How can I add an LED to a DPDT switch (change to 3pdt I assume)??

[claytushaywood]

I'm really bad with switches and LED's for some reason.  I understand them but I'm not exactly sure how to change a DPDT switch on any pedal to a 3pdt (I assume that's nescessary) with an LED indicator.

Does anyone know of a link or have some info that could help me understand this?
I'd really appreciate it!

[jkokura]

There probably isn't one single location to get better information than Beavis Audio's Tech pages.

http://www.beavisaudio.com/techpages/Switches/

Jacob

[juansolo]

http://www.geofex.com/article_folders/millenium/millen.htm

[9Lives]

There probably isn't one single location to get better information than Beavis Audio's Tech pages.


+1 I've built a buttload of pedals at this point. And I try to use dpdt if possible just bc I like them better, but when I use 3pdt I still catch myself looking at beavis audio. The diagrams very clear. Don't get confused by the multiple ground points. Technically you may only need one, but I think most of use ground everything to the enclosure.

[claytushaywood]

i mean I understand how switches work and how to make an LED go On and OFF (well that part kinda).  Sooo... let's say (for example) I have a DPDT ON/ON switch with a capacitor going from LUG 1 to LUG 4 on one side and the other side has one going from lug 3 to lug 6 with lugs 2 and 5 going to the board or whatever.  Say I want the LED to come on when the first cap is in the circuit (between LUG 1 and LUG 4).  Could I just connect the ground to LUG 4 and the LED negative lead to LUG 3 (with the postive end connected to the CLR and then to 9v+)

or would I need a 3pdt and throw the LED stuff on it's own lugs?  BEcause that would take one of the caps to ground now that I think about it...  You know how you can put 2 capacitors on an SPDT 2 position switch?  If I took a DPDT and hooked up these 2 (for example) capacitors on one colum of lugs liike it was a 3 lug SPDT switch.  Could I then use the other column for the LED... Iss that the gist of it- you basically have to add another column of rows to your switch to add an LED?

Here's the DPDT numbering

1   l    l   4
2   l    l   5
3   l    l   6

[skullservant]

Ran into the same issue over the weekend when I was trying to wire up a blend control that could come and go out of the circuit. I just ended up going with a 3DPT cause I knew it would work correctly. I know it's not ideal, but it works

[jkokura]

Let me try and make this as clear as I can. I wish I could show you in person because that's easier.

There are two ways to do this. You need at least 2 poles, but you can also do it with 3 poles.

As you mentioned, to just switch between two caps, you'd put one cap between 1 and 4, and the other cap between 3 and 6, and lugs 2 and 5 would connect to the spots on the board. Now, if you wanted to add to that setup, and change nothing but including an LED, you would need to add another pole. This last pole, numbered 7, 8, 9 from top to bottom, would have a ground connection on 8, and you can either have one LED for one side or an LED for both sides. Whichever cap you want to have the LED light up for, that's the side you connect the negative end of the LED.

If you want to just use a 2PDT switch, you would have to adjust the way you do the caps. You would leave one pole to the LED, and it would be the same as above, with the GND on lug 5, and the LED on either 4 or 6 depending on which cap you want to light up. But the caps would not attach to two lugs. Instead, you would go from one pad on the PCB to the middle lug (2), then each cap would attach one leg to the switch (lugs 1 and 3, one for each cap), then the other lead of the caps would BOTH attach to the other pad on the PCB. In effect, it's the same thing as above, just using a DPDT switch instead of a 3PDT switch.

Jacob

[LaceSensor]

just to add to this, the other side of the DPDT could be hooked up with a bicolor LED which could be cool.

I added a breif cartoon to illustrate this, and the advice above

dual colour LEDs are on Tayda right now for about $0.30

Nb I forgot the CLR on the first 2 cartoons, youll need one obviously.
You can use the two seperate LEDs with the DPDT switch too, should be obvious from the cartoons.

[night-B]

http://www.diystompboxes.com/analogalchemy/sch/ledtrick.html

Julien

[claytushaywood]

so basically on a free column of a switch labeled

1
2
3

I would have to connect a ground (any ground tap?) to lug 2... and the negative lead of the LED to either 1 or 3 depending on which side of the switch I want lit up... or to both using a bicolor or two LED's... and can I just tap 9v anywhere to go to the CLR then to the positive leg of the LED? 

If i just put another wire coming off the DC jack (as there would already be two- one going to the board and one going to the main on/off indicator) will that be fine?

[jkokura]

Yes, that's how it would work.

Yes, tap the 9V with a CLR to the LED. The CLR can come after the LED too.

Yes, another wire from the DC jack will do the job.

Jacob

[LaceSensor]

Hmmm