🚀 go-pugleaf

(I wrote:)
>>...we concluded that germanium diode specs
>>were all kind of loose, and it was possible to duplicate (or even better)
>>all specs *except* FCD using silicon, and that's what nearly everybody
>>was doing! The ITT devices came in at 0.3V, and everything was fine.

(And Henry Spencer wrote:)
>I was sort of curious about this, and ran some tests on the 1N34s I've
>got in my parts box at home.  They are from Rockwell, I think -- at least
>the tiny symbol on the side looks like the Rockwell logo!  I *think* these
>are germanium; the current-vs-voltage curve does start to break at 0.3V.
>What startled me a bit was how gradual the rise was after that; within
>the limits of my simple measuring setup, it looked like a near-linear rise
>at about 1mA/100mV, whereas the one for a 1N4148 is nearly vertical at
>circa 0.6V.  Is this normal for germanium, or have I got something funny
>like silicon pretending to be germanium?
>-- 
>That's not a joke, that's      |     Henry Spencer at U of Toronto Zoology
>NASA.  -Nick Szabo             | uunet!attcan!utzoo!henry henry@zoo.toronto.ed
u


Checking a mid-50's Sylvania reference, they say a 1N34 can have a forward
resistance of 200 ohms max. at 1 volt, so your result is not out of line.
Sounds to me like you've got the real thing. Gonna build a crystal set?

Something way in the back of my mind is saying there is/was some kind
of alliance or merger or something concerning Rockwell and ITT. I'm
really not sure; just a feeling....

As long as we're still on the subject, someone (sorry, lost the attribution)
said it would be easy to tell Si from Ge just by checking the data sheet;
I presume they haven't read too many older data sheets, which tended to be
a bit sparse by today's standards.

Here's *all* Sylvania (the manufacturer) had to say about the 1N34:

    Description:                          General Purpose Diode
    Ambient Temperature Range (deg C):    -50 to +75.

(All following ratings are specified at 25 C only)

    Continuous Reverse Working Volts:     60
    Recurrent Peak Anode Current (ma):    150
    Average Anode Current (ma):           50
    Surge Current (ma, 1 sec):            500
    Peak Reverse Voltage (Volts min):     75
    Forward current at +1V (ma, min):     5
    Reverse Current (microamps, min):     30 @ -10V, 500 @ -50V
    Forward Resistance at +1V (ohms max): 200
    Reverse Resistance (ohms min):        333K @ -10V, 100K @ -50V

Well, I dunno. About the only clue I get from that as to what kind of
diode it is, is *not a very good one*. That's why manufacturers could
substitute Silicon (floor sweepings, even) and still satisfy the "spec". 

Nostalgia time: Early 1N34's were point contact devices packaged in a
ceramic tube with screw-on metal end caps (looked like a short fuse).
There were construction articles on how to take two of these things
apart to get the tungsten cat whiskers, and put both of them *real
close together* on one of the germanium crystals to make your own transistor.

I never got it to work.

Isaac
isw@cup.portal.com