Some useful data on junction forming

I have read a couple of articles on junction forming that tend to contradict each other. The Bell System Journey helped clear it up a little. This article really explains in a clear way. Filing it here so I don't lose it.

Forming the junction

Thyristor as an amp

Using a voltage reg as an amp

A couple post back I gave some AF amps using TL431 regulator. This one should work with a 78L05. I'm posting it here before I lose it. To many projects not enough time and they seem to fall between the cracks if I don't make a note to come back to.

EDIT:
I put a notebook on my desk. The note says.
See blog post,using a voltage reg as an amp.

Reference for transistor making

These files are from Bell Lab Journal, Hobby magazines and the Defense document Center.
They give a couple of methods to make a transistor and test it for transistor action. There is an explanation for how the Point contact Transistor functions. (the PN hook)
You will also find data on the tunnel diode.
 
Physical Principles



Tunnel Diode


Surface Treatment of Germanium wafer

Homemade transistors

Make your own transistor

TL431 Phono Amp

This one is a cut and paste from the datasheet. The other two are modified versions.

Make you own transistor (from a diode) part 1

I have tried some different mounting methods. Each has it advantage and disadvantage. 3 of the 4 transistors show transistor action. I think I shot myself in the foot with the one. I tried putting a drop of Gallium on the wafer and soldering to it. The resulting junction did function as a diode but it looked like a tunnel diode.

 I think the one to the left was my best effort. I used some bronze shim stock for the point and it was much stiffer that the wire.

 I put the contacts against each other and used a piece of paper as a separator. It worked but I might find a thinner shim?

I used dual lugs. Mounted with screws so i can rotate them.

The first step is deciding how to lay them out so the points don't bump when brought into the wafer.

Bend a 90 degree stub to make a solder pad and then a hook. Trim the hook shorter so the point will be below it without hitting the mounting block.

So the rough layout. The three lugs in line and the distance set so the points will land on the wafer when rotated in place. The assembled unit is the left one on the first picture above. A closer look in the second picture above. This did give transistor action. I will have to locate the pictures of the assemble and post it tomorrow.

40/80 continues...........

The Chief Designer had made the prototype and it worked to well. He said it was a rats nest of jumpers but worked well. He would listen to it as he planned to make a good looking box and dress up the wiring. When the listening started that was the end of the bench work:).  I guess it filled the designer's dream, a set that worked so well it had to be used. Sadly he passed away Friday April 6, 2018. So the final build is what's presented here:

Rest in peace Andy. May the 40/80 live on. We started this design based on the oscillator Andy posted  last year. I reviewed it in earlier post. He said there was a different oscillator he would like to try. Sadly I never got the update so the set is complete except for the oscillator. I will be using the first design.

Andy's oscillator

This link goes to the oscillator that started the build.