True Bypass Box Grounding & Power Jack Issue?

[formerMember1]

Hi,
I am building a True bypass box using the wiring diagram from Aron's main page.
Click on the below link, then click on "Check out the 3PDT switches" then click on Loop Box.
  http://www.diystompboxes.com/pedals/index2.html

Do i send the LED's + or - to ground?  I know in NPN pedals you send the - to ground and in PNP pedals you send + to ground but what about a True Bypass Loop Box?  <<<<<<<<<After thinking about it, I guess it is my choice, right?>>>>>>>>>>>

I am using 3 mono jacks, one LED, a stereo jack, and a 3PDT, and a power jack.

Is it possible to just wire it up NPN so that way i could use my "normal" power supply?

Should I use shielded wire anywhere?  Are Loop Boxes known to have "HUM" problems?

I am using the pedal to bypass my buffered Korg tuner.

thank you

[Mike Burgundy]

Have a careful look at the drawing you're referring to, and think about what it does carefully: the LED circuit is isolated from the switching bit. Okay, they share a ground connection, but you could also choose to have the battery circuit completely isolated from signal ground. It would still work. This way it's just easy to wire.
So, if the battery circuit is connected *at just one point* to signal ground, there is no way for the rest of the circuit to "know" wether the other battery terminal is at a higher, lower, or same potential, because there's no connection between that other terminal and the circuit.
That means you can hook up that battery just the way you like - just make sure the LED is pointing the right way (it only works with the current flowing in one direction) Wiring it up NPN doesn't make sense here, since there are no transistors - I think you mean negative ground - and the circuit as shown is just that. The "arrow" designates the way current wants to flow, from + to - .

There IS a catch though. If you are using a wallwart or some tother kind of external supply, and youre powering more than one box of off this, you HAVE TO make sure the grounding scheme is correct. It will work fine as shown, but if you wire it in reverse you'll short out the powersupply causing some smoke in the process. The other pedals will have a ground connection connected, and will also connect that (negative) ground to the signal grounds on the bypass box. If the bypass box uses positive ground, it will connect positive to negative, hey presto. You can avoid this by isolating the switching bit from the signal bit as mentioned above.

If you are using a nice metal box, wire neatly and use short connections, there is no need for shielded wire. It's always good pratice to use the stated thingies, shielded wire comes in handy on high-gain circuits and circuits with clocks, mostly on the inputs, to shield from signals *inside* the box.

Be aware that a lot of (metal) power jacks connect their sleeves to the box, while standard power supply connections for pedals have a positive sleeve. This would also short out the powersupply!! Either rig up a cable reversing the connections, and wire the connector with the sleeve to (negative) ground, and never get that cable confused, OR isolate the connector completely from the box.

*whew* Still here?
Here's the easy summary:
-use a metal box
-use negative ground
-make sure the powersupply jack is isolated from the chassis (the box)
-use neat, short wiring
-use neat, well-flowed, shiny soldering
-connect the box main ground to the input jack's ground, and rely on the metal box to connect all other grounds (unless you have isolated(plastic) jacks, then conect all grounds to the input ground)
-consider yourself welcomed to the wonderful world of DIY

[formerMember1]

thanks for the reply and help, 

*I am using a metal box,(1590B)
*I did mean negative ground, (thought NPN was the same thing  )
*THe power supply jack is plastic so i guess it is isolated,
*neat short wiring with great solder joints is my specialty,
*my jacks(input- stereo, and rest are mono) are switchcraft, metal ones) <<<<<<<<I have a wire running from the input jack's ground, to the "guitar in" jack's ground then a wire going to "to amp next pedal" jack's ground, then a wire going to effect out ground.)  just like the drawing....

I have the LED's positive leg soldered to the middle lug of the 3PDT switch, and the negative leg soldered to "to amp next pedal" jack's ground, with a 10K limiting resistor.

My power supply is a Voodoo Labs Pedal Power 2, according to Digital Music INC...(makers of the power supply  )  I don't have to worry about smoking the power supply or other pedals.  THe reason they say this is true is becuase the 8 power jacks are isolated from each other.

BUT, i am not taking that for granted, i never knew this could happen.   


AT this point i have everything wired like the diagram, except i didn't wire a battery in  yet or power jack. 
I have all the lugs on the power jack empty, the top middle lug of 3PDT switch empty, and the RING of the stereo jack empty.

<<<<<I don't want the battery option only a power jack option>>>>>>>>>>>

BUT, Are you suggesting that i hookup a battery to the pedal first, to see if i got everything wired up right, then if all is well, wire up the power jack and remove battery clip?

I am still confused about how to wire the power jack into this pedal.  I already wiring a power jack into a Rangemaster pedal i built just recently, but that pedal was PNP and reverse polarity, and after a while i finally got it w/ help from Korgull. 

I think i am gonna go wire up the battery in there and hope it works right, then if works i will post up for some help with the power jack. 

thanks alot for the help, i understand the drawing better now, instead of just painting by number. 

[Mike Burgundy]

AFAIK, the pedalpower (my guitarist has one too, good stuff) has a 7809 type regulator, which should be protected internally against shorts - it just shuts down, without frying. That's what mine do, anyway (DIY Spyder). a pedal without polarity protection can still be fried by hooking it up wrong-way-round. Even one *with* polarity protection (usually one diode in commercial pedals) can stop working until you replace the diode.
You don't have to hook up a battery first (although at times it's a good way of making sure everything works, especially if you have hum when using a wallwart), just make sure no DC terminals are in contact with the chassis. a multimeter will help if in doubt.

[formerMember1]

hey MIKE

Got one question for ya.  I have everything wired up but the power jack.  If i am looking at the jack with the big lug on bottom, i guess i would do the following:

top lug: goes to top lug on 3PDT switch   ?
bottom lug: goes to ring of stereo input jack  ?

I am confused about what lugs on the power jack do what? 

i am using the plastic power jacks from smallbear,

http://www.smallbearelec.com/Detail.bok?no=93

i don't need the option of a battery...

here is the link again to the true bypass box:

Click on the below link, then click on "Check out the 3PDT switches" then click on Loop Box.
  http://www.diystompboxes.com/pedals/index2.html

[KORGULL]

I am confused about what lugs on the power jack do what? 

Something to remember about the power jack is that it has a NC (normally closed) switch in it, so the two smaller lugs are connected (shorted) until you insert a plug - which then breaks that connection.
I think if you will not be using a battery at all, you probably only need to connect the one power jack lug to your circuit.
Use the lug that doesn't get its connection broken when the power plug is inserted (top lug).
The other lug usually gets the battery+ wire connected.

top lug: goes to top lug on 3PDT switch   ?
bottom lug: goes to ring of stereo input jack  ?

That sounds right if by "top lug of 3PDT" you mean the top center lug in the diagram for the loop box and "bottom lug" = power jack ground lug

[formerMember1]

thanks KORGULLll!!   

Power jack certainly works now.  My rangemaster works great/right too. ( "fixed">>>power is switched on when cord is plugged into input jack)

I know i had asked alot of questions the past few days/weeks about power jack problems and thanks for helping me solve the problems.  I do appreciate the help and time.

At least, I now know how the power jack works.  Instead of just following a diagram i now understand it, because i had so many problems and you graciously gave your time, even though i sometimes described my dilemma confusingly. <<< (I always had/have trouble writing my thoughts into words on a computer screen.  )

thanks 

[KORGULL]

No problem. It helps me get a better grasp on this stuff too when I force myself to really think about it and write/type it out.