Anyone have built succesfully (no bleedthrough signal) a CMOS Nyquist Aliaser?

[brett]

Hi
I've had a good look at the schematic and it's different to my first impressions.  My comments about Vref were way off.   
However, resistor matching is still a good idea. 
I've got a couple of ideas about improving this circuit.  It could be built on a single CD4016, for example.  The first switch, that "squares up" the signal isn't necessary, and potentially adds some problems.  Also, my preference is to avoid coupling capacitors, such as the one used here.  If I get time in the next few days, I'll draw a schematic and PCB.
cheers

[gigimarga]

Hi
I've had a good look at the schematic and it's different to my first impressions.  My comments about Vref were way off.   
However, resistor matching is still a good idea. 
I've got a couple of ideas about improving this circuit.  It could be built on a single CD4016, for example.  The first switch, that "squares up" the signal isn't necessary, and potentially adds some problems.  Also, my preference is to avoid coupling capacitors, such as the one used here.  If I get time in the next few days, I'll draw a schematic and PCB.
cheers

Thx a lot!!!
I will wait with my heart hard beating

[gigimarga]

 

[bioroids]

Hi
I've had a good look at the schematic and it's different to my first impressions.  My comments about Vref were way off.   
However, resistor matching is still a good idea. 
I've got a couple of ideas about improving this circuit.  It could be built on a single CD4016, for example.  The first switch, that "squares up" the signal isn't necessary, and potentially adds some problems.  Also, my preference is to avoid coupling capacitors, such as the one used here.  If I get time in the next few days, I'll draw a schematic and PCB.
cheers

Hi Bret!

If you want to improve the circuit, that would be very nice, as it seems the design has some serious flaws in it. But I wouldn't restrict to use only CMOS chips, that was just the FX Contest requirement when I designed it.

About using a single CD4016, I tried that in the first place, but it wouldn't work. That was my first deception with the circuit. I think there is some bleeding between the switches when used as amplifiers, at least that appeared to be happening on the breadboard.

I'm not in the position at the moment to keep tinkering with it, but go ahead I'd like to know what happens to it!

Regards

Miguel

[gigimarga]

Thx bioroids!

[John Lyons]

The one I built had a small amount of bleedthrough.
It wasn't very noticeable while playing through it.
Mostly at higher frequencies.
It's been a couple years since I built that...I sold mine
as I built it for a guy in the first place...

john

[gigimarga]

The one I built had a small amount of bleedthrough.
It wasn't very noticeable while playing through it.
Mostly at higher frequencies.
It's been a couple years since I built that...I sold mine
as I built it for a guy in the first place...

john

I don't have any luck with that...you was the only one which have built it and it functioned OK...did you used the PCB from the PDF or you made a personal one?


Thx a lot John!

[brett]

Hi
what about using 2 matched JFETs or MOSFETs (1 = input buffer/booster, 2 = hold/output buffer) with the 4016 oscillator and switch (minus the coupling cap).
A versatile (and somewhat superior) osccillator and switch (relative to the 4016) is a CMOS 555 and a discrete MOSFET switch (e.g. BS170/2N7000).
The 555 can sink and source a lot of current/charge.
cheers

[gigimarga]

Hi
what about using 2 matched JFETs or MOSFETs (1 = input buffer/booster, 2 = hold/output buffer) with the 4016 oscillator and switch (minus the coupling cap).
A versatile (and somewhat superior) osccillator and switch (relative to the 4016) is a CMOS 555 and a discrete MOSFET switch (e.g. BS170/2N7000).
The 555 can sink and source a lot of current/charge.
cheers

Is as you said...I'm waiting the result because it's too complicated for me

[John Lyons]

I used the PCB I made (as posted in the pdf).
No ground fill.


john

[gigimarga]

I used the PCB I made (as posted in the pdf).
No ground fill.

john

My last chance was gone...thx a lot!

[aloupos]

I have the same problem -- spent hours tweaking, never managed to get the carrier signal out.  I'd be really interested to see if someone here can solve it. 

[Taylor]

I don't think there's much solving to be done with this particular circuit. If you want this sound without the bleed, the simplest way to go is probably one of the aliasers with gates, like Crazy Larry or Nelson's Wolf Bagger/5 Knob Aliaser. I believe they both add clean blend, as well, which is a useful features for this sort of effect.

[gigimarga]

I don't think there's much solving to be done with this particular circuit. If you want this sound without the bleed, the simplest way to go is probably one of the aliasers with gates, like Crazy Larry or Nelson's Wolf Bagger/5 Knob Aliaser. I believe they both add clean blend, as well, which is a useful features for this sort of effect.

I've built both  of them, but  with no luck:

• Crazy Larry never worked for me: in the first attempt i made a PCB very hurried and i'm sure that it was a mistake in it and the one that and in the second i'd tried the one that Cliff Schecht posted here http://www.diystompboxes.com/smfforum/index.php?topic=73578.20 (thx a lot man again!) and no luck too...my mistake again i think...it's very stretched and my tools aren't very good
• Nelson's Wolf Bagger worked, but i couldn't obtain exactly the sound that i'm looking for...the sound of CMOS Aliaser with the frequency pot maximazied...after i've tried to mod it using a Nelson's mod it died

Now I'm trying to tweak a Nyquist Aliaser, but i still have a lot to work on it...but it seems to have the same problem: at high frequencies the bleedthrough is too strong.

Thx all for your kindness!

[slacker]

Have you tried JC's Nyquist aliaser? That has virtually no bleedthrough if you adjust it just right.

http://www.lynx.bc.ca/~jc/nyquistAliaser.html

[gigimarga]

Have you tried JC's Nyquist aliaser? That has virtually no bleedthrough if you adjust it just right.

http://www.lynx.bc.ca/~jc/nyquistAliaser.html

Thx slacker, now i am just trying to tweak a Nyquist Aliaser...maybe my mind is damaged, but for an aliaser i like only the settings at high frequencies...and in this case the Nyquist has a bleedthrough too...and i can't obtain with it so high frequencies

[gigimarga]

 

[brett]

Hi again
one of the "dangerous" things in a sampler is to connect/disconnect two sections with different bias.  In this case the input and output sections of the 4016 might be "floating" at slightly different voltages.  Even a *tiny* difference appears as bleedthrough (ie the switching makes a square wave with the amplitude of the voltage difference).

You might find that using another 4016 happens to work.  On the other hand, you might need to try 100 4016s before you get two sections identical.
I'll keep thinking about solving this issue.  (Maybe use dual supplies on a pair of op-amps and and tie the output and input signals solidly to DC ground?)
cheers

[gigimarga]

Thx a lot Brett!

Some trimpots doesn't help?

[gigimarga]

I re-tested all six 4016 that i have, from several manufracturers, with no luck...