CD4053 POPPING with Schematic and Voltages

[MarshallPlexi]

Hey Guys!

I'm trying to create a looper using the CD4053 and while it does work fine, I can't get away from the popping. Here is my schematic and voltages. Do ya'll see anything out of line? I have read everything I can find on this and still I can't seem to find the solution. I even tried changing the Vee pin to 9V thinking that might help but all it did was change the intensity of the popping/thumping.

Any ideas?



Voltages Ref Ground:

PIN 01 - 8.04
PIN 02 - 8.85
PIN 03 - 0
PIN 04 - 0
PIN 05 - 0
PIN 06 - 0
PIN 07 - 0
PIN 08 - 0
PIN 09 - 0
PIN 10 - 0
PIN 11 - 0
PIN 12 - 8.86
PIN 13 - 8.86
PIN 14 - 8.86
PIN 15 - 8.86
PIN 16 - 17.8 (edit: I had the breadboard pin 16 tied to 9V initially)

[Rob Strand]

Between R3 (10k) and pins 10 & 11 add a 1M in series and a 47nF cap to ground on pin 10 & 11 side of the added 1M.
This will slow down the switching transition.

Worth a try.  Even if that doesn't work it might help narrow down the cause.

Edit:
Why is your power rail at 9V?  You want the switch to be biased half of the supply of the 4053.   18V is pushing the
specs a bit (the TI parts seem to go to 20V).

That's going to cause pop for sure because the switch S1 connects to 18V.

[MarshallPlexi]

Between R3 (10k) and pins 10 & 11 add a 1M in series and a 47nF cap to ground on pin 10 & 11 side of the added 1M.
This will slow down the switching transition.

Worth a try.  Even if that doesn't work it might help narrow down the cause.

Why is your power rail at 9V?  You want the switch to be biased half of the supply of the 4053.   18V is pushing the specs a bit.

Like such?



The higher the supply voltage the lower the Ron. Also I don't want this MUX to clip hence I'm pushing it to the limits. Absolute Max Supply is 20V.

[Rob Strand]

Yes that but ...

Sorry I just edited my post while you posted that.

[MarshallPlexi]

Yes that but ...

Sorry I just edited my post while you posted that.

Just tried your suggestion and it takes the popping out and leaves more of a THUD....I take it as progress honestly.

[MarshallPlexi]

Yes that but ...

Sorry I just edited my post while you posted that.

I strapped a 0.22 cap across the 0.047uF and it's getting way better! Little too much capacitance as there is a small delay when I remove the HIGH condition. I think now it's a matter of adjusting the voltage divider we just made and adjusting capacitance along with it. I'll try a 1ML pot as my voltage divider so I can dial it in better.

Thanks so much for the good information Rob! I really appreciate it. You saved me from a depressing drive home!

[Rob Strand]

Thanks so much for the good information Rob! I really appreciate it. You saved me from a depressing drive home

Yes the larger the cap the less feed-through.

Your voltages imply pin 16 is at 9V.  You should connect it to 18V.
I suspect this is the root cause.  The extra large cap is now hiding that!

What happens is the 18V feeds into pin 10 & pin 11 then to the rest of the ckt through the C4053 input diodes.
It shouldn't do this. The added 1M limits the current and he cap limits the rate of change of voltage.
These are guaranteed to stop the feed through even though there is an undelying issue.

[MarshallPlexi]

Thanks so much for the good information Rob! I really appreciate it. You saved me from a depressing drive home

Yes the larger the cap the less the feed-through.

Your voltages imply pin 16 is at 9V.  You should connect it to 18V.
I suspect this is the root cause.  The extra large cap is now hiding that!

Pin 16 is at 18V.

I'm basing this off the RG KEEN article on the CD4053: http://www.geofex.com/article_folders/cd4053/cd4053.htm

Thus using pull up resistors to get all the pins of the CD4053 to 1/2V supply along with blocking caps to keep the DC where it belongs.

[Rob Strand]

Pin 16 is at 18V.

I'm basing this off the RG KEEN article on the CD4053: http://www.geofex.com/article_folders/cd4053/cd4053.htm

Thus using pull up resistors to get all the pins of the CD4053 to 1/2V supply along with blocking caps to keep the DC where it belongs.

That all looks good.

(Maybe you mis-typed your pin 16 voltage in the first post.)

[MarshallPlexi]

Pin 16 is at 18V.

I'm basing this off the RG KEEN article on the CD4053: http://www.geofex.com/article_folders/cd4053/cd4053.htm

Thus using pull up resistors to get all the pins of the CD4053 to 1/2V supply along with blocking caps to keep the DC where it belongs.

That all looks good.

(Maybe you mis-typed your pin 16 voltage in the first post.)

Oh man! Great catch! That's the difference between a schematic and a breadboard! I had it drawn right but not built right. It was indeed going to 9V even though the schem said 18V. I put it to 18V and it really didn't change anything that much. I still have work my way through the RC filter to slow the transition down.

Thanks for bringing that pin to my attention!

[anotherjim]

Maybe you should fit anti-pop pull-downs on all the jack socket tip contacts. Big at 10M.
Could you be testing with something plugged in that leaks DC?

RC debouncing the control switch is a good move, but I'd be happier with a flip-flop in there. R-S type (needs SPDT switch).

An RC to snuff out switch bounces needs to be just enough & no more or you might introduce a noticeable delay. As the switch contacts age, it gets to a point where that's no longer enough. RC delay means one CMOS switch might operate at a different time to the others (due to differening input thresholds), which could be bad in some applications.
The R-S flip-flop pretty much ignores the contact bouncing.

[MarshallPlexi]

Maybe you should fit anti-pop pull-downs on all the jack socket tip contacts. Big at 10M.
Could you be testing with something plugged in that leaks DC?

RC debouncing the control switch is a good move, but I'd be happier with a flip-flop in there. R-S type (needs SPDT switch).

An RC to snuff out switch bounces needs to be just enough & no more or you might introduce a noticeable delay. As the switch contacts age, it gets to a point where that's no longer enough. RC delay means one CMOS switch might operate at a different time to the others (due to differening input thresholds), which could be bad in some applications.
The R-S flip-flop pretty much ignores the contact bouncing.

I just installed 1M anti pop resistors on every jack. It didn't change anything. 

[MarshallPlexi]

This schematic shows the current state of affairs.

[Rob Strand]

I'd try lifting C2 to see if it has an effect.

Another tricky thing to try is to swap pins 1 and 2 and drive pin 10 with an inverted (and filtered) drive.
The idea here is positive charge is injected by one switch and negative by the other. Such tricks can reduce charge injection by a factor of 5 to 10.   The scheme anotherjim gave naturally gives you an inverting output.
The circuit isn't 100% symmetrical so it might not cancel as much in one state as another.

What load impedances do you have on the input/output?   When you have high impedance charge injection will cause large voltage glitches.   Just for a test you could try putting in 10ks instead of 1M.

I guess there's a few issues here:  1) What is causing the issue.  2) How to identify the cause.  3) Coming up with a solution.

I suspect there is something specific to you setup that's promoting the issue.

[Rob Strand]

I suspect there is something specific to you setup that's promoting the issue.

For example on your breadboard are any of the switch or 4053 control lines running next to audio lines.
Breadboards are notorious for introducing capacitive coupling between the rows.  Such capacitance may be more than the 4053!   Try connecting your breadboard base-plate to 0V as well.