Your favorite way of bypassing without a 3PDT

[mth5044]

What is your preferred way of bypassing a circuit without using a 3PDT switch? I've seen relays, FETs, CMOS, stuff I don't understand, millenium bypass and more!

So maybe say what you use, why you like it, and perhaps a schematic?

[trjones1]

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.

[slacker]

For true bypass, if the effect needs a LED I use a DPDT and millennium bypass, if not then just a DPDT.
If you don't care about having true bypass then this but with a buffer in front to stop tone sucking works well, or use a DPDT if you want a LED.

[trjones1]

I would happily use a dpdt with millennium if I knew of a truly reliable switch to use (i.e. more reliable than the 3pdt blues).  Any suggestions for that?  Thanks in advance.

[slacker]

I've used the alpha ones smallbear sells without any problems.

[liddokun]

I've used the alpha ones smallbear sells without any problems.

+1 on the alpha switches. starting building on these switches (only because they were less expensive) and they are very reliable.

[Taylor]

I use relays. True bypass but only 2 wires to run. What's especially cool is that with a non-latching relay, if your board loses power the pedal automatically goes into true bypass regardless of the switch's position.

[Pigyboy]

I use relays. True bypass but only 2 wires to run. What's especially cool is that with a non-latching relay, if your board loses power the pedal automatically goes into true bypass regardless of the switch's position.

Hey Taylor,
Can you elaborate on your method with the relays. Are you using a click-less from AMZ or Jack Deville or something of your own design? I have 2 of the AMZ's with the small board, relays and the pre-programmed chip and have yet to use them.
Thanks,
Chris

[Hides-His-Eyes]

I use relays. True bypass but only 2 wires to run. What's especially cool is that with a non-latching relay, if your board loses power the pedal automatically goes into true bypass regardless of the switch's position.

Best way to isolate relay from power supply (avoid the 555 effect?)

[Taylor]

I don't have a schem handy but I basically use a pretty standard transistor relay driver. The SPST stomp switch (actually usually a DPDT Alpha since they're cheaper and smaller than the SPST stomps available) switches voltage to the base of a transistor - when the base is high it grounds the relay. A cap from collector to base slows the turn-on to avoid pop. RG has lots of good information on geofex.com about relays, and some more sophisticated stuff than I am doing.

I haven't really had any trouble with popping from current spikes in the ground rail, if that's what you mean by 555 effect.

[merlinb]

I prefer to use series BJTs to do the switching. (I use a lot of opamps and always use buffered switching, not true bypass).
The same thing could be done with FETs, but BJTs are cheaper and more widely stocked by small dealers. The switching is pop-less and you can have any number of switched elements and LEDs controlled by a single SPDT. Example:
http://i81.photobucket.com/albums/j207/merlinblencowe/DM160/EB91pedal.jpg?t=1289044348

[slacker]

That look interesting, I'll have to give it a try.

[edvard]

Would a standard flip-flop do for controlling the BJT arrangement?
Also, it looks like you have to design in certain low-side/high-side considerations when using BJT's compared to FET's.
Are there any articles or threads that explain more about BJT switching?

Intriguing, indeed...

[roseblood11]

I use the improved version of the millenium bypass that connects the input of the pcb to ground.

[merlinb]

Would a standard flip-flop do for controlling the BJT arrangement?

I don't see why not.

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)

[trjones1]

I use the improved version of the millenium bypass that connects the input of the pcb to ground.

Aha, I was wondering if you could ground the input with a millenium setup.  Do you have a link to a schematic that shows this setup?

[tiges_ tendres]

I've been looking for some of those vandal resistant elevator switches, but couldn't find any that seemed like they would work for our application.  I know they are out there, I just have had zero luck finding them!

[Taylor]

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. 

[Hides-His-Eyes]

If you can put up with his condescension for long enough to ask, I know mictester on The Other Forum uses them, and could probably tell you which he uses.

[g-sus]

I used millenium bypass 2 today for adding leds to desktop effect box which had just dpdt toggle switches. It's small, works fine and is very easy to build.