Nyquist aliaser with envelope follower no sound problem.

[pinksoir]

Howdy.

So I built this on perfboard based on the following schematic:
http://www.moosapotamus.net/IDEAS/nyquist/NyquistENV2.gif

I copied the pcb layout from here:
https://sites.google.com/site/matthewkloiber/Layout1.png
https://sites.google.com/site/matthewkloiber/Layout2.png

And amended the layout as pins 2 and 3 of IC2 should be flipped around. R16  connected to the inverting input and C5, R15, and D2 connected to the non-inverting one, which was wrong.

So my perfboard layout is this:



There is no sound coming from the effect when it's engaged. Nothing at all. I have checked all connections, traces etc and it seems to be all correct. I substituted regular rimpots for precision trimpots.

Thanks a million.

[PRR]

Read the Debugging post at the top of this forum section.

Let's start with Q1 Q2 Q3 Q4, the direct audio path.

Base of Q2 is most interesting, ought to be in the 3V-7V range.

Short any two pins on Q3 (preferably Source-Drain, if you know which those are) and see if sound now passes.

[pinksoir]

Thanks a million for your reply, PRR.

I amended the image so's the components are labeled the same as the schematic. It was incorrect before...

I had a read of the debugging post and I'm going to buy a multimeter now today.

I'll try short the Source Drain pins on Q2 (incorrectly Q3 in the last image). They're the outside pins, right? They're the lower and middle pins in the layout I posted.

Thanks again.

[pinksoir]

Ok, so I had a poke around. When I shorted source-drain on Q2 sound passed through.

What does that mean?

[pinksoir]

So more news.

I found out that there was a bad solder joint which I corrected and now there is sound coming through!

However, it doesn't seem to be operating quite right. It sounds mostly like a fuzz. There's pretty much no nyquist aliasing going on, and definitely no envelope following.

But at least there is sound now. It is mostly a clean signal with a bit of distortion/fuzz on top. Playing with the trimpot 1 sort of adjusts the volume and fuzz level. Trimpot 2 doesn't seem to do much at all. Should I try changing them out for regular trimpots instead of precision ones? I tried changing them out. Trimpot 2 still doesn't seem like it's doing anything...

[pinksoir]

This was the first perfboard circuit I've made and I'm just wondering if I've done something really stupid. Did I solder everything in back to front?

Let me explain. I copied the perfboard layout I posted in the first post by copying these two files:





So on the physical board I made the components are as per the first image,but the traces are a mirror image of the second image. Should I have had the traces exactly the same as the second image and mirrored the components instead?

The way I see it now is that if I had printed my ow pcb using the second image, I would have had to place the components through the back of the board and soldered them in place so they would have been naturally mirrored

Or am i even more confused than I think I am?

[pinksoir]

??

[PRR]

http://www.diystompboxes.com/smfforum/index.php?topic=94010.msg810106#msg810106

[pinksoir]

PRR, I appreciate your help and I realise that I haven't posted what you asked for yet, but if you would look two posts above you I asked if I had soldered everything in backwards. I've searched around but I can't find any info anywhere (I know there must be some somewhere) but so far haven't come up with anything.

So, according to what I described above, have I soldered everything in backwards? Does that even make a difference?

Thanks.

[PRR]

> have I soldered everything in backwards? Does that even make a difference?

Makes no difference on most of the 2-pin parts.

Makes BIG difference in the 8-pin ICs.

I'm not inclined to compare-crosscheck layouts.

Voltage readings could give clues.

In particular look at the pinout for 5532 chip and see if the Vcc+ and Vcc- pins are +9V and ground respectively.