Fuschia Fuzz JFET

Chuck D. Bones

Chuck D. Bones

Circuit Wizard
The Fuschia build docs call for an MPF4393 for Q1. That's what I used and it works well. But those are scarce and other JFETs will work. A schematic I found on the web indicates that the boxes built by BJFe use 2N5952. To work in this circuit, Q1 should have a Vp between 2 and 3V. Closer to 2V is better. Whatever JFET you use, best to test it before installing it. Also, when subbing JFETs be sure to verify the pinout because they are not all the same.
 
Chuck D. Bones said:
The Fuschia build docs call for an MPF4393 for Q1. That's what I used and it works well. But those are scarce and other JFETs will work. A schematic I found on the web indicates that the boxes built by BJFe use 2N5952. To work in this circuit, Q1 should have a Vp between 2 and 3V. Closer to 2V is better. Whatever JFET you use, best to test it before installing it. Also, when subbing JFETs be sure to verify the pinout because they are not all the same.
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I’m getting ready to build this one. Any idea for good substitute for the 2n1308 as I don’t have anything but a couple really low gain germanium’s. Also what target HFE and leakage should we be aiming for. Should this one be leaky like some of the Skreddys or low leakage? Thanks in advance.
 
This thread is about the JFET, but I'll answer your question here.
The Fuchsia is very forgiving re: Q3 specs. Just about any NPN Ge tranny will work. I'd look for HFE between 50 and 100, just an educated guess. When you say: "...really low gain germanium’s..." how low are we talking about?
 
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