On Sat, 31 Dec 2005 00:05:28 GMT, Paul VK3DIP wrote:
Hi all I recently purchased a bag of unmarked supposedly diodes and I am
trying to figure out what they are. The clues so far are normal diode
action on a multimeter (ie conducts one way but not the other) but the
forward voltage is high at about 1.4 - 1.5 volts. The packaging is a small
square black plastic box with flat axial leads one of which has a small
cross
piece on it. This packaging suggests small signal or at least low power.

If anyone wants to look at the mystery diode it is the top one
in this picture.
http://www.users.bigpond.com/pmcmahon/mysterydiode.jpg
The bottom one is a normal glass 1N914 just for scale.

There is nowhere for the light to come out (or in) so they are not LEDs
which is the only other diode like component I have come across with that
high a forward voltage. Could it be two silicon diodes in series?

Don't count it out as not being an LED. Some opaque-to-the-human-eye
packages are, in fact, quite clear in either the IR or UV range.
It could be an IR LED. (There's been many cases where light-sensitive,
'ordinary' diodes caused 'problems' in circuits on a well lit workbench.
The 'thing' would work one way in a buttoned-up case, and another way
under test.)

HTH
Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
Pueblo, Colorado | @ | Jonesy | OS/2 __
38.24N 104.55W | config.com | DM78rf | SK