Diodes in Flatline Compressor

[MetalGuy]

Hi,

Is it critical to use Ge diodes in this compressor? Can I use Si or Schottky diodes instead and what modifications will be necessary if at all? Also what is the value of that photoresistor - I have some in the range of 1-3M but also couple of >200M ones?
Any help will be appreciated.

[Mark Hammer]

The diode type is really more of an extension of the amount of gain used in the circuit for the rectification.  Ge diodes don't need quite as much "drive" to be able to light up the LED.  Schottky types might work nicely, given their low forward voltage drop.  Changing to Si diodes *could* work, but you'd need to feed that cluster of 4 with a hotter signal to compensate.  My guess is the 47k feedback resistor would need to be increased, but I couldn't tell you what to do about the 330R resistor.

[MetalGuy]

Thanks for the quick answer! Obviously experiments will follow...

[Noplasticrobots]

Please update us on this MetalGuy, I'm interested myself (no Germs laying around...)

[MetalGuy]

Well, I tried 1N5819 Shottky diodes and very old detector Ge diodes. In the end I can say that it's more a matter of what kind of LED you're going to use. As somebody already pointed out you can use regular Si diodes but with a brighter LED.