help designing and building a loop please

[alex]

okay, here's what I want to do and why

I have a Boss DD-3 modded by Robert Keeley to have an effects loop. What I want to be able to do is switch effects in and out of the DD-3 loop and my regular signal path. So, have the desired effects (its a flanger) in a loop, and then be able to switch that loop between the DD-3 loop and my regular signal path. I think its possible with a Boss LS-2 in either the A  B or A+B mix/bypass modes, but I've never used one so I'm really not sure.

At my immediate disposal are a 3PDT and a couple of DPDT stomp switches, plus a housing and jacks, soldering iron and skills

any ideas?

[expanoncolin]

A very good idea.

There are a couple of ways to do this, none of them are ideal but I can't think of a better way (there may be some more clever way I am not thinking of).

So assuming you want the flanger first, you'd want to set up one set of poles/throws on the 3pdt so that the pole (Center lug) was sent to the delay in, and the two throws were either the flanger out, or straight to the input.  If you weren't worried about true bypass, you could simply make a permanent wire from the input to the flanger input.  But, if you want TB, you're goignt o need to take another pole from the input whose throws are the flanger, and direct to the throw on the other switch that connects to the "input" throw on the other row of poles/throws.  So basically, you have a simple true bypass loop-input connected to one pole, delay input conneted to the other pole, 2 throws connected together at the top, one throw at the bottom sent to flanger input, the other from flanger output.  Now for the delay FX loop.  You could integrate this into the 3pdt, but it would not be TB.  You would want to make it so that in the "upper" position (IE, w hen the flanger is in your regular signal path), the fx send is connected to nothing, and when the flanger is out of the signal path, the fx send is connected to the input, with the flanger output permanently wired to the fx return.  This is not ideal, ideally, you'd have a 4pdt.  Or, you would not wire the signal path loop TB, and make this part TB.

Good luck...

-Colin

[alex]

suffice to say i am confused and a little bit daunted by this explanation, but i know for sure that this part won't work:

the fx send is connected to nothing, and when the flanger is out of the signal path, the fx send is connected to the input, with the flanger output permanently wired to the fx return.

if the FX send is connected to nothing, the delay won't work properly, so when the flanger is in the regular signal path, the DD3 FX send and return have to be connected to one another

also: i'm not normally over-the-top concerned with TB, but I'd much rather have it in this project as the bypass on my FL-9 is pretty poor (when it's in the dd-3 loop it kills signal and i lose repeats)

i may be in over my head with this

[expanoncolin]

Ah... That's fair...  So you will need to do two switches.  One of them as before, to select whether the flanger goes before the delay, or is bypassed, and one to select whether the flanger is in the delay loop, or the delay loop is straight up bypassed.  Not very elegant.  For a better system, you'd use an electronic switch like the 4066 or 4016.

-Colin

[alex]

i am not at all opposed to using an IC switch, though i would have to rig up a point-to point board or something (a couple of years ago i could have etched a PCB, but i don't have access to that at school anymore)

would it be at all possible to ask you to draw up a simple circuit using one of those IC's?

[expanoncolin]

i am not at all opposed to using an IC switch, though i would have to rig up a point-to point board or something (a couple of years ago i could have etched a PCB, but i don't have access to that at school anymore)

would it be at all possible to ask you to draw up a simple circuit using one of those IC's?

They are very very easy to figure out how to use.  Take a look at the datasheets.  Essentially, you have 4 SPST's, each controlled by a pin.  Imagine having a (essentially) infinite number of SPSTs, all controlled by a single SPDT.  With the SPDT up, some SPST's are on, others are off, with it down, the SPST's all switch states.  This is what you can do with electronic switching.  Because you can take two SPST's and make them share some input with two outputs and make their control pins opposite, you basically have an SPDT.  Since you can make as many poles as you need, you can have a 1000PDT if you really need it.  This is kind of what we need here.  We need a switch with four poles.  When the control switch is up, the input is connected to flanger input, the flanger output is connected to delay input.  The FX loop is wired straight through.  With the control switch down, the input is connected straight to the delay input, and the FX send is at flanger in, FX return is at flanger out.  We essentially have a 4pdt here-5pdt if you want an LED to top it all off. Some things to consider with the 4066 switching is that you should have a .1uf capacitor from the power supplies of all of them straight to ground.  The simplest control switch would be a DPDT, with one set of controls on one pole, and the other on the other pole, with throws being opposites-V+ and ground.  If you use pullup resistors, you can just have an SPDT with the center lug being ground, top and bottom lugs being the control's.  You can also use a spare 4066 switch and use an SPDT, but then you are getting a little complex and mildly silly!

Some notes on 4066 switching, with some unnecessary (in my mind) logic on the control:
http://www.geocities.com/thetonegod/swi ... tches.html

-Colin