Germanium or Silicon?

[crawler486]

Can you distinguish a Germanium from a Silicon
by just looking at it?

[Ge_Whiz]

Sometimes. It depends on your expertise. A very old germanium metal-can transistor looks very different from a modern plastic one, but there was a changeover period when the packaging was much the same. Some folks also have an encyclopaedic knowledge of the part numbers.

Generally, to the lay person, I would say 'no, you can't'.

[crawler486]

I scavenged some diodes that is clear and has black stripe,
can it be a germanium?

[brrt]

Could be. I can't think of a silicon diode in a clear package.

Brrt.

[acromarty]

A better way to distinguish is to measure the forward volt drop. A silicon diode drops about 0.7V, whereas a germanium diode drops about 0.3V.

You can't tell from the package unless you can decode the stripes into a number, like with resistor colour codes. Silicon diodes such as 1N914 or 1N4148 have a clear glass package with stripes.

Cheers,