Stereo input jacks - why? and TB Loop Questions....

[trumpus]

So i build a single TB loop a little while back, and now i'm doing a few more for some friends.  This time, i was told that i should use a stereo jack for the input (from the guitar side) to control when power was on to the LED (only when something was plugged in).  I'm not sure how to go about wiring this jack (how is this any different than using a mono jack?).

It is my assumption that the power must somehow go through the jack, so that it can turn it "on and off" whether something is plugged in or not.

I've seen Aaron's diagram for wiring single and multiple loops, however i have been using a diagram from the guys at Loop-Master.com, which wires the 3PDT switch COMPLETELY different!

I have seen quite a few different ways to wire a 3PDT switch within the context of a TB loop box with an LED - as a newbie, i just don't understand why all the different ways work the same!

Here's what i want:

I need to make a single loop box with an LED a 9V batter and a DC jack

I also need to make a double loop box with an LED, 9V battery and a DC jack. 

What would be helpful is if i had ONE good, correct diagram depicting the correct wiring of each of these projects.  The diagram i have received from the Loop-master.com guys for the multiple loop box doesn't seem right to me.  The input is on the left and the output is on the right (backwards, as far as i can tell) - which is opposite from the original diagram i received when trying to put a single loop together.

I can post some pictures if it would help to illustrate...but i 'll have to get them up tomorow....

Brian

[ronh95]

I found the 'Offboard Wiring' .pdf file at Tonepad under FAQs to be extremely helpful.  It has a diagram for 5 or so scenarios, with/without true bypass, with/without LED, etc.  Good stuff for a newb like me.

http://www.tonepad.com/getFileInfo.asp?id=76

[trumpus]

Right, i've read that, but not exactly what i'm asking about!

Please read the post above!  I could use some help!

Brian

[scaesic]

yes, just like when you use a stereo input on a pedal and you insert a mono jack, it shorts pins 2 and 3 (connections to the jack sleave),
closing any circuit connected to them.

[Mark Hammer]

1) Once you plug into a stereo jack, the effect is "on" all the time.  This is why the bypass switch is called "bypass" rather than "off" - because it redirects the audio signal rather than shutting down the effect.

2) The status LED is not an indicator of power being disabled from the effect.  Rather, it is an indicator of the state of the signal - whether it is going through the effect circuit or "around" it.  The LED does not "depend" on the effect as such.

3) The 3rd set of contacts on the stomp switch that people use for indicator LEDs simply provide a path/interruption between the power source on the effect circuit board and an LED off the board.  To use the stompswitch, simply connect an appropriate value resistor to the V+ point on the circuit board, and run THAT to the appropriate lead on the LED and then to ground.  The extra set of contacts can either be used to open/close the contact between V+ and the resistor, the resistor and the LED, or the LED and ground.  Whichever one yuo choose will not matter other than in terms of convenience to you; they are electronically equivalent.

4) Make sure that the pair of contacts you use on the switch (from the 3 available on the 3rd set of contacts) is on the same side as the effect in/out leads, so that the power is applied to the LED when the effect is engaged.

5) The value of the resistor will depend on the brightness of the LED.  If it is a so-called "garden variety" red LED with a brightness of 500 millicandles (mcd) or less, then a 1k resistor will generally be called for.  If it is brighter than that (and superbirghts can easily exceed 6000mcd!), then less current is needed to provide similar brightness, and you may need a larger value resistor like 4k7, or ven 10k or 18k.  The general idea is to reduce the current drawn by the LED so as to conserve battery life, while making sure it is as bright as you need it to be under your normal operating circumstances.  In some respects, sticking a trimpot in the circuit to adjust the brightness by varying that resistance isn't a bad idea.

So, to sum up, the stompswitch operates separately from the stereo input jack.  One provides power to the pedal as a whole, and the other provides power to the LED in particular.  Does that make sense?

[trumpus]

1) Once you plug into a stereo jack, the effect is "on" all the time.  This is why the bypass switch is called "bypass" rather than "off" - because it redirects the audio signal rather than shutting down the effect.

OK, i understand this, now.  So then why do people use a stereo input jack for a passive TB pedal, when the only power going to any part of the pedal is to the LED?  Can i wire it, uch that when there is no plug in the input jac, there is no power going to the LED?  Is it as simple as wiring the groung to the ring of the stereo jack, such that when there is no plug in the jack, the circuit (power to the LED) is not grounded?  If i use a DC jack, do i also need to wire the ground to the ring, rather than the sleeve to achieve this same result?

Also, what exactly does "ring," "sleeve," and "tip," even mean (bear with me, i'm a complete newb!)

Brian

[dpresley58]

http://en.wikipedia.org/wiki/Tip_ring_sleeve

This should help...

[Mark Hammer]

... why do people use a stereo input jack for a passive TB pedal, when the only power going to any part of the pedal is to the LED?  Can i wire it, such that when there is no plug in the input jack, there is no power going to the LED?  Is it as simple as wiring the groung to the ring of the stereo jack, such that when there is no plug in the jack, the circuit (power to the LED) is not grounded?  If i use a DC jack, do i also need to wire the ground to the ring, rather than the sleeve to achieve this same result?

Well, in fact if there is no power going to the board, there is no power available for the LED, right?

The general scheme works like this:

• The "hot" lead going to the V+ connection on the board goes to (comes from, actually) the power jack.
• At the power jack, the "default" connection is to the battery.  When a plug is inserted in the power jack, that default connection is interrupted and power is now drawn from the external supply.
• Even if there is no external power plug inserted, the battery is not completely in circuit ("on") unless a phone plug is inserted into the (stereo) input jack.  Inserting a mono plug into that jack results in the ground end of the battery getting connected to ground so that current can now flow.
• The LED draws its power from the board.  The bypass switch does not affect the power going to the effect circuit, but it does affect whether power from the board finds its way to the LED.
• The stereo jack does not HAVE to be the only way of turning power on and off.  The user is entirely free to wire in a toggle switch or some other switch (e.g., a pot with a switch on the back) to turn the battery off even though a plug is still in the input jack.  Some folks like this as a way of safely leaving things plugged in, though with the number of folks that use pedalboards with shared power supplies going to each pedal, the need for such a "backup circuit" is not that common.

[aron]

Brian,

I understand you are excited but please read the FAQ and look at the pictures please.

When you ask, what is ring, tip, sleeve it makes me think you don't even look at the pictures.

"Power - How do I make the input jack switch the power on and off?

Get a stereo 1/4" jack for the input of your pedal. Connect the tip connector to the input of the effect. Connect the sleeve to the ground of your effect. Connect the 3rd connector (the ring) to the negative of the battery (or the positive if your pedal uses a reversed power supply such as the Tycobrahe Octavia or some Fuzz Faces). When the cord is inserted into the jack, the ring connects to ground completing the circuit."

[trumpus]

Aaron,

Thanks for clearing that up.  I will re-read (yes, i've read your FAQ and the GeoFEX FAQ sme time ago now) the FAQ, so i don't ask anymore stupid questions.

Brian

[aron]

No, those are very good questions you are asking and apparently a lot of others have asked the same ones!!!