Crystal Diodes
This is the ancient name for silicon, germanium, galena, and schottky diodes. It comes from the old days when a metal wire was mechanically touched to the galena crystal.
Hmmm that is why! I was seeing some very old schematics.
Thank you flatulent
The name is old but the definition is still valid.
A cristal detector is a sqare law, semiconductor, diode working with Vout in the mV range.
The Cristal detector is a basilar component for most advanced measuring instruments.
Look at this crystal Radio receiver schematic. Makes a little bit more sense now sergio mariotti. thanks
More information:
http://users.bigpond.net.au/emmerik/...s/crystal.html
http://www.sairem.com/Measure/Instru...ristaldetector
For a detector diode we want a fast diode (low parasitic capacitance compared to C in parallel LC tank) with a low threshold voltage. This is why Schottky's are used for this purpose. I suppose a while ago crystal diodes would have had agreeing performance, but clearly at higher price.
What is the price for crystal diodes? I got Schottky's one for cents.
In average, the price of a second-hand good crystal detector is S100.
http://www.ssejim.co.uk/rfdetectors.htm
For some applications they are very good, and cannot be replaced by anything, due to a very fast response (~200 pico seconds)
First available crystal diodes as far as I remember were germanium point diodes. They have very low capacitance and knee voltage, even lower than today's shotky diodes. I believe you can stil get AA116 or 1N34 diodes. Price is higher than for nowadays diodes.
ciao
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