Non-true bypass, buffered switching.

[msurdin]

Hey everyone,
Its been a long time since ive been on here, and I am trying to get back to building some things.
I had some questions on non true-bypass switching, and adding a buffer to a build.
Ive had much success building some of the kits out there, and i wanted to try adding one of the small buffer boards into some of my pedals, while removing the true bypass.
If i understand correctly, the buffer is always on, the dpdt just activates the effect in the cornish style effects, or is there a second buffer after the activated board?

Can both boards run off of the single 9v power?
Are there any layouts for anything like this around? Ive been unlucky in my search.
Does the buffer change the impedance, as you always read cornish rant on about, or is that a whole other animal?

thanks for helping!

[GibsonGM]

Hi, this will probably give you some info and ideas!

Nice read about how it's done, and I'm sure you'll unscramble JFET switching enough to do what you want:  http://www.geofex.com/Article_Folders/bosstech.pdf

[R.G.]

You probably also would enjoy http://www.geofex.com/Article_Folders/bypass/bypass.htm

[amz-fx]

Hey everyone,
Its been a long time since ive been on here, and I am trying to get back to building some things.
I had some questions on non true-bypass switching, and adding a buffer to a build.
Ive had much success building some of the kits out there, and i wanted to try adding one of the small buffer boards into some of my pedals, while removing the true bypass.
If i understand correctly, the buffer is always on, the dpdt just activates the effect in the cornish style effects, or is there a second buffer after the activated board?

Can both boards run off of the single 9v power?
Are there any layouts for anything like this around? Ive been unlucky in my search.
Does the buffer change the impedance, as you always read cornish rant on about, or is that a whole other animal?

thanks for helping!

Here are some examples of how a buffer can be used with another effect. The #4 and #5 examples are probably what you are seeking. In the #4 example, the buffer is always on and its input is the new impedance for the pedal. In the #5 example, the buffer is not always on as it is only buffering signal when the effect is bypassed, so the effect circuit should behave exactly like it did before the buffer was added.

http://www.muzique.com/schem/buffmod1.htm

This would apply to any buffer, whether on a pcb or stripboard. A properly filtered and grounded buffer should not be a problem running off the same power as the fx.

Best regards, Jack

[POTL]

hi everyone
I do not want to clutter up the forum with new useless topics, so I will try to revive the

I came across such interesting as the pedal Wampler Decibel + and Mi Audio Boost n Buff
Wampler Decibel +

and Mi Audio Boost n Buff


I was attracted by the fact that each pedal is essentially the effect of 2, I wondered to understand how you can implement this business practice
guinea became MXR Micro Amp
Why it? Because it's a legendary classics like Mustang, Jack Daniels or Marshall
moreover, the second half of the Op Amp can be used to buffer JHS Black Box


I took a chance and drew a diagram (this is my first, so strongly do not beat)
I understand that this is more like a clone of Ripley from Alien: Resurrection than circuit 

yeah I know that the first switch must be turned through 180 degrees - a now near at hand only without a home computer operating software
Can you suggest how to get this beast to work (I'm more than sure that there is an error)

[PRR]

The TLo7x can buff or boost *depending how you connect stuff*.

Switches can change how stuff is connected.



When the lower (left) end of the NFB loop is broken, the opamp goes unity gain. Buffs! When NFB connected, gain happens, boost!

[POTL]

The TLo7x can buff or boost *depending how you connect stuff*.

Switches can change how stuff is connected.



When the lower (left) end of the NFB loop is broken, the opamp goes unity gain. Buffs! When NFB connected, gain happens, boost!

Thanks, but it's not quite what I had in mind

I want to buffer could work with the booster, and without it, that is, that in the closed position has always had a booster and off using the toggle switch could choose what to use, true bypass or buffered

[amz-fx]

POTL,

That is what the circuit that PRR posted is doing.

When S3 is open the output is buffered.

When S3 is closed, the output is boosted.

The position of S3 is controlling the gain and effectively alternating between a buffered signal with gain of 1, and a boosted signal with the gain set by the Boost control.

Best regards, Jack

[POTL]

POTL,

That is what the circuit that PRR posted is doing.

When S3 is open the output is buffered.

When S3 is closed, the output is boosted.

The position of S3 is controlling the gain and effectively alternating between a buffered signal with gain of 1, and a boosted signal with the gain set by the Boost control.

Best regards, Jack

this is not exactly what I need
In fact, I need switch - true bypass/buffered
when the pedal is off I can choose what type of bypass use
when the pedal is turned on I get a booster


that is, I need to add additional circuitry to an existing effect and how the logic tells me - the buffer must be in bypass and shut off by a DPDT toggle switch.

[amz-fx]

Ok, you should know what you are looking for.

Here is a revised version of your original that simplifies the switching and adds a few needed components:

http://www.muzique.com/misc/dual1.gif

A single dpdt foot switch alternates from booster to buffer. You can use a 3pdt to switch the inputs if you want to isolate the two parts for some reason. Inputs will then need pulldown resistors.

Best regards, Jack

[POTL]

Ok, you should know what you are looking for.

Here is a revised version of your original that simplifies the switching and adds a few needed components:

http://www.muzique.com/misc/dual1.gif

A single dpdt foot switch alternates from booster to buffer. You can use a 3pdt to switch the inputs if you want to isolate the two parts for some reason. Inputs will then need pulldown resistors.

Best regards, Jack

Thank you tomorrow fix scheme and installed the switches and input and output resistors

[POTL]

Look like this

[amz-fx]

Still missing some parts. It is like this:



Best regards, Jack

[POTL]

I corrected power section.
DPDP switch toggles bypass mode. Bypass can be buffered or true.
3PDT it a footswitch

[bluebunny]

I can see what you're trying to do, but the DPDT is wired wrong.  The link needs to be between the top two lugs.  The middle two lugs connect to the "bypass" lugs on the 3PDT.

[POTL]

I can see what you're trying to do, but the DPDT is wired wrong.  The link needs to be between the top two lugs.  The middle two lugs connect to the "bypass" lugs on the 3PDT.

Hi, thanks for the reply
Can obhyasnit why the jumper should be on the upper contacts and not on the central, I need it for the understanding of the process)
If that helped me on the FSB picture attached below, suddenly someone else come in handy =)

[POTL]

I can see what you're trying to do, but the DPDT is wired wrong.  The link needs to be between the top two lugs.  The middle two lugs connect to the "bypass" lugs on the 3PDT.

Hi, thanks for the reply
Can obhyasnit why the jumper should be on the upper contacts and not on the central, I need it for the understanding of the process)
If that helped me on the FSB picture attached below, suddenly someone else come in handy =)

[bluebunny]

When the top switch (boost vs. not-boost) is in the "not-boost" position, then this is what the bottom switch (true vs. buffered bypass) is doing:

switch is "up" - bypass is a piece of wire = "true bypass"	switch is "down" - bypass is via the buffer

[POTL]

When the top switch (boost vs. not-boost) is in the "not-boost" position, then this is what the bottom switch (true vs. buffered bypass) is doing:

switch is "up" - bypass is a piece of wire = "true bypass"	switch is "down" - bypass is via the buffer

OK Thanks

[Agung Kurniawan]

I think Zoom Trimetal should be a good example for you. if you use this switch tipe + delayed LED indicator you may get silent switching