a polite schematic request

[no one ever]

Could somebody assist me in my search for the schematic of Boss' FET switching system? Any help would be greatly appreciated. 

[toneman]

Hi NOE,
All BOSS pedals use FET switching.
Pick one....
Then what?

stayswitched
tone

[JimRayden]

Hi NOE,
All BOSS pedals use FET switching.
Pick one....
Then what?

stayswitched
tone

I don't know if it's just me but this sure is one of the wierdest replies I've seen on this forum.

------------
Jimbo

[Harry]

I don't know if it's just me but this sure is one of the wierdest replies I've seen on this forum.

I think it makes sense:

Hi NOE,

N=No O=One E=Ever

All BOSS pedals use FET switching.
Pick one....

Well, I'll take his word for it.

Then what?

uhuh

stayswitched
tone

stayswitched I guess he's reffering to FET switching and is probably the "strangest" thing in his reply, and tone is his name and the closure.
You see it does make sense!

[toneman]

I don't know if it's just me but this sure is one of the wierdest replies I've seen on this forum.

Why, thanx 2 U , Jimbo.

staythinkin
or...
take your brain out, and let it wander......

tone

[southtown]

but after 4 posts i dont think this guy is any closer to getting the schematic

[gez]

but after 4 posts i dont think this guy is any closer to getting the schematic

The first reply was right.  Go to schematics and look under Boss/type in 'Boss schematics' into a search engine and they all (as far as I know) have the same FET switching scheme...

[spudulike]

Go here

http://www.freeinfosociety.com/electronics/schempage.php?cat=1

Loads of B*ss schematics.

[spudulike]

This may help better. Switching elements are in red. Can you work it out ?



Q5 and Q6 are a bistable, and the conductive state of the transistors changes when the footswitch takes their base caps low. This toggles the outputs (points C & D) from low to high and vice versa at next footswitch press. In turn, this turns on either transistor Q2 or Q3. Q2 allows clean geetar through, Q3 allows feelthy distorted geetar through. Because the clean and effected signals are always present at the switching points A and B, and fets not being perfect at the fully off game, you can get bleed-through in bypass.

Not all B*ss pedals use this simple an arrangement but its always the same principle.

[no one ever]

This may help better. Switching elements are in red. Can you work it out ?



Q5 and Q6 are a bistable, and the conductive state of the transistors changes when the footswitch takes their base caps low. This toggles the outputs (points C & D) from low to high and vice versa at next footswitch press. In turn, this turns on either transistor Q2 or Q3. Q2 allows clean geetar through, Q3 allows feelthy distorted geetar through. Because the clean and effected signals are always present at the switching points A and B, and fets not being perfect at the fully off game, you can get bleed-through in bypass.

Not all B*ss pedals use this simple an arrangement but its always the same principle.

thank you! much obliged.

[Mark Hammer]

First, look at this:  http://ampage.org/hammer/files/dodswitch.gif

DOD uses a different circuit to do the flip-flopping, but the basic premise is the same: turn one FET on while you turn another off.  You'll see that the FET/cap-to-ground/series-resistor is the same in DOD, Boss and other pedals.

One important thingto note is that the number of FETs required to bypass something depends on the nature of the effect itself.  Whenever the effect is produced by combining dry/clean signal and some form of modified signal (delay, phaser, flanger, chorus), it is extremely common, if not universal, to see use of a single FET for disabling the wet signal.  The dry signal passes on from input to output with no impediments, or any differentiation between effect vs bypass.  Here, you will see the series-resistor/cap-to-ground/FET combo coming out of only ONE side of the classic discrete flip-flop that Boss uses.  When it's a fuzz, though, you need to provide bypassing in a few places, and one wil usually see at least two FETs, and both sides of the flip-flop being used.  As the DOD gif shows, it is quite possible to have the same flip-flop actuate several FETs in each state (flip vs flop), and accomplish more complex this-vs-that switching.