***help identifying a diode***

[mac]

I have a couple of diodes that look like Ge diodes, ie, glass case with a red band on one side, but voltage drop is about 550. Other Ge diodes I have, 1n60 & 1n34, have a drop of 270 - 300.
Can these diodes be Si disguissed as Ge?



mac

[calpolyengineer]

A picture or part number would go a long way to discovering the identity of your diode.

-Joe

[petemoore]

  Compare the foreward threshold voltage [set the DMM dial to '-->l--' diode checker], and compare that to data sheets or other known diode thresholds, those readings look like Si readings, but a little low?.

[mac]

i did that, it is closer to silicon readings. 1n4148 read 630, this diodes 550, other Ge 270.
they look exactly as the 1n34 aron shows in his store page, but these have a red band.
i do not need the exact type, all i want to know if they could be silicon.
thx


mac

[calpolyengineer]

They could be silicon. In those glass Ge ones, the small sliver of wire is not the Ge, the Ge is off to the side. The concept that works these diodes does work with Si too though, so they very well could be Si.

-Joe

[johngreene]

They could be silicon. In those glass Ge ones, the small sliver of wire is not the Ge, the Ge is off to the side. The concept that works these diodes does work with Si too though, so they very well could be Si.

-Joe

The comment on multimeters and measuring diode drops is interesting:

http://baec.tripod.com/articles/crystal.htm

Germaniums are always specified with a MAX Vf of 1.0V. So the data sheet isn't much help.

http://www.elexp.com/t_diode.htm

Probably because it's the drop at the MAX forward current.



--john

[mac]

The Ge diodes I have, 1n34, 0a91, aa117 and 1n60 fall in the range showed in the first link of the previous post.

I was thinking. This diodes were extracted from a distortion circuit I accidentally burnt long long time ago. They were a pair of back to back  to groung. One of the diodes is dead. The other is the one with the high voltage drop. Is there a chance that this diode was about to fry, and for this reason the voltage drop increased, ie, as if an excesive current can change the internal structure of the diode near the burning point making it a little more resistive or something??



mac