Boss electronic bypass switch PCB design: I made it! Here it is...

[Mark Hammer]

Assuming that an independent build confirms that the layout works as intended, this is a terrific addition, and much appreciated by at least one person here.  I've got a big sloped Hammond chassis I picked up surplus for $10, with holes for 8 momentary switches and what was apparently holes for a bunch of Boss pedals that had been housed in it.  The holes are a nice spacing for my foot, and given the structural solidness issues of larger sloped chassis, soft-touch switches are the way to go.

Jim is certainly right about 3PDT's being easier, but it is easy to think of many useful applications for a FET-based circuit.  In the case of commercial pedals that HAVE to assume they will be your only pedal, adding up all those buffers CAN make a difference in tone and noise.  But if they're YOUR pedals, and you KNOW you'll have 5 or 6 or 8 of them and you know what sequence they'll be in, you have much less obligation to have buffers before and after everything, and can simply use the switch.

As well, as is nicely explained in the DOD switch document by David Di Francesco at my site, these switches are easily modifiable to incorporate as many FETs as you want to produce more complex switching like order reversal and other things that a 3PDT can't do.  Finally, where 3PDTs that carry the audio signal have to be where the circuit is, the FET-based switch can be remotely controlled by a simple momentary....which could, for instance, be situated at the sound guy's desk.

[Unbeliever]

Finally, where 3PDTs that carry the audio signal have to be where the circuit is, the FET-based switch can be remotely controlled by a simple momentary....which could, for instance, be situated at the sound guy's desk.

The ability to 'remote-mute' a sloppy and out-of-tune lead guitarist was actually one advantage of this approach I thought of..... more complex (but more fun) would be to rig a logic-based  pedal system where if (say) the singer AND bass player or bass player AND drummer hit the 'mute guitarist' switch (at about the same time), then he gets muted for 1 minute (say). To make it fair, a similar system should be setup for the bass player, keys, singer etc. For the drummer, a real 'mute' would be impossible, however, activation of his/her 'mute system' would involve a robotic hand lowering a sheet of music in front of them; in my experience, this is sure to result in immediate confusion in said drummer and the cessation of all beating of skins.

[The Tone God]

There are different advantages to different switching systems be it stomp switches, relays, multiplexers (4053/4066), FETs, optos, etc. This system will allow users who's design criteria calls for a FET system to have the option. It is simply another tool in the DIYer's box.

Good job!

Andrew

[Morocotopo]

Unbeliever: What do you mean? Drummers are not musicians?
Mark: Did you ever build the DOD switch? I etched a PCB for it as provided by someone here called Difedetry or something like that, but I couldn´t make it work... Don´t know if the schematic has errors or the PCB was wrong... or I did something wrong. To me (very limited circuit experience), comparing this circuit and the DOD one, this one I can follow/understand the functionalitiy more or less, not so on the DOD one...

EVERYBODY NOTICED THE COMMENTS IN MY PREVIOUS POST ABOUT CAPS C 4, 5, 14, 6, 8, 13, RIGHT?

I´ll probably build it the next weekend to see if it works OK.

P.D: Mark, if I understood you right, you mean you could build this but without the in/out buffers? How would you do that (I mean, what parts of the circuit would you leave out?) I think I could eventually figure it out, probably it´s the in / out transistors and their associated R´s and C´s, right? But I´m not that good (actually, i don´t know how) at modding circuits...

[bioroids]

C6: 0.047uF
C8: 0.047uF
C13: 0.01uF

Tenes razon, C6 y C8 deben ser 0.047uf. C13 no estoy seguro.
En cuanto al diodo 1N4146, creo que lo podes reemplazar por un 1N4007.

english version:
You're right, C6 and C8 must be 0.047uf. I'm not sure about C13.
The 1N4146 diode can be replaced with a 1N4007 I think. Someone correct me if I'm wrong please.

Miguel

[JimRayden]

Finally, where 3PDTs that carry the audio signal have to be where the circuit is, the FET-based switch can be remotely controlled by a simple momentary....which could, for instance, be situated at the sound guy's desk.

The ability to 'remote-mute' a sloppy and out-of-tune lead guitarist was actually one advantage of this approach I thought of..... more complex (but more fun) would be to rig a logic-based  pedal system where if (say) the singer AND bass player or bass player AND drummer hit the 'mute guitarist' switch (at about the same time), then he gets muted for 1 minute (say). To make it fair, a similar system should be setup for the bass player, keys, singer etc. For the drummer, a real 'mute' would be impossible, however, activation of his/her 'mute system' would involve a robotic hand lowering a sheet of music in front of them; in my experience, this is sure to result in immediate confusion in said drummer and the cessation of all beating of skins.

