SMD CMOS switch project

[odronn]

Inside the 4053 (or any other CMOS analog switch) there are bidirectional switches made by paralleling P and N type MOSFETS. So, technically it isn't true bypass, since there is a R_ON of the MOSFETS in the signal path.
For a more detailed read about the CMOS analog switches in general check this out: http://www.analog.com/static/imported-files/tutorials/MT-088.pdf

The intent of the transistor switching section is to avoid the conventional power switching via stereo jack, to improve the ground currents paths.
I could have not said it better than R.G.:

Why go to this trouble? It has to do with grounding issues and where the currents go. If you did the more common trick of just attaching the battery (-) lead to the ring terminal, 100% of the effect power flows into the effect on the same wire that carries the signal ground. So any current used in the effect causes a slight voltage wiggle on that wire, which the pedal amplifies. In many u can hear the result, sometimes from LEDs causing clicks or from oscillation and noise in high gain distortions.

(from http://www.geofex.com/FX_images/PNP_power_switching.pdf )

In this project, central ground point is at the lug of the DC connector.

[add4]

Thanks for the explanations.  So it's only useful if there is a power jack and batteries used?

[ggedamed]

Yep. Just like all your stompboxes.

[Crontox102098]

Looks great, which software used to design the PCB?

[odronn]

Altium Designer

[add4]

Does this projet uses the buffered or unbuffered 4049? if that matters at all here? (yes i'm trying it )
I plan on using a small microswitch and an actuator. is that a reliable solution?

[odronn]

Does this projet uses the buffered or unbuffered 4049? if that matters at all here? (yes i'm trying it )

You can use either type

I plan on using a small microswitch and an actuator. is that a reliable solution?

Yes it is, if you protect the microswitch from mechanical pressure of the actuator. You must somehow limit the actuator travel, so that the stomping pressure doesn't crush the microswitch.
If you do so, you have the most reliable switching mechanism of all.
However, it may be easier to use those metal momentary footswitches from ebay, that's what I intend to use.
Another nice idea: momentary arcade buttons

[duck_arse]

if you can get a microswitch with a "lever" fitted, you can use it to avoid the stomping forces being applied to your switch body. you can also get them with a roller on the end of the lever, which can be used with different types/shapes of actuators.

[Ice-9]

Don't waste the 3rd DPDT of the 4053 you can use it to add a stereo out with another jack. Mono in/ stereo out can be a very useful addition at no cost to PCB size in this case.