Coda Relay Bypass - Clicks while playing & possible improvements? ( Noob here )

[abakuzam]

Hello everyone, i have been playing around with Coda's relay bypass ( https://www.coda-effects.com/2017/02/relay-bypass-final-code.html ) to have better diy stompboxes, he did an amazing job , i want to appreciate that first  I read quite a bit about relay bypass with uC and muting, still i have some questions and i don't know coding but i read Coda's great tutorial, i have some understanding about that.


About my questions ;

1) I used this schematic & layout :  http://www.madbeanpedals.com/EP/schematics/Coda-BYP.gif , used Takamisawa NA5W-K relay. Rest of the components are the same.

Relay dataseheet: https://www.fujitsu.com/downloads/MICRO/fcai/relays/na.pdf

2) I think i should add a flyback diode to that circuit?

3) It works quite well, but i get little audiable pops & clicks when engaged or disengaged, especially when i play low strings , or guitar connected to the pedal. When i don't play, or roll the guitar volume all the way down, no clicks or pops. Also my led seems to turn on instantly unlike Coda's video ( https://www.youtube.com/watch?v=AifpuBymJU0 ). I sourced my parts from Arrow ( PIC, Relay and TLP222A ). I'm not sure led timing is too important for clicks.

5) I have read in somewhere ( can't remember where ) that it's actually caused from muting system. I think optofet is turning on and off so fast that i have clicks and pops while playing and sometimes without playing. And the guitar input is not muted while muting the output.

6) Is there a way to make double muting? Before muting the output, can we mute the input first with another optofet and after input is muted we can mute the output while dealing with all switch bouncing and other things that cause pops and clicks. Then output is unmuted , then input unmuted. Also input grounding configuration on the relay side ( as Madbean did ) . With this even we are playing the guitar while switching on & off, we wouldn't hear any clicks and pops? I'm not sure how to configure the timings.

7) Can we make this with current 12F675? and use jfet muting ( I think VFE did that ) for those purposes? I don't mind the costs that much, since my aim is just quality. Would jfet muting improve the switching?

If that' possible i would love to try it out and maybe put out some PCB layout etc. Much appreciated.

[yanng45]

Hello,

1) Keep in mind the way i do it is slightly different, it won't make any difference in the end i just have to mention it. I'm using a transistor driver for the relay like this :



PB3 being the GPIO pin on my microcontroller (an ATTINY85) and the relay is an OMRON G6K-2F : https://www.components.omron.com/product-detail?partNumber=G6K
I'm also using another photofet with very close characteristics to yours : https://toshiba.semicon-storage.com/info/docget.jsp?did=13665&prodName=TLP175A

2) Yes

3 -5) This is normal from my experience, the muting system is only here to cancel the switching noise from the relay. If you're playing while switching you get a little "pop" from the photorelay going on and off. You probably read that here : http://stompville.co.uk/?p=423 and, yes, i tried most of the solutions mentioned (cap, PWM...) and the best solution to achieve what the writer called a "soft mute" is to play with the photorelay's resistor value.

6) I think what you're trying to achieve is actually the way BOSS does it with their FET switching system. Look at the BD2 schematic for example, there's an article at GEOFEX describing that mechanism.

7) VFE did that, indeed, you can read about it here : http://www.madbeanpedals.com/projects/_folders/VFE/pdf/VFE_SwitchingBoard_v2.pdf, i tried it and some slight "pop" noise was still there. It could probably be tweaked but the photofet system was "good enough" for me and more convenient from a PCB layout point of view.

[abakuzam]

Hello yanng45, hope you are doing well

- I thought about putting transistor driver for relay, but i didn't have any misfires, i guess my pic can put enough current to drive the relay. I should add the diode for sure.

- I have read the article ( http://stompville.co.uk/?p=423 ) , understood the principles in general. I haven't tried the cap method yet, how was your results?

- I don't know any programming , perfect reason to start learning. Did you get better results with PWM? He mentioned about TLP222 can only handle audible frequency of <5kHz, i may look at optofets that can handle 40kHz as mentioned in the article. Would it be feasable?

- I have read the BOSS switching article. And yeah, similiar thing with relay, optofet and uC. Boss's version has too many compenents to fit in a small pcb.

