Dual effect 3-way switch

[Grubb]

Hi folks, I'm sure someone here can point me in the right direction. I'm designing an effect for someone that has both a boost and an octave up. I'd like to have a toggle that allows switching between 3 modes: boost, octave and octave into boost.

I tried to work this out with a diagram of a 3PDT but I'm not smart enough

Thanks if you are able to steer me straight

 

[Bricksnbeatles]

Too late to draw something up, but I’ll give you a hint: 4pdt

If I get a chance tomorrow I’ll draw something up, but someone else will probably have explained it better than I could before I get the chance

 

[JTEX]

Something like this, maybe?

 

[Grubb]

Thank you. It always looks so simple after someone explains!

Edit: But actually I don't understand the DP3T part. Is this any different to a DPDT on-on-on?

 

[Feral Feline]

Oh FFSFF!

The other day, like within the last week, I stayed up 'til 7am trying to get the routing for this very sort of thing sorted out on DIYLC (7-9 hrs?).

I wanted:
Circuit A
Circuit A > B
Circuit B


I tried 3PDT on-on-on briefly, then thought it'd have to be 4PDT on-on-on, then tried it with 4PDT on-off-on with my own "on-on" jumper-arrangement... AAUGH! GOOD GRIEF!

Taking JTEX's schematic (Thanks @JTEX!), I've gone back to my DIYLC doc to fix what I thought was impossible without resorting to relay-switching:





Fixing this diagram up to present here, I realised what I was doing wrong the other night: I was only looking at the middle position even when I was working on the first or third position, which meant that Lugs 1&2 were ALWAYS connected whatever the lever-position ...

Once again, I encourage others not to work during sleep-deprivation. It's now nearly 5am and I've spent wayyyy too much time on this damn diagram, again!




Oh, and to try to clear up any confusion about the circuit switchcraft for those unfamiliar with on-on-on or DP3T...:
A "Dual-Pole Dual-Throw" (DPDT) is technically only on-off or on-on. A switch that has three positions — on-off-on or on-on-on — is a three-throw switch: SP3T, DP3T, 3P3T, and 4P3T...
However, most often on the forums people refer to any Dual-Pole Switch as a "DPDT"; There really isn't such a thing as a "DPDT on-on-on".

Same for the 3P3T and 4P3T, most people just refer to them as a dual-throw, whether they are or not.

 

[Bricksnbeatles]

Oh, and to try to clear up any confusion about the circuit switchcraft for those unfamiliar with on-on-on or DP3T...:
A "Dual-Pole Dual-Throw" (DPDT) is technically only on-off or on-on. A switch that has three positions — on-off-on or on-on-on — is a three-throw switch: SP3T, DP3T, 3P3T, and 4P3T...
However, most often on the forums people refer to any Dual-Pole Switch as a "DPDT"; There really isn't such a thing as a "DPDT on-on-on".

Same for the 3P3T and 4P3T, most people just refer to them as a dual-throw, whether they are or not.

I don’t think that’s quite correct, but I may be wrong. Even mouser has three position dpdts listed. Throws refer to the number of contacts per pole that aren’t the common. I don’t know that I’ve ever seen a dp3t toggle switch, but slide switches and rotary switches for sure.

 

[Robert]

"Throw" isn't technically the same as "position", otherwise a SPST couldn't exist either. (Because a one position switch is just a jumper wire)

According to a quick Google search:
“Pole” indicates the number of circuits that one switch can control for one operation of the switch. “Throw” indicates the number of contact points. NO and NC contacts are single throw. Changeover contacts are double throw.

 

[Robert]

Regardless of terminology, that's a cool little circuit above.

I might have to work up a little breakout board to make wiring that up easier.

 

[JTEX]

On-On-On switches used to confuse the hell out of me, but I've used them enough that they eventually started to (mostly) make sense. Schematically, they're the same as a regular DPDT: two electrically independent halves that can swing one way or the other. They just have an additional center position where one side goes one way and the other goes the other way.

Yes, the DP*T terminology can be confusing. I usually just call them On-On-On, but I've seen them listed as DPDT (with On-On-On function), DP3T, and even SP3T (!).

Indeed, you can make an SP3T (a 3-way selector, to be clear) out of an On-On-On, with one external jumper wire:

 

[Bricksnbeatles]

Something like this, maybe?
View attachment 44555

Wouldn’t you likely want a switch at the input of the boost to prevent it from splitting and loading down the signal when only the octave is selected? That’s why I thought you’d need a 4pdt (because it’s very difficult if not impossible to find an on-on-on 3pdt)

 

[JTEX]

Wouldn’t you likely want a switch at the input of the boost to prevent it from splitting and loading down the signal when only the octave is selected? That’s why I thought you’d need a 4pdt (because it’s very difficult if not impossible to find an on-on-on 3pdt)

Presumably you have some sort of buffer at the input of the circuit that can easily drive 2 loads.

 

[Bricksnbeatles]

Presumably you have some sort of buffer at the input of the circuit that can easily drive 2 loads.

If it’s being designed into the circuit, yes definitely. If it’s a utility breakout board though, it might be better to make with a 4pdt so it can be a quick drop-in for whatever circuits someone may be using it for

 

[Feral Feline]

More switchery fun...





I think this is supposed to be a DPDT On-On-On acting like a 3PDT by jumpering pins 3&5...

 

[JTEX]

More switchery fun...


View attachment 44622


I think this is supposed to be a DPDT On-On-On acting like a 3PDT by jumpering pins 3&5...

Yes, same thing as my diagram above, just drawn in a more svastika style