Bicomp wiring diagram?

[jensvjakobsen]

Hi there everyone,

I bought the PCBs for the Orange Squeezer and Ross Comp from Generalguitargadgets.com with the intention of building both of them into one box, like Analogman's Bicomp. I have searched the web for days without results and tried at the best of my abilities to "translate" the GEOFEX DPDT + millenium to 3PDT, without luck.

Of course, the biggest problems with this project is figuring out how to connect the effects in series (from one 3PDT to the next), connecting both to the same power source with separate switches.

J.D. from GGG said that both could be powered from the same battery/DC-jack.

Does anyone have or know the whereabouts a wiring diagram with both of these effects, using 3PDT and LEDs and all? Any help at all would be greatly appreciated.

Thanks
Jens

[Mark Hammer]

What you want are two 3PDT switches.  One will switch between whatever is in the box and a straight-wire bypass.  The other takes its feed from the first switch, and selects between two alternate sets of input/output leads: one from the OS and one from the DC.  So, instead of having one set of contacts with a straight-wire connection as on your first stompswitch, those two contacts now go to one of the circuits.

Make sense?

[jensvjakobsen]

So what you're saying is SW1: On/Off and SW2: RC/OS?

That would be excellent, but I still don't know how to wire the two together...

BTW the diagrams are:
Orange Squeezer: http://www.generalguitargadgets.com/pdf/ggg_osq_vol_lo.pdf
RossComp: http://www.generalguitargadgets.com/diagrams/geo_d&r_comp.pdf (on page 5)

[Mark Hammer]

This picture shows how to wire up a DPDT switch:

Wire up the main switch just as shown, except that what you see going to "effect in" and "effect out" here will go to lugs 2 and 5, respectively, of the second switch (we'll say 1 goes to 2, and 4 goes to 5).    So you either go directly from input jack to output jack with that primary switch, or your signal gets routed to a second switch.  That second switch now selects between the OS input/output leads on terminals 1 and 4, or the Dynacomp/Ross leads on terminals 3 and 6.

It's two cascaded (nested, actually) binary decisions: what's in the box or go straight through?  if what's in the box, this one or that one?

You will likely want status LEDs for each switch since compressors are not the easiest things to detect as on or off.  Here is a wiring diagram: http://www.diystompboxes.com/pedals/images/3PDTwiring.jpg

Note that those three "columns" of contacts are essentially interchangeable.  There is nothing magical about 1-3 vs 4-6, vs 7-9.  You could use 1-3 for LED switching, or 7-9, or 4-6 as shown.  The diagram shows a 1k resistor in series but it could actually be a variety of other values, depending on LED brightness.  If it's a normal LED and the chassis is not dark, then 1k is probably called for.  Dark chassis with greater visual contrast can tolerate a little more resistance like 2.2k.  "Superbright" LEDs can tolerate higher resistances.  I've used as much as 18k on some of mine.  Limiting current draw by means of that "current-limiting resistor" prevents the LED from burning out, but at the same time reduces brightness and also battery drain.

Which brings us to a critical choicepoint.  You probably want to use an LED to designate which compressor is on, but also need another LED to indicate whether the pedal is in bypass mode or not.  The more LEDs you have on, the more current you draw.  Even when you bypass compressor A *and B, they are still drawing curent from the battery.  So, if you were to use one LED for on/bypass, and two additional LEDs to indicate comp A vs B, you have two circuits, and 3 LEDs drawing power from the same battery.  Do you have an uncle named Ray Ovac or an aunt named Mallory Duracell who likes you a lot?  If not then plan around using a wallwart.  If you want to be able to use the pedal in battery-only mode, then you need to reduce current consumption by either using superbright LEDS and deliberately running them dim, using a toggle to select visually between comp A or B (i.e., forego footswitch change), or both.  Certainly having two garden variety LEDs on can run as much current draw as some effects, so you are essentially powering 3 effects (the LEDs, the comp you are using, and the comp you aren't using) from one battery.

People have asked here about being able to switch the power off via the bypass stompswitch.  It is not recomended because you get popping or sluggish start-up, neither of which are pleasing to hear.

[jensvjakobsen]

Thanks

I'll start working on that ASAP

[mcasey1]

I bought a "Juicer" from Mike a while back, and since getting into DIY, I wanted to expand the parts on the board to cover the Ross side as well.  The board from the Juicer is the same as one used in a BiComp, so it has spaces for all the Ross parts.  I just dont know how closely his Ross circuit follows the original for which schematics are provided.  Does anyone have any info on this or could anyone contact me privately and let me know?  I know Mike is worried about other people getting his board layouts and ripping him off.  I dont want that to happen.

Thanks-Matt