Fetzer question

[fred43]

Ok so i'm pretty new to this and am having my brain bent with this.  Just wired up my first fetzer valve and can't seem to get it to work.  I've got current through the whole circuit until the output.  Everything stops at the cap into the out. 

Any help would be great, as i've pulled most of my hair out.

[wampcat1]

Ok so i'm pretty new to this and am having my brain bent with this.  Just wired up my first fetzer valve and can't seem to get it to work.  I've got current through the whole circuit until the output.  Everything stops at the cap into the out. 

Any help would be great, as i've pulled most of my hair out.

Are you using a 100k pot at the 'drain' to 9v? That's what I would do, and then slowly turn the pot (while strumming the guitar) until you get the bias sounding good.

Here is a quick diagram I drew up that might help you:


Take care,
Brian

[MartyMart]

That's cool Brian, though your output vol pot is "backwards" !
Swop lugs 1 & 3 to have it work correctly   
3 - circuit  2 - jack  1 - ground ..

MM.

[d95err]

Ok so i'm pretty new to this and am having my brain bent with this.  Just wired up my first fetzer valve and can't seem to get it to work.  I've got current through the whole circuit until the output.  Everything stops at the cap into the out. 

What exactly do you mean by "current through the whole circuit"? If you are measuring DC voltage, then it should read 0 after the output cap. The output cap is there to block DC, to ensure that only the signal passes through the output.

Read the "What to do when it doesn't work" sticky thread. If that doesn't help, measure voltages in the cirtuit and post them.

A short list of things to check:
* Make sure the signal isn't accidentally grounded somewhere
* Make sure electrolytic caps are wired with the correct polarity (+,-)
* Check the pinout on the transistor

Good luck!

[fred43]

thanks for the replies.  I've got sound now, it was grounding out and i had stared at the too long to go any farther.  Now the only problem i have is the volume i have is very little, almost a whisper.  I've adjusted the trim pot and i still have to turn it all the way up to get any sort of sound.  Anyone have any ideas on what i might be over looking?

[wampcat1]

That's cool Brian, though your output vol pot is "backwards" !
Swop lugs 1 & 3 to have it work correctly   
3 - circuit  2 - jack  1 - ground ..

MM.

Thanks 
That's what I get for working so late into the night!

[vitruviano61]

I'm having trouble with my Fetzer valve circuit as well.

I've rebuilt it several times, and am sure that I'm faithfully copying the schematic, as well at the layout illustration appearing earlier in this thread.

When I bias the 100k trimmer, I can't approach the 4.5v specified for the drain without causing the circuit to sqeal and oscillate wildly.

About 1.8v is as high as I can go. My voltage at the source is 1.09-1.11v, which is within range for the 2N5457 I'm using, according to the Fetzer chart at ROG.

At this level, I can get sort of a fizzy distortion, which was not at all how I imagine the circuit should sound.

I've verified all resistors with a DMM, and they're okay.

The circuit works, but barely, and is disappointing, in stark contrast to the enthusiastiasm this circuit has generated among many others.

Grateful for any suggestions or insights to the biasing issue.

best,
--v

[Satch12879]

Sounds like we're perhaps learning that all JFETs are not created equal.