a dance, and one of the seniors had his girlfriend there, and she knew a lot of puzzles, and he was telling her that I was pretty good at them. So during the dance she came over to me and said, "They say you're a smart guy, so here's one for you: A man has eight cords of wood to chop . . ."
 And I said, "He starts by chopping every other one in three parts," because I had heard that one.

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-On this same tube radio up in my lab I was able to hear a station up in Schenectady called WGN. Now, all of us kids-- my two cousins, my sister, and the neigh borhood kids--listened on the radio downstairs to a program called the Eno Crime Club--Eno effervescent salts--it was the thing! Well, I discovered that I could hear this program up in my lab on WGN one hour before it was broadcast in New York! So I'd discover what was going to happen, and then, when we were all sitting around the radio downstairs listening to the Eno Crime Club, I'd say, "You know, we haven't heard from so-and-so in a long time. I betcha he comes and saves the situation."
+On this same tube radio up in my lab I was able to hear a station up in Schenectady called WGN. Now, all of us kids-- my two cousins, my sister, and the neighborhood kids--listened on the radio downstairs to a program called the Eno Crime Club--Eno effervescent salts--it was the thing! Well, I discovered that I could hear this program up in my lab on WGN one hour before it was broadcast in New York! So I'd discover what was going to happen, and then, when we were all sitting around the radio downstairs listening to the Eno Crime Club, I'd say, "You know, we haven't heard from so-and-so in a long time. I betcha he comes and saves the situation."
 Two seconds later, bup-bup, he comes! So they all got excited about this, and I predicted a couple of other things. Then they realized that there must be some trick to it--that I must know, somehow. So I owned up to what it was, that I could hear it upstairs the hour before.
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 One day, when I had my earphones on, I connected them to the loudspeaker, and I discovered something: I put my finger in the speaker and I could hear it in the earphones; I scratched the speaker and I'd hear it in the earphones. So I discovered that the speaker could act like a microphone, and you didn't even need any batteries. At school we were talking about Alexander Graham Bell, so I gave a demonstration of the speaker and the earphones. I didn't know it at the time, but I think it was the type of telephone he originally used.
-So now I had a microphone, and I could broadcast from upstairs to downstairs, and from downstairs to upst airs, using the amplifiers of my rummage-sale radios. At that time my sister Joan, who was nine years younger than I was, must have been about two or three, and there was a guy on the radio called Uncle Don that she liked to listen to. He'd sing little songs about "good children," and so on, and he'd read cards sent in by parents telling that "Mary So -and-so is having a birthday this Saturday at 25 Flatbush Avenue."
+So now I had a microphone, and I could broadcast from upstairs to downstairs, and from downstairs to upstairs, using the amplifiers of my rummage-sale radios. At that time my sister Joan, who was nine years younger than I was, must have been about two or three, and there was a guy on the radio called Uncle Don that she liked to listen to. He'd sing little songs about "good children," and so on, and he'd read cards sent in by parents telling that "Mary So-and-so is having a birthday this Saturday at 25 Flatbush Avenue."
-One day my cousin Francis and I sat Joan down and said that there was a special program she should listen to. Then we ran upstairs and we
+One day my cousin Francis and I sat Joan down and said that there was a special program she should listen to. Then we ran upstairs and we started to broadcast: "This is Uncle Don. We know a very nice little girl named Joan who lives on New Broadway; she's got a birthday coming--not today, but such-and-such. She's a cute girl." We sang a little song, and then we made music: "Deedle leet deet, doodle doodle loot doot; deedle deedle leet, doodle loot doot doo We went through the whole deal, and then we came downstairs: "How was it? Did you like the program?"
 "It was good," she said, "but why did you make the music with your mouth?"

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 One thing was for sure: It was practically impossible to do the problem in any conventional, straightforward way, like putting "A is the number of red books, B is the number of blue books," grind, grind, grind, until you get "six books." That would take you fifty seconds, because the people who set up the timings on these problems had made them all a trifle short. So you had to think, "Is there a way to see it?" Sometimes you could see it in a flash, and sometimes you'd have to invent another way to do it and then do the algebra as fast as you could. It was wonderful practice, and I got better and better, and I eventually got to be the head of the team. So I learned to do algebra very quickly, and it came in handy in college. When we had a problem in calculus, I was very quick to see where it was going and to do the algebra--fast.
-Another thing I did in high school was to invent problems and theorems. I mean, if I were doing any mathematical thing at all, I would find some practical example for which it would be useful. I invented a set of right-triangle problems. But instead of givin g the lengths of two of the sides to find the third, I gave the difference of the two sides. A typical example was: There's a flagpole, and there's a rope that comes down from the top. When you hold the rope straight down, it's three feet longer than the pole, and when you pull the rope out tight, it's five feet from the base of the pole. How high is the pole?
+Another thing I did in high school was to invent problems and theorems. I mean, if I were doing any mathematical thing at all, I would find some practical example for which it would be useful. I invented a set of right-triangle problems. But instead of giving the lengths of two of the sides to find the third, I gave the difference of the two sides. A typical example was: There's a flagpole, and there's a rope that comes down from the top. When you hold the rope straight down, it's three feet longer than the pole, and when you pull the rope out tight, it's five feet from the base of the pole. How high is the pole?
 I developed some equations for solving problems like that, and as a result I noticed some connection--perhaps it was sin2 + cos2 = 1--that reminded me of trigonometry. Now, a few years earlier, perhaps when I was eleven or twelve, I had read a book on trigonometry that I had checked out from the library, but the book was by now long gone. I remembered only that trigonometry had something to do with relations between sines and cosines. So I began to work out all the relations by drawing triangles, and each one I proved by myself. I also calculated the sine, cosine, and tangent of every five degrees, starting with the sine of five degrees as given, by addition and half-angle formulas that I had worked out.

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 While I was doing all this trigonometry, I didn't like the symbols for sine, cosine, tangent, and so on. To me, "sin f" looked like s times i times n times f! So I invented another symbol, like a square root sign, that was a sigma with a long arm sticking out of it, and I put the f underneath. For the tangent it was a tau with the top of the tau extended, and for the cosine I made a kind of gamma, but it looked a little bit like the square root sign.
-Now the inverse sine was the same sigma, but left -to-right reflected so that it started with the horizontal line with the value underneath, and then the sigma. That was the inverse sine, NOT sink f--that was crazy! They had that in books! To me, sin_i meant i/sine, the reciprocal. So my symbols were better.
+Now the inverse sine was the same sigma, but left -to-right reflected so that it started with the horizontal line with the value underneath, and then the sigma. That was the inverse sine, NOT sine to the negative one f--that was crazy! They had that in books! To me, sin_i meant i/sine, the reciprocal. So my symbols were better.
 I didn't like f(x)--that looked to me like f times x. I also didn't like dy/dx--you have a tendency to cancel the d's--so I made a different sign, something like an & sign. For logarithms it was a big L extended to the right, with the thing you take the log of inside, and so on.

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 I developed some equations for solving problems like that, and as a result I noticed some connection--perhaps it was sin2 + cos2 = 1--that reminded me of trigonometry. Now, a few years earlier, perhaps when I was eleven or twelve, I had read a book on trigonometry that I had checked out from the library, but the book was by now long gone. I remembered only that trigonometry had something to do with relations between sines and cosines. So I began to work out all the relations by drawing triangles, and each one I proved by myself. I also calculated the sine, cosine, and tangent of every five degrees, starting with the sine of five degrees as given, by addition and half-angle formulas that I had worked out.
-A few years later, when we studied trigonometry in school, I still had my notes and I saw that my demonstrations were often different from those in the book. Sometimes, for a thing where I didn't notice a simple way to do it, I went all over the place till I got it. Other times, my way was most clever--the standard demonstration in the book was much more complicated! So sometimes I had 'em heat, and sometimes it was the other way around.
+A few years later, when we studied trigonometry in school, I still had my notes and I saw that my demonstrations were often different from those in the book. Sometimes, for a thing where I didn't notice a simple way to do it, I went all over the place till I got it. Other times, my way was most clever--the standard demonstration in the book was much more complicated! So sometimes I had 'em beat, and sometimes it was the other way around.
 While I was doing all this trigonometry, I didn't like the symbols for sine, cosine, tangent, and so on. To me, "sin f" looked like s times i times n times f! So I invented another symbol, like a square root sign, that was a sigma with a long arm sticking out of it, and I put the f underneath. For the tangent it was a tau with the top of the tau extended, and for the cosine I made a kind of gamma, but it looked a little bit like the square root sign.

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 I went up to the radio and tried to fix it. I didn't know anything about it, but there was also a handyman at the hotel, and either he noticed, or I noticed, a loose knob on the rheostat --to turn up the volume--so that it wasn't turning the shaft. He went off and filed something, and fixed it up so it worked.
-The next radio I tried to fix didn't work at all. That was easy: it wasn't plugged in right. As the repair jobs got more and more complicated, I got better and better, and more elaborate. I bought myself a milliammeter in New York and converted it into a voltmeter that had different scales on it by using the right lengths (which I calculated) of very fine copper wire. It wasn't very accurate, hut it was good enough to tell whether things were in the right ballpark at different connections in those radio sets.
+The next radio I tried to fix didn't work at all. That was easy: it wasn't plugged in right. As the repair jobs got more and more complicated, I got better and better, and more elaborate. I bought myself a milliammeter in New York and converted it into a voltmeter that had different scales on it by using the right lengths (which I calculated) of very fine copper wire. It wasn't very accurate, but it was good enough to tell whether things were in the right ballpark at different connections in those radio sets.
 The main reason people hired me was the Depression. They didn't have any money to fix their radios, and they'd hear about this kid who would do it for less. So I'd climb on roofs to fix antennas, and all kinds of stuff. I got a series of lessons of ever-increasing difficulty. Ultimately I got some job like converting a DC set into an AC set, and it was very hard to keep the hum from going through the system, and I didn't build it quite right. I shouldn't have bitten that one off, but I didn't know.

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