nquist aliaser pinout confusion

[jeff g]

I'm building the Nyquist Aliaser from this vero layout

http://www.diystompboxes.com/smfforum/index.php?topic=54141.0

I'm having what I think are transistor biasing problems, so I think I may not have transistors oriented correctly

In reading the tranistor info in the FAQ and other sources, I'm even more confused.

The Aliaser uses two transitor types:

1.  2N5210, with a pinout of EBC (flat side facing you, pins down) reading left to right

    So, wouldn't that mean that Q2 on the layout would have flat side facing right, not left as shown on the layout? (but Q5 would face left?)

2.  2N5457, with a pinout of DSG (flat side facing you, pins down) reading left to right

    In looking at the FET diagram in the FAQ, does that mean that you'd cross the S and G pins so that S  is in middle? And what direction does it face? Is there a diagram somewhere, not just the schematic version.

Thanks

[slacker]

1.  2N5210, with a pinout of EBC (flat side facing you, pins down) reading left to right

    So, wouldn't that mean that Q2 on the layout would have flat side facing right, not left as shown on the layout? (but Q5 would face left?)

Yes that's right, Q2 is the wrong way round on the layout, I'll change it.

2.  2N5457, with a pinout of DSG (flat side facing you, pins down) reading left to right

The FETs are correct on the layout for the pinout you've given, so just put them in as they are shown. No need to twist the leads or anything. Q6 needs to face the other way though, so the flat side is to the right.

Sorry for any confusion and good luck with it.

[slacker]

I've uploaded the corrected version, you might need to press refresh to see it.

[jeff g]

thanks for the verification slacker

next question ....  why doesn't it work

Here's the debugging info

1.Name of the project: Nyquist Aliaser

2.Links to the source of the project:http://www.diystompboxes.com/smfforum/index.php?topic=54141.0

3/4/5.  Followed layout with one sub: 2N3904 subbed for 2N5210;  had to put two resistors in series for 2m7.  Checked pinout - see above.  Checked cap orientation and parts values etc.

6. What it does and does not do how it works:
bypass works;
when engaged, effect can be heard and amplifies but does not modulate;
trimmers have no effect (or very minimal, maybe I'm imagining it);
volume pot works - no big change however

Measurements

Q1 - D=2.3 v
       S=0.57
       G= 0

Q2 - E=1.69
       B=2.30
       C=8.98

Q3   D=1.69
       S=1.69
       G=1.09

Q4 - D=8.98
       S=2.69
       G=1.69

Q5 - E=3.31
       B=3.93
       C=8.07

Q6 - D=3.56
       S=3.31
       G=1.38


IC

1=2.21
2=5.42
3=3.21
4=0.92
5=2.21
6=8.07
7=2.21
8=8.07

[oldrocker]

This circuit is tricky in many ways to get right.  I ended up using a J201 in the first position and 5952's for the rest in mine.  Then fine adjusting the trim pot which was fully counter clockwise on mine.  Originally I tried other fets and couldn't get it to work.  I tried all j201's all MPF102's all 5952's.  I did get some decent response using all 5952's but adding the J201 for the first fet sounded best to me.  When using he other fets I thought it wasn't working but I was and I didn't know it.  After re-tracing and trying to debug it I realized nothing was wrong and experimented and got it working.  So make sure there are no errors in the build and try different combinations with the Jfets.