connect the components!! (pic included)

[chokeyou]

Hey guys! I still need to order my parts from smallbear (unless you suggest mouser is better) What I'm looking to create is a engage/disengage box to route my expression pedal to a number of effects (line 6 DL-4, Line 6 FM-4, and Boss DD-3 modified for exp. pedal input.

I have a few questions about the circuit i think you guys can help me out with.

1)whats the best way to hook everything up for what im doing (open this pic up in paint and draw me the lines, color coded would be nice   :wink:

2)would SPST switches work best for my application? (I dont need to worry about true bypass and such things, not even A/B style switching, just simple engage, disengage) if not, what kind of switch am i looking for? whats a good brand too?

3)what resistor value will work best for lighting my LEDs?

4)what is the best way to hook up a battery clip and power barrel and have the battery clip bypassed when the power barrel is being used?

I think I left you guys enough room so have at it!! thanks a ton!!

[donald stringer]

So what you want to do is #1 expression input inorder to select between one of three device inputs. An scroll up and down. Is that an mono input fromthe expression pedal? Isee three devices so an dpdt is out, but you could use two dpdt and  wire  it to the common of one dpdt and that would get you dl-4 on one side and upon depressing the dpdt the signal would be thrown to the common of the other dpdtand there you would have the fm4 on one side and thedd-3 on the other. If no one else gets back with you on an simpler solution. I would be glad to draw a picture of the idea and post it. I have been playing with ms paint lately. and I have all the symbols created to make it. I think you will probably get feedback from a no. of  people that will have varying ideas and there is always a simpler way. :idea:

nothing too too big or anything too too  small ever last too too long.

[chokeyou]

the input is a stereo input (arent all expression pedals?)

and yeah, i seriously dont want more than one thing going on at once with each switch getting pressed. it needs to simply engage and disengage the signal travelling through.

thanks

[Samuel]

Here's my super simple version, not 100% it would work, but might get the ball rolling.



The only trouble I can foresee is some kind of weird circuit interaction when you have more than one engaged. I don't know a ton about expression pedals so I have no idea if the circuit would ever move any serious amount of voltage into the expression pedal. Obviously using this version you can have multiple effects "accessing" the expression pedal simultaneously and I have no idea what would happen in this instance. Caveat emptor and all that.

Note that the two upper left lugs are connected...
ALSO - the line to the (-) of each LED should be flipped to the lower pole - I don't feel like redrawing it ATM....

Resistor value: I use 1k8s cause I accidentally got 100 of them once and have no other use for them. 470 ohm is the minimum (lower and you could easily pop your LED) and I've heard of people going up to and above 4K7 to save on battery life. Ohm's law will tell you how many milliamps your particular resistor will cause the LED to draw....I think 20 or so is the maximum?

[chokeyou]

lookin' good man! thank you for your input.

anybody else have any thoughts...or any thoughts as to if that'll work? i suppose theres nothing better than trying it out, but i need to order my parts and stuff first  :?  anyone know when smallbear will be back up and running?

or do you recommend anywhere else for this...i just think its easier ordering through smallbear.

[Samuel]

Man I musta been tired...:

Please note that two upper right lugs are connected (so that each pedal's expression input is just connected back to itself when the exp pedal is disengaged.

[Samuel]

Oh, and for stompable 3PDTs it's going to be either smallbear or Aron (sticky thread re: Blue 3PDTs). Only thing is smallbear is on vacation for the next week and a half or so, I don't know how quickly you were looking to get this stuff...

[Samuel]

The thing I posted above should work assuming that the pedal is sending some signal out of the tip and receiving a modified version of the same through the ring (or vice versa), with the sleeve acting as ground (depending on the jack you use, it should ground through the case, if this doesn't happen you'll need to just connect all of the sleeves together). If the expression pedal is set up in some other configuration you'll need to modify this.

Again my primary concern is that if two or more of the switches are set to "on" then the expression pedal I/O of one pedal will be connected to the others. I guess I can think of situations in which this could damage the other circuits (for example: expression pedal modifying voltage supply to one pedal, while another pedal is set up to not ever receive more than a couple of volts in the area of the expression circuit...) I'm sure these cases would be rare / not exist, but my ass was looking a little bare so I'm covering it.

[SoundTech]

Depending upon how the circuit you're hooking the expression pedal up is dealing with the expression pedal itself, paralleling 2 or more pedal's expression pedal connections may give undesired results.  If you only want to connect to one box at a time, then your 3PDT switches will work, but you have to turn of one before you turn on another.  The best way to do that would be to use CMOS switching and logic latching.  If you want to actually connect 2 or more boxes simultaneously, then a circuit that isolates the expression pedal and sends isolated voltages to each of the boxes would be ideal.

[chokeyou]

that sounds painful  

and i suppose there really isnt a way to do that mechanically, either.

[cd]

What Soundtech said.  If you want to use one stomp switch and alternate between the three pedals (say, every time you stomp on the switch, it cycles in order - 1, 2, 3, 1, 2, 3, 1, etc.) it will take a bit more work, but good thing is it will cost much, much less.  You can use all electronic switching (I would suggest JFETs or BJTs).

[chokeyou]

i have absolutely no idea how to even begin something like that, i'm thinking that might be a little too advanced unless i had a good schematic and walkthrough... maybe this is gonna be a lot harder than i had hoped.

[cd]

Then I'd suggest using a rotary switch (a SP3T will do it) and a BIG knob you can turn with your foot and the box with the jacks.  That's the easiest way to do it unless you want to stomp on/stomp off with the 3 footswitches.

[chokeyou]

yeah i absolutely need a stomp because i find myself dancing between effects A LOT. the more i think about it, i dont really need more than one engaged simultaneously so a switch that selects between 1, 2, 3, 1, 2, 3, etc seems fine. Plus i have an idea to hook the 3 LEDs up inside a clear fender amp jewel that lets me know what is selected, smaller format etc, cant go wrong i suppose. if anyone would like to help me out with that that would be excellent.