Germanium diodes

[jimbob jones]

Im building a simple crystal reciever set. I am wondering if the diodes used in the detector stage have to be germanium diodes. And why is this?

 

[Nigel Goodwin]

Im building a simple crystal reciever set. I am wondering if the diodes used in the detector stage have to be germanium diodes. And why is this?

Yes they do, because a germanium diode has a far lower voltage drop than a silicon one, a silicon one requires around 0.7V to conduct, a germanium one only requires something like 0.2/0.3V (going from VERY distant memory!).

If you'e doing it 'properly' you should use a lump of galena and a 'cats whisker', and NOT a germanium diode 8)

Have a look at for some examples.

 

[Roff]

If you'e doing it 'properly' you should use a lump of galena and a 'cats whisker', and NOT a germanium diode 8)

Definitely! That's about 90% of the overall crystal set experience. My first crystal set was of the oatmeal box variety, back in about 1955. I bought a Philmore galena crystal embedded in a soft alloy (solder?) for about 25 cents from a local store (was Radio Shack around then?), then hunted all over town for #26 double cotton covered wire. Finally found some at a motor rewinding shop. I had no idea what the cotton was for, although I'm not sure I could have found enamelled wire any more easily even if i had known it was an option.

 

[Klaus]

Im building a simple crystal reciever set. I am wondering if the diodes used in the detector stage have to be germanium diodes. And why is this?

Yes they do, because a germanium diode has a far lower voltage drop than a silicon one, a silicon one requires around 0.7V to conduct, a germanium one only requires something like 0.2/0.3V (going from VERY distant memory!).

If you'e doing it 'properly' you should use a lump of galena and a 'cats whisker', and NOT a germanium diode 8)

Have a look at for some examples.

Just out of curiosity, has anybody tried this with a schottky diode? They have a low voltage drop that compares to a GE diode.
Klaus

 

[Roff]

**broken link removed** is a pretty thorough analysis of various detectors, including Schottky. One particular type of Schottky seemed to be the best detector he tested. I just skimmed the article, so I could be wrong.
A Google search of '"crystal set" schottky' yields some good hits.