Electronic – the purpose of the spring used in point-contact transistor


Below on the left side of the illustration there is a point-contact transistor which is the first transistor invented in 1947:

enter image description here

It seems the symbol of BJT actually comes from this point-contact transistor even though they operate very different way.

But what is the purpose of using a "spring" for establishing contacts?

In this source it is written:

The whole triangle was then held over a crystal of germanium on a
spring, so that the contacts lightly touched the surface.

Is that the reason for using the spring? To ensure a weak touch to the germanium surface? But if so, why is a weak/lightly touch is needed?


Another source from page 201 of the book called "Conquering the Electron":

enter image description here

Best Answer

You need enough force to maintain contact, but not so much that you crack the Ge crystal.

If you just directly connected the contact to the structure shown holding the spring, with no flexibility, it would be very easily to apply excess pressure and damage the crystal.