Rob Judd wrote in message ...
Tom Bruhns wrote:
In a real diode, the change in slope is gradual with no sharp corners,
but if you could find a diode which looked like, say, 1000 ohms in the
reverse direction for all voltages and 1000.1 ohms in the forward
direction, it would still work as a detector, albeit a poor one.

Son, that's called a Selenium rectifier.

Goddam newbies.

Now if you'd mentioned copper oxide, I might have been mildly
impressed... ;-) Seems like there were some iron based ones, too.
And then there's the coherer...

Not all early detectors were insensitive, however. Have a look at the
Marconi detector which uses a moving magnetic band. Seems like we had
a thread here about it a few years ago, and there was a nice article
about it in EW+WW.

All the seleniums I ever used ('cept for the shorted ones) worked a
whole lot better than 10001:10000!

Cheers,
Tom