And last one more question, i have seen quite a lot commercial pedals that uses some type of photofet switching with relay and uC, i never hear pops or clicks, how do they do that? Maybe i have bad setup in my home ( bad grounding in general ) for my amp, thus my guitar, i should try it on a different setup.

Thank you for giving me more information and sharing your experiences. Keep rocking!

[yanng45]

 - As i said the transistor driver won't make any difference, for me it was just a PCB layout commodity.

- No differences really, all it did was to delay the muting as mentioned in the article. I think in the end it's all about timing your photofet in relation to your relay. You can check my code here : https://github.com/effectspcbs/Arduino/tree/master/relay_switching/src but keep in mind that it is made for a different type of microcontroller (ATMEL ATTINY85 programmed with arduino in my case).

- I didn't go that way and i'm still learning about PWM for some other applications first to be honest.

- This is something i've learned pretty quickly since i started messing around with electronics : nothing comes free, it's all about compromises. Yeah their switching scheme takes a lot of PCB estate but, man, it is pretty rock solid.

It is true that once you put your idea onto a PCB with a proper grounding scheme the "pop" further goes away and is really indiscernible as long as your timings are okay. This is what you're hearing from commercial effects. Maybe that's all you're missing, you should give it a try !

[abakuzam]

- I should give your code a go, arduino seems very flexible, i saw some really cool projects, also i love learning, great oppurtunity for me.

- Yeah , it is rock solid, maybe i can do smd version for that system, with proper pcb layout ( still a begineer tho )

- It could be timing indeed, i will give it a try

Thank you again, much appreciated.

[matlevo12]

Hello everyone, i have been playing around with Coda's relay bypass ( https://www.coda-effects.com/2017/02/relay-bypass-final-code.html ) to have better diy stompboxes, he did an amazing job , i want to appreciate that first  I read quite a bit about relay bypass with uC and muting, still i have some questions and i don't know coding but i read Coda's great tutorial, i have some understanding about that.


About my questions ;

1) I used this schematic & layout :  http://www.madbeanpedals.com/EP/schematics/Coda-BYP.gif , used Takamisawa NA5W-K relay. Rest of the components are the same.

Relay dataseheet: https://www.fujitsu.com/downloads/MICRO/fcai/relays/na.pdf

2) I think i should add a flyback diode to that circuit?

3) It works quite well, but i get little audiable pops & clicks when engaged or disengaged, especially when i play low strings , or guitar connected to the pedal. When i don't play, or roll the guitar volume all the way down, no clicks or pops. Also my led seems to turn on instantly unlike Coda's video ( https://www.youtube.com/watch?v=AifpuBymJU0 ). I sourced my parts from Arrow ( PIC, Relay and TLP222A ). I'm not sure led timing is too important for clicks.

5) I have read in somewhere ( can't remember where ) that it's actually caused from muting system. I think optofet is turning on and off so fast that i have clicks and pops while playing and sometimes without playing. And the guitar input is not muted while muting the output.

6) Is there a way to make double muting? Before muting the output, can we mute the input first with another optofet and after input is muted we can mute the output while dealing with all switch bouncing and other things that cause pops and clicks. Then output is unmuted , then input unmuted. Also input grounding configuration on the relay side ( as Madbean did ) . With this even we are playing the guitar while switching on & off, we wouldn't hear any clicks and pops? I'm not sure how to configure the timings.

7) Can we make this with current 12F675? and use jfet muting ( I think VFE did that ) for those purposes? I don't mind the costs that much, since my aim is just quality. Would jfet muting improve the switching?

If that' possible i would love to try it out and maybe put out some PCB layout etc. Much appreciated.

Hi,

Old post, but are you still working on it ?
I've tried a few different things and mine works quite well. What code did you use ?

[absolvism]

[quote author=matlevo12 link=topic=123103.msg1176173#msg1176173 date=1585600796
Hi,

Old post, but are you still working on it ?
I've tried a few different things and mine works quite well. What code did you use ?
[/quote]

Hi Matlevo- Can I ask what you've found is working well for you?

[matlevo12]

Hi.
Sorry I just saw your message.
What do you mean ? Code-wise ? Circuit-wise ?