Why evoke an unpleasant feeling of confusion? The cease of any noise caused by continuous whacking of skin-covered cylindrical objects can also be achieved by exposing a candy bar, which in turn will totally reorient the attention of the primate currently under discussion.



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Jimbo

[Unbeliever]

http://www.prosoundweb.com/recording/mm/week1/mm.php

[Gilles C]

I am one of the Boss fans about the FET switching...

Good job with the pcb. I did a couple pcbs for FET switching myself because I don't like pop-ups when I switch an effect.

And I like to switch some effects from a distance, which you can't do with true bypass.

I have some effects that have true bypass, some don't, and one uses a PIC controlled switching.

Keep on the good work.

Gilles

[Paul Perry (Frostwave)]

As a (tiny scale) manufacturer, I must say my life would have been easier if I'd used fet switching, so thanks! And, it's certainly true that mail order from South America is usually a frustrating, expensive, and uncertain process. I know that in Australia I have it easy, and I admire the DIYers that manage to stompbox in Brazil and Argentina.

[bioroids]

As a matter of fact, I never had a problem with shippings from Small Bear, the mail here is working pretty good. Only downside is added cost of shipping and taxes (50% of total cost !)

Luck!

Miguel

[nero1985]

actually electronic switching isnt that bad, you can use it to remotely bypass an fx, thats wat i usually do to boss pedals, i add a 1/4" jack to bypass the momentary switch when you plug a mono cable and then use a box to remotely bypass it, some people ive done it for use it for their boss pedals in the FX loop of their amps so its actually good to have

[Gilles C]

Just a last detail about true bypass vs fet switching.

First, I like to use a buffer right after the guitar when I use many effects to make sure the effects won't deteriorate the signal in the bypassed position.

And I always use a true bypass switchbox to be able to feed the guitar straight to the amp when I want to.

But that's just my taste anyway.

And Ralph, while looking at your pcb layout tonight, I found a little detail that I would have done another way. As you said that you didn't have a lot of experience, I though I could make you a suggestion about that detail. I hope that you won't mind, and you do what you want with it... It is just a suggestion.

It is just that normally, I find it better to have both conections for the LEDs close together. It permits to twist the 2 wires together right at the pcb.

As I said, it is just a thing that I like to do with pots and LEDs. I did a quick modification to your pcb just to show you how it would look.

Keep on the good work.

Gilles

Gilles

[Morocotopo]

Gilles, that´s great work. Your suggestions, as everyone´s,  are welcome. I don´t consider this PCB to be my "work/property", that´s why I posted it, so that anyone that wants to can add, correct, improve, criticize, etc. so that the end result is better than what any one single person can do (especially me!! ). So, it´s also your work/property now!!

By the way, who is Ralph? I´m morocotopo (hahahaha)!!!

Etching and prototyping today or tomorrow... stay tuned for news...

[Gilles C]

....
By the way, who is ? I´m  (hahahaha)!!! ....

Hummm.. in that "casemorocotopo not Ralph", you should change the name on the schematic...   

"Gilles not Gilles".

[Morocotopo]

Oh, I see where you got the name....
I´m not the one who made/drew the schematic, I just posted it for reference, I downloaded it from some page, or from this forum, I don´t remember.
Since I´m not the author, I don´t think I should change the names in the graphic file, don´t want to take credit for something I didn´t make, I just made the PCB for it.
But, it´s OK Gilles, you can call me Ralph if you want...

[ANDYEFFECT]

I've been thinking about playing with this circuit.
somebody else built? it works?

[Thecomedian]

Thanks for this, OP.

I tend to agree towards people who value the person providing such a circuit and its knowledge to the masses.

The electronic switch system is a "flip-flop". http://www.talkingelectronics.com/projects/5-Projects/Projects16.html and is designed to be stable in either state.

[maiko]

Kinda noob here in the forums but this project got me interested so i registered

I already made the circuit and the led turns on and off with the press of the switch.
my question is -- Can i test it outside a complete stombox circuit.  just to see if its 100% functioning and how to do that
I dont thing continuity testing will work as the signal goes thru a lot of components.

Any body also made this.    I could not get the 1n4146   i used a 4148.   

[slacker]

Going from the schematic in the first post if you connect your guitar to in and out to your amp it should pass signal in bypass mode, when the LED is off.  If you turn the LED on then you should get no sound because the path is broken where the effect would go. If you then connect effect in to effect out you should get sound.

[maiko]

thank you slacker for the reply

We i double triple checked everything i was kinda expecting to get a continuity reading on the in and out with the led off.   but i dont think ill get that with too many components in the path.   The only way i guess is to try your suggestion.   Will update ASAP