Help...Nyquist Aliaser with Envelope mod doesn't work!

[gigimarga]

Hi,

I've just finished a Nyquist Aliaser with Envelope Follower mod using this schematic: http://www.moosapotamus.net/IDEAS/nyquist/NyquistENV2.gif and this PCB: http://www.diystompboxes.com/smfforum/index.php?topic=72366.0.

I used BC549C instead of 2N5210 and i don't wired the CV input (i see no use for it right now).
All the FETs are 2N5457.

The clean signal pass through the effect with no mod, maybe it's a little compressed (but i'm not sure).
I cut the wire betwwen the Sensitivity pot and C4 to disconnect the Envelope Follower and no change.

"oldrocker" made some suggestions to me, but i have no 2N5952 to try...only some J201 and 2N3819.

I've looked on the JC Maillet's site, but the informations founded didn't help me.

I've read some posts, but it's clear that it's a sensitive build.

So, can anybody to indicate me some target voltages?
For exemple, it's ok to assume that i must to obtain 0V on Q5's base using VR2?

Thx a lot all!!

[gigimarga]

I replaced first JFET with J201 and no change.
What could be the voltage on Q1's drain?

[gigimarga]

 

[moosapotamus]

Is that a verified layout... has anyone else ever used it to build a working unit?

Thats' the first thing I would do... trace the scheme and layout side-by-side and convince your self that they are exactly the same.

~ Charlie

[gigimarga]

Is that a verified layout... has anyone else ever used it to build a working unit?

Thats' the first thing I would do... trace the scheme and layout side-by-side and convince your self that they are exactly the same.

~ Charlie

Thx for your advice Charlie!
Anyway, can you post some voltages from your unit?

[moosapotamus]

Actually, I breadboarded the whole thing to work out the envelope mod, and never built up a permanent one. Something else is living on my breadboard now, so I can't get any voltages for you. Sorry

~ Charlie

[ballooneater]

I think I may have found the source of your problems.  In my layout (the one in the first post), pins 2 and 3 of IC2 should be flipped around.  I had R16 (on my layout) connected to the inverting input and C5, R15, and D2 connected to the non-inverting one. 

So sorry for the inconvenience!

[gigimarga]

I think I may have found the source of your problems.  In my layout (the one in the first post), pins 2 and 3 of IC2 should be flipped around.  I had R16 (on my layout) connected to the inverting input and C5, R15, and D2 connected to the non-inverting one. 

So sorry for the inconvenience!

Thx a lot again ballooneater!!!
I think it's a problem for the envelope section, but mine doesn't work with this section disconnected, as a simple nyquist aliaser

[gigimarga]

I rechecked the PCB and it seems to be OK.
Any clues about the voltages?

[oskar]

For exemple, it's ok to assume that i must to obtain 0V on Q5's base using VR2?

No. If someone wanted 0V on that pin they would probably just have grounded it.

I rechecked the PCB and it seems to be OK.
Any clues about the voltages?

Actually, I think you are the one who should provide voltages. You have an envelope, a VCO, a S/H and whatelse.
Test one part of the circuit at a time. VCO... clock? ( use audioprobe ). Envelope out? ( U2b ( If you first reconnect it ))

[gigimarga]

Thx oskar...i will try to test it on modules

[gigimarga]

 

[gigimarga]

 

[aloupos]

I've been wanting to build this ... I'll throw a pcb together and see if I see the same results. 

[gigimarga]

I want to test it by modules, so which is the VCO and which is the S/H?

[oskar]

I want to test it by modules, so which is the VCO and which is the S/H?

VCO    U1A and the parts surronding...
S/H     Q2, Q3, Q4

[gigimarga]

Thx oskar!

[gigimarga]

 

[gigimarga]