SPST > DPDT & LED question...

[bobbletrox]

http://www.generalguitargadgets.com/v2/diagrams/ftmpl.gif

JD's replaced the octave SPST toggle on his Tone Machine with a 3PDT footswitch and thrown in some indicator LEDs to boot.  Now, I wanna try out his uber-practical idea using a DPDT instead of the SPST, and I've been staring at his wiring layout for a while trying to work out...but it's hurting my brain!   :shock:

I'm not sure if this is right, but is this the way the SPST in JD's wiring diagram should be rewired for a DPDT?

Code Select Expand


         _____
         |O|O|
 GREEN-> |O|O|
 BROWN-> |O|O|
         -----


I'm even more confused about the LEDs.  I've looked at the inside pic of his Tone Machine;
http://www.generalguitargadgets.com/v2/pics/ftm_inside.jpg

...and it looks like each LED is wired to the + DC connector with a Y joint (look near the center pin of the middle pot), but I can't work out how I'd apply it to my project because I'm not using 3PDTs.  How would I go about wiring LEDs for my two DPDTs?

Any help would be appriciated!

[mattv]

Your diagram for the octave switch is correct. Now connect the appropriate lead of the LED to +9V through a 4K7 (or so) resistor, connect the other lead to the middle lug of the switch and connect the lug of the switch adjacent to the brown wire (in your diagram) to ground.

Now, when the switch is closed, the LED will light up. If you want it the other way around, connect ground to the opposite lug.

HTH!

[Mike Burgundy]

4k7 might be a bit high for some LEDs: at 9V supply this will allow less than 2mA. Most LEDs have a nominal working current of 20mA.
If the LED doesn't light, or is too dull try a lower value resistor (1k, or even 470Ohm, but don't go below that. I usually stick in a 1k for high brightness LEDs)

[smoguzbenjamin]

Yah mike, but battery life is also a big issue... I've found that a 3mm LED will burn fine at 2mA with good brightness. For a 5mm LED I wasn't pleased with the brightness untill about 4mA, but 20mA? Once you get over 10mA the brightness doesn't get much better and unless you intend to ALWAYS use a high-current PS I would try to keep current consumption down.

just my 2 cents

[bobbletrox]

Now connect the appropriate lead of the LED to +9V through a 4K7 (or so) resistor, connect the other lead to the middle lug of the switch and connect the lug of the switch adjacent to the brown wire (in your diagram) to ground.

Great!  Thanks.   :wink:

How would I do that with the Bypass DPDT switch?  I'm beginning to realise how handy a 3PDT would be right about now.

[Mike Burgundy]

Once you get over 10mA the brightness doesn't get much better and unless you intend to ALWAYS use a high-current PS I would try to keep current consumption down.

Agreed. 2mA won't light most of my LEDs, hence the remark. 20mA is their full-on rating, which is too much for all but the laziest LEDs. I'm not exactly sure how bright they are, but they were listed as ultra-brightness - I use 1k for blues, 1k6 for whites and 2k4 or something for reds. (range from  4 to 9mA).
I also have some *really* bright SMD LEDs (120 degree angle but they still hurt your eyes at 3 yards) that simply won't do anything under 12mA. Weird

[bobbletrox]

So is there no way to wire an LED up for the bypass DPDT on the Foxx Tone Machine?

It's really buggin' me out  :cry: