Today is nerd's Xmas. Oct. 31 = Dec. 25 Octal 31= Decimal 25

Transistors. Part 1. We began to consider this topic in our meeting on November 29, 2026. In part 1, we reminded ourselves Ohm's law and distribution of voltages in a series of two resistors. We considered the "load line" built in an assumption that one of the resistors in the series is the load to the other. Also, we introduced a "strange" resistor, the current through which is constant and does not depend on voltage, as long as the voltage is above a certain threshold level. We considered properties of this "strange" resistor and its behavior in a series with a normal resistor of constant resistance. A spoiler: In some ways, transistors are remotely similar to our "strange" resistor.

In today’s STT 2.2 meeting, we discussed two topics.   1. Lockheed SR-71 Blackbird This was a high-speed, high-altitude military reconnaissance jet airplane developed in the 1960s. This airplane was a real engineering feat. In designing it, so many contradicting requirements had to be satisfied.   Its cruising speed exceeding Mach 3, even at the altitudes of its flight that reached 26 km, caused heating of the hull to 600° C. Aluminum alloys lose strength at this temperature, so the hull had to be made of steel. Thermal expansion of the material was so strong that parts of the hull had to be made for this temperature to avoid mechanical stress, but at lower temperatures, they shrank, and the fuel tanks began to leak fuel, which had to be tolerated.   Turbojet engines cannot operate at such speeds and altitudes, so the engines were combined. They operated as afterburning turbojets at take-offs, subsonic and transonic speeds, and then, by switching the shape of the inlet and the inner airways of the engines, began to operate as a turbofan approximating a ramjet.   Normal fuel for jet airplanes was not suitable. Instead, special JP-7 fuel was used. Its volatility is low, and it is difficult to ignite. To start the engines, triethylboron was used. This substance ignites at contact with the air and produces sufficient temperature to ignite JP-7. Also, fuel was used as a coolant, for which it was pumped through pipes under the hottest parts of the hull before it was fed into the engines.   2. Transistors. Part 1. We began this topic, which will take several meetings to consider. We started not with transistors right away, but with simple things, like Ohm’s law. We introduced the load line of a series of two resistors, of which one is constant (the load) and the other is variable. Then we introduced an imaginary “strange” resistor, maintaining a constant current at any voltage exceeding a certain threshold value and considered its properties and behavior in a series of a constant resistor and our imaginary “strange” resistor.   Slides of this topic will be published later. ---------------- The meeting lasted 1 hour and 19 minutes. The next Sci-Tech Talks is scheduled for Thursday, 5 November.