The General Approach to Computing - A Ramble

[Jim Battle]

Johnny Billquist wrote:
...
> Yes, you can build your own transistor. 

Yes, it is possible.

> It isn't difficult, and it isn't 
> expensive (well, compared to a transistor I guess it might be, but we're 
> still talking close to no money). 

Maybe it is possible to build a transistor that has poor gain, low 
bandwidth, and poor stability, probably like the first transistors made.

Jeri Ellsworth built some FETs and simple gates at home -- but she said 
it took two years to figure out how to make it work, and she needed some 
equipment (like vacuum chambers) that few people have at home.  It was 
far from simple.

http://trail.motionbased.com/trail/episode/view.do?episodePk.pkValue=8067618

Yes, that is a FET, not bipolar.  If you have some links for making 
simple bipolar transistors, please supply some.  It will make for some 
interesting reading.

I recall reading how IBM spent a lot of money and a lot of brainpower 
building their own transistors back in the early days.  If it really was 
all that simple, I doubt that IBM would have wrestled with it as much as 
they did.

> All it requires is two diodes. That's 
> all it is, really.

If you wire two diodes in series (PN->NP), it isn't the same as a 
transistor (PNP), at all.

> A transistor (and now I'm just talking about bipolar transistors, since 
> it's the easiest, and they are very common) is extremely simply to 
> understand and build.

I've heard of people disassembling a diode and making a point contact 
transistor, but that is already leveraging a lot of technology that put 
the $.10 diode in your hand to begin with.