Your favorite way of bypassing without a 3PDT

[Mugshot]

with a 3PDT, i always use the grounded input on bypass method.

[tiges_ tendres]

The vandal-resistant switches are usually sort of set back into the bezel so much that they can't be stomped accurately. That's part of the vandal-resistance. 

Ive seen some that are just slightly proud of the surface which would work ok, but they were around $12 each, and a little long for stomp box purposes.

[askwho69]

bump

I've tried the cd4053 setup on geofex, which works well, but I'd like to explore other setups as well for the best performance with the least amount of complication.

did you perfed it? or your have layout? if so can you please share it to me please? askwho69@yahoo.com

[newfish]

Standard DPDT switch without an LED for me.

More room for pots and such on smaller boxes.

As for status indicators, well, since all I make is 'Fuzz / Drive / Gain etc', you'd have to be deaf to not realise if your boost-a-rama-fuzz-4000 was bypassed.

Am a recent fan of the older Big Muff style half-bypass. 

DPDT switch, just wired so that the input is always connected to the PCB - it's just the output that is switched.

Providing your circuit has a high enough impedance to leave the top-end in place, I'm happy to use that if I'm feeling all fancy-like, and need an LED.

Cheers!

[Hides-His-Eyes]

Standard DPDT switch without an LED for me.

More room for pots and such on smaller boxes.

As for status indicators, well, since all I make is 'Fuzz / Drive / Gain etc', you'd have to be deaf to not realise if your boost-a-rama-fuzz-4000 was bypassed.

Am a recent fan of the older Big Muff style half-bypass. 

DPDT switch, just wired so that the input is always connected to the PCB - it's just the output that is switched.

Providing your circuit has a high enough impedance to leave the top-end in place, I'm happy to use that if I'm feeling all fancy-like, and need an LED.

Cheers!

Or better yet, stick an op-amp buffer on the front so you KNOW it's high enough...

Something like a big muff definitely does NOT have high enough input impedance in my opinion.

[edvard]

...

Also, it looks like you have to design in certain low-side/high-side considerations when using BJT's compared to FET's.

Not sure what that means.

Are there any articles or threads that explain more about BJT switching?

I've never seen any. The main requirements are a very low source resistance, and very high load resistance (ideally infinite at DC, although 100k seems to be OK without causing DC jumps)

I think your last reply was the answer to the one before.
So you need a low impedance going in to the switch, and a high impedance (like a buffer) after?
I'll have to have another look at your circuit and do a little breadboarding...

[blueduck577]

The main requirements are a very low source resistance, and very high load resistance (ideally infinite at DC, although 100k seems to be OK without causing DC jumps)

This seems astonishingly simple.  How come we usually see FET switching instead of BJT switching?  Is there any disadvantage to using BJT switching (other than the constraints above)?

[knealebrown]

RE: bypassing with relays ive never had any problems with my relay based bypass box popping audibly or anything.



i essentially just connected the signal to the correct places and used a DPDT switch to change the state of the relay by closing the circuit when the 9v was applied. Then the other lugs on the switch can be sued for a status LED.
I know i should probably run a diode or cap or something on the poles but i dont know why people dont use this method more, am i missing something?

[askwho69]

HI ALL! anyone has a pcb of RG's cmos switch? i perfed it last time and it was a BIG HEADACHE! heheh anyone has it? thanks i advance

[merlinb]

So you need a low impedance going in to the switch,...

Yep. Output of an opamp is ideal.

... and a high impedance (like a buffer) after?

Yep. You can seen in my schem that the level pot has a DC blocking cap, so the load resistance is more-or-less infinity at DC, so there can be no DC drop across the transistor and hence no pops and clicks.

This seems astonishingly simple.

That's exactly what I thought when I first saw it, briefly mentioned in the Stompbox Cookbook.

How come we usually see FET switching instead of BJT switching?

'Cause people don't like to stray far from the familiar apple tree.

Is there any disadvantage to using BJT switching (other than the constraints above)?

In this application, BJTs work equally as well as FETs, or even better, since BJTs have a small, well defined turn-off voltage. As long as you don't mind obeying the requirements of low source resistance and very high load resistance (mainly applicable to opamps circuits) then knock yourself out.

[brett]

Favourite?  A bare wire on the floor connected to the output of the pedal, and a bare input wire on the sole of your shoe.  Stomp for bypass.
Favourite, silliest, not best. 

[darron]

i've never done it, but you could try optical bypass with a couple of LED/LDR.... when lit i have LDRs that go to a K ohm or two, and dark several M ohm

[brett]

Hi
Darron's idea is excellent.  I've used those 6 pin DIL optocouplers (6N25?) in a range of applications.  They make fast and smooth switches (compared with relays) and compared with 4000 series CMOS switches are smaller and easier to handle.
cheers