CMOS Switching

6/10/2014

Here's a good circuit if you want to avoid those clunky and expensive 3PDT switches and use a soft-touch momentary SPDT footswitch insted, or something else, like a push button switch.

One could argue that this one isn't really suitable for vero (tons of links...) or worth the effort, but I think it's nice for those extra special builds and it's also much cheaper than using relays. It does take a bit of space, but it can fit in a 1590B (depending on the size of the effect circuit).

9 Comments

Sergio

6/19/2014 04:33:49 am

Hallo, Im interested in your cmos switcher. Nice site by the way! So, what i was wandering is if that one introduces noise or delay between stomping and turning on /off. Another thing. Your numbering for the momentary switch is as follows?
1 closed
2 n open
3 n close

I ll try it soon with some delay and reverb fx.
Thank you!

Fredrik Lyxzén link

6/20/2014 03:56:22 am

Hallo!
Thanks for showing interest. :) The CMOS switch is very fast (faster then relay switching in general) and during my tests I have not noticed any added noise or pops. I'm not sure about the switch lug numbering but since it's a momentary switch the position of lug 1 and 3 should not matter. Try hooking it up with alligator clips to test before any final soldering.
cheers
/ Fredrik

Veit

1/27/2015 10:26:49 pm

Nice idea, but i think this isn`t true bybass, right?

Fredrik Lyxzén link

1/28/2015 06:58:59 am

Thanks! It's not my idea, I just did the layout. :) The signal isn't buffered and the effect is bypassed in off position and there is no "tone-sucking", so it's basically true bypass, but since there are electronic switching involved I wouldn't call it true true bypass. :P Read about it at: http://www.geofex.com/article_folders/cd4053/cd4053.htm

Aisha link

2/12/2015 02:38:42 am

Awesome!

hitesh

3/25/2016 07:43:50 pm

I made one circuit. for switching between two rotary encoders outputs. each encoder have 4 outputs. I used two cd4053. circuit works very well but in a result I got too much noice. I want to remove it. help me.

Fredrik Lyxzén link

3/29/2016 06:57:29 am

Hi Hitesh,
By noise, do you mean a switching pop? That's something I've had an issue with myself (but only together with some circuits - but those I could not solve) so I'm afraid I don't know what to do about it. This is good reading: http://www.mrblackpedals.com/blogs/straight-jive/6629778-what-really-causes-switch-pop
Maybe you can find something there that will help.
Best regards / Fredrik

Séb

5/6/2017 12:45:25 pm

Hi,
I've built an ABY pedal for my old Hiwatt DR103 (http://s1148.photobucket.com/user/paul_rowe2/media/buffered%20A-B-Y_zpsdfptgcke.jpeg.html), but I've got switching pop problems...
Do you have a "solution" for that with CMOS switching?
My set up :
Guitar->Tuner->ABY->SunnT preamp->Normal input
->Zvex SHO->Mi Audio Crunchbox->Bright input
(all effects DIY http://tagboardeffects.blogspot.fr/)
Thanks a lot and congratulations for your work on this site.
Séb

Fredrik Lyxzén link

5/6/2017 01:18:53 pm

Hi Séb
Sorry, I don't have any good/safe bet CMOS switching solution for your application. I've found that this CMOS bypass switching is hit or miss. I've only tried it with a handfull of circuits, but about half the time it didn't work out because of popping issues, so I rarely use this method. I think the safest pop-free method for switching is to use relays.

CMOS Switching

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