There's a big difference between filing a patent and having a working prototype.

There was enough working prototypes (1938, Third Reich, Paul & Hilsh, later, 1939 USSR, Losev), but since there was golden era of cheap and well-known vacuum tubes, and first FETs does not show good gain, speed and reliability, they was mostly an objects in science labs. When technology throw a call to a smaller electronic components, transistors went from labs to production.

Meanwhile, vacuum tubes is still have advantages over transistors, and still have use in, mostly military, high endurance devices designed to stand EMP from nuclear explosion.

In any case, there was no any need for aliens to start mass-production of transistors. Theory was already developed, prototypes worked, and the question was only in a demand and mass-production process.

The difference from vacuum tubes to transistors is bigger than the difference between the wright brothers first flight and a stealth bomber and we closed that gap in a blink of an eye.

Vacuum tubes and transistors have nothing common at all. They are from completely different regions of science, and have absolutely different, parallel ways of creation that never crossed. There was no any "vacuum tube to transistor" sequential steps at all. Interesting, that vacuum tubes as diodes and semiconductors as diodes was discovered nearly at the same time (1873 and 1874) and completely independently. So, semiconductor components have same age as vacuum tubes.

And Wright plane and stealth bomber are both planes that use wings to create lift, and Wright plane is direct ancestor of steath bomber.

If you are looking for alien technology, it is better to take a look at medicines. Some medicines looks like appeared from nowhere, without any prior works, just somebody synthesize very complex compound, and it works form the first test. It is at least very suspicious.

Do you remember hearing about the "flight school" in Africa where ETs visited a children's playground and told them that technology is destroying our civilization?

Yes. But that ETs are wrong. Technology is just a tool. It can't destroy civilisation by itself. Like an axe can't kill somebody by itself. It is humans (or non-humans if you like) who use technology to destroy civilisation. You have to get rid of that people, not of technology.

There's a big difference between filing a patent and having a working prototype.

There was enough working prototypes (1938, Third Reich, Paul & Hilsh, later, 1939 USSR, Losev), but since there was golden era of cheap and well-known vacuum tubes, and first FETs does not show good gain, speed and reliability, they was mostly an objects in science labs. When technology throw a call to a smaller electronic components, transistors went from labs to production.

Meanwhile, vacuum tubes is still have advantages over transistors, and still have use in, mostly military, high endurance devices designed to stand EMP from nuclear explosion.

In any case, there was no any need for aliens to start mass-production of transistors. Theory was already developed, prototypes worked, and the question was only in a demand and mass-production process.

The difference from vacuum tubes to transistors is bigger than the difference between the wright brothers first flight and a stealth bomber and we closed that gap in a blink of an eye.

Vacuum tubes and transistors have nothing common at all. They are from completely different regions of science, and have absolutely different, parallel ways of creation that never crossed. There was no any "vacuum tube to transistor" sequential steps at all. Interesting, that vacuum tubes and semiconductor diodes was discovered nearly at the same time (1873 and 1874). So, semiconductor components have same age as vacuum tubes.

And Wright plane and stealth bomber are both planes that use wings to create lift, and Wright plane is direct ancestor of steath bomber.

If you are looking for alien technology, it is better to take a look at medicines. Some medicines looks like appeared from nowhere, without any prior works, just somebody synthesize very complex compound, and it works form the first test. It is at least very suspicious.

Do you remember hearing about the "flight school" in Africa where ETs visited a children's playground and told them that technology is destroying our civilization?

Yes. But that ETs are wrong. Technology is just a tool. It can't destroy civilisation by itself. Like an axe can't kill somebody by itself. It is humans (or non-humans if you like) who use technology to destroy civilisation. You have to get rid of that people, not of technology.

There's a big difference between filing a patent and having a working prototype.

There was enough working prototypes (1938, Third Reich, Paul & Hilsh, later, 1939 USSR, Losev), but since there was golden era of cheap and well-known vacuum tubes, and first FETs does not show good gain, speed and reliability, they was mostly an objects in science labs. When technology throw a call to a smaller electronic components, transistors went from labs to production.

Meanwhile, vacuum tubes is still have advantages over transistors, and still have use in, mostly military, high endurance devices designed to stand EMP from nuclear explosion.

In any case, there was no any need for aliens to start mass-production of transistors. Theory was already developed, prototypes worked, and the question was only in a demand and mass-production process.

The difference from vacuum tubes to transistors is bigger than the difference between the wright brothers first flight and a stealth bomber and we closed that gap in a blink of an eye.

Vacuum tubes and transistors have nothing common at all. They are from completely different regions of science, and have absolutely different, parallel ways of creation that never crossed. There was no any "vacuum tube to transistor" sequential steps at all.

And Wright plane and stealth bomber are both planes that use wings to create lift, and Wright plane is direct ancestor of steath bomber.

If you are looking for alien technology, it is better to take a look at medicines. Some medicines looks like appeared from nowhere, without any prior works, just somebody synthesize very complex compound, and it works form the first test. It is at least very suspicious.

Do you remember hearing about the "flight school" in Africa where ETs visited a children's playground and told them that technology is destroying our civilization?

Yes. But that ETs are wrong. Technology is just a tool. It can't destroy civilisation by itself. Like an axe can't kill somebody by itself. It is humans (or non-humans if you like) who use technology to destroy civilisation. You have to get rid of that people, not of technology.