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Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 9:52 am
by Shimmer
Trying to build my first pedal and it is close, but not working... I think I have two issues.

1. The DC jack I bought from jaycar is metal - but because the pin is negative, then the outside is positive, and it therefore touches the stompbox - that can't be good, right?

2. I couldn't find a metal stereo 6.5mm input so I bought a plastic one. But instead of three tabs (one for input and two for ground) it has six, three on each side. I figured opposing tabs were connected so I could use either side, but I have a feeling that they are only connected when nothing is plugged in... would that be right?

Any help/advice would be appreciated.
Cheers

Re: Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 10:04 am
by moliere
1. Yeah, you don't wanna use a metal jack in that situation.
2. Depends on the jack. got a link/photo? it's probably switchable stereo, so some of the contacts may connect when plugged in, or connect when unplugged. Good to know which way round. If you've got a multimeter, you should be able to sort out what's what.

Re: Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 10:09 am
by Single coil
Go to plastic jack. Metal jack was the final wtf in one of the wee things I built. Went to plastic and voila. Lights.

Re: Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 10:16 am
by Shimmer
Thanks both. Yes I've read a little more and realise that the metal jack is not what I want.
I think I can still use the stereo socket - I see now that they are listed as 'switchable' which as you say means that the pins are connected when unplugged but not when plugged. I'll figure out which side to connect my wires to and hopefully it'll be all good!
(And I definitely need to buy a multi-meter!)

Re: Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 10:45 am
by jeremyb
If you look at any circuit the -ve of the power will connect to the ground of the pedal which will in turn connect to the ground of the input and output and that needs to be grounded to the case to prevent noise :)

It's not really an issue IMHO....

Re: Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 10:49 am
by TmcB
Yes, why Jaycar persists with those absurd DC jacks is beyond me.
Drop me a line if you need a proper one and I'll post it out to you

Re: Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 10:52 am
by Shimmer
TmcB wrote:Yes, why Jaycar persists with those absurd DC jacks is beyond me.
Drop me a line if you need a proper one and I'll post it out to you
Thanks heaps - I am pretty sure globalpc have them so will check that out first.

Re: Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 10:53 am
by Shimmer
jeremyb wrote:If you look at any circuit the -ve of the power will connect to the ground of the pedal which will in turn connect to the ground of the input and output and that needs to be grounded to the case to prevent noise :)

It's not really an issue IMHO....
But the outside of the jack is +ve (the pin is -ve)- so I think that mucks things up.

Re: Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 10:55 am
by jeremyb
Shimmer wrote:
jeremyb wrote:If you look at any circuit the -ve of the power will connect to the ground of the pedal which will in turn connect to the ground of the input and output and that needs to be grounded to the case to prevent noise :)

It's not really an issue IMHO....
But the outside of the jack is +ve (the pin is -ve)- so I think that mucks things up.
Ahhhhh of course, sorry!

Re: Pedal DC jack/inputs questions...

Posted: Mon Oct 09, 2017 6:05 pm
by Snarblinge
Of course outside of pedal land, dc jacks tend to have a positive tip, so the metal ones make a lot of sense. I use them in positive earth fuzz. Because they look so good, but no generally order the tiny non switched lumberg ones. Have let the battery go.

If this bug bites, you really need to place orders with one of the pedal specific spots, or RS/element, basically anywhere but jaycar.

When you pick up a multimeter, get one with a tone for continuity. Any other feature is a bonus, I still use a pretty rubbish Dse one I have had for years.

Re: Pedal DC jack/inputs questions...

Posted: Wed Oct 11, 2017 3:00 pm
by Shimmer
So I replaced the DC jack for a plastic surround one and wired up the input and output lugs correctly. But then I only got sound when bypassed, but no effect.
It turned out my Boss adaptor had died - luckily I found that out before I started de-soldering the circuit board!
So all finished. Now on to the next pedal! :)