I've played this game! Your picture is better though.

First guess, it is a small signal diode, similar to a 1N914.

You could connect it to a 20V power supply and reverse bias it to see if it is a zener.

The LED museum had a similar looking device that was an early LED.

Without markings it is almost impossible to be sure.

 

Ahh, if you connect it to a 20v power supply, the supply better be current limited or you'll have a glass passivated open connection with some burned rubble in the middle.

 

Opps, did I forget that little detail. It was in my head. Figure a 100KΩ resistor in series with it.

 

It looks like a point contact diode to me. I'm guessing it's germanium, maybe 1N34A.
If you look closely at the OP's picture, the s-curve in the catwhisker appears to be there, seen "on edge".

 

It's not a zener. I do believe it's a schottky because there is no reverse recovery time as measured from my scope. This diode looks like an old "cat whisker" from way back in the day. I was curious to see if anyone recognized it.

 

It's not a zener. I do believe it's a schottky because there is no reverse recovery time as measured from my scope. This diode looks like an old "cat whisker" from way back in the day. I was curious to see if anyone recognized it.

Did you see my post? Google "point contact diode" (images).

This site has great pictures of diode internals.

 

If you look closely at the OP's picture, the s-curve in the catwhisker appears to be there, seen "on edge".

The whisker has a bend, not so much an "s".

mmm, is that gold?

 

Looks a lot like this one, from the site I referenced in my previous post.

It is curious that you could see no reverse recovery time, because I don't think it looks like a Schottky diode.
How are you measuring Trr?
EDIT: I can't find a Trr spec on any germanium diode.

 

With a PN diode (FR3T):

With the mystery cat whisker diode:

 

I'm not sure how to interpret your time scale.

 

That's 500ns per div.

 

I'm trying to simulate this. What is the capacitance of your probe?
The diode in the top picture must be a pretty big one. What type is it?

EDIT: What are the rise/fall times of your generator?

 

I couldn't find the capacitance of these Rigol RP2200 1x/20x probes. The front panel of the scope says "all inputs are 1Mohm//15pF" though.

Rise/fall time is about 20ns.

Diode in top picture is a Toshiba FR3T. See attached datasheet.

 

With 20nS transition times, you won't see the Trr of a small-signal diode. For example, 1N4148 has a Trr of 4nS. I suspect point contact diodes are in that same range, because their junctions are tiny. From Wikipedia:

Point-contact diodes
These work the same as the junction semiconductor diodes described above, but their construction is simpler. A block of n-type semiconductor is built, and a conducting sharp-point contact made with some group-3 metal is placed in contact with the semiconductor. Some metal migrates into the semiconductor to make a small region of p-type semiconductor near the contact. The long-popular 1N34 germanium version is still used in radio receivers as a detector and occasionally in specialized analog electronics.

 

Interesting, thanks.

So my BK 4011 function generator has 20ns rise/fall times. A higher end model like the hp33120a has the same rise/fall times. I wonder what instrument can give me faster rise/fall times to test this sort of thing (trr of diodes)?

ps - found a picture of my diode here:
http://www.crystalradio.net/detectors/

 

Interesting, thanks.

So my BK 4011 function generator has 20ns rise/fall times. A higher end model like the hp33120a has the same rise/fall times. I wonder what instrument can give me faster rise/fall times to test this sort of thing (trr of diodes)?

ps - found a picture of my diode here:
http://www.crystalradio.net/detectors/

I could probably design a little circuit for you that would allow you to do this. You could still drive it from your function generator.
If you want me to do that:
What power supplies do you have available?
Do you have a stock of transistors and resistors? If not, who would you order from?

 

I have a ±(12 to 15)V @1A supply. I have a 0-20V @ 200mA supply. The latter is kinda flaky, it's an old RCA.

I have an extensive array of resistors: 1% and 5% kits. I have some typical transistors: 2n2222a (npn), 2n3906 (pnp), 2n7000 (n fet).

 

I'll try to use trannies that you have. If that doesn't work, you might need to buy a few.

 

I've got some other transistors; I just don't have a good idea of my inventory, as i'm away from my home lab. I'll write back later with more info.

Thanks for the help