Re: Tunnel diode rectification

From: mike (spamme0_at_netscape.net)
Date: 03/09/05 

Date: Wed, 09 Mar 2005 11:30:46 -0800

Theo Markettos wrote:
> Fred Abse <excretatauris@cerebrumconfus.it> wrote:
>
>>On Mon, 07 Mar 2005 16:31:25 +0000, Theo Markettos wrote:
>>The valley floor has to be above zero, otherwise the device would contain
>>a voltage source.
>
>
> True, good point.
>
>
>>"Reverse breakdown" isn't really a property of tunnel diodes, they conduct
>>in the reverse direction more or less from zero.
>>
>>Tunnel diodes don't rectify, in the sense that I take you to mean the
>>term.
>
>
> Am I misreading something from the graph at:
> http://www.americanmicrosemi.com/tutorials/tunneldiode.htm
>
> which seems to suggest that they're basically like a Zener except the
> tunnelling current means they have a lower resistance at low applied
> voltages than at medium ones? I suppose the problem is lack of scale on the
> left/lower parts of the graph. It does seem to suggest that they're
> actually better at conducting in the reverse direction than the forward
> direction - is this true? I can't seem to find any datasheets on these
> diodes.
>
> My interest is for a crystal radio, where the forward voltage drop of a
> silicon, Schottky or germanium diode means you lose a lot of signal, but
> power isn't available. I was wondering whether a tunnel diode might be more
> efficient? Are there any other types of diode that might do the trick
> instead?
>
> Thanks
> Theo
>

How about a Germanium point-contact diode?
I've read reports that you can get the best performance with a real
Galena Xtal and real cat whisker...as long as you're willing to futz
with it.
You often get better results if the Subject line reflects your actual
objectives. Unlikely that a cat-whisker expert is gonna read a tunnel
diode post.
mike 

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