Metal DC power jack question

[LucifersTrip]

Stupid question...I rarely use DC jacks but I had this one lying around:


Do they usually have a standard (+) and (-) lug?   In this case, I believe I'd have to use the long lug as ground (I can see it's obviously the casing).

I screwed it into a metal enclosure, and of course, there was continuity  between the long lug and the enclosure.
If I plug my 9v adapter into the jack and measure the lugs with with black dmm lead on the long lug and red on the small, I get -9v.

Does that mean I can't use this for a (-) ground circuit?

Can you get these anywhere for under $3 each? 3 lug ones? I really hate using cheap plastic in anything...

thanx

[Yorick]

I often use these:



They're a bit in between the complete plastic ones and the metal ones, nice and sturdy despite the plastic!

[nexekho]

That's the one on Bitsbox, I'm wondering, if you use centre negative/outer positive does that run +9v through the nut and therefore the case or is it designed for BOSS-style?

[LucifersTrip]

I often use these:



They're a bit in between the complete plastic ones and the metal ones, nice and sturdy despite the plastic!

These are the in-between ones...half metal...looks much more sturdy than the plastic ones:
http://www.ebay.com/itm/4pcs-5-5mm-X-2-1mm-DC-Power-Supply-Metal-Jack-Socket-S-/170686857518?pt=LH_DefaultDomain_0&hash=item27bdbac12e

..but why compromise if the metal ones are useable

regardless, i'm more interested in my questions above.

[slacker]

Does that mean I can't use this for a (-) ground circuit?

You can use them for whatever you like, positive or negative ground. If your  power supply has the standard centre negative (outer positive) plugs then you have to isolate the jack from the metal case. You can do this by drilling the hole in the case slightly bigger than the jack and then mounting the jack on something non conductive like a piece of plastic and then mounting that to the case. The other thing you can do if you're only going to be using this sort of jack is reverse the polarity of the power supply plugs so they are centre positive (outside negative), the only problem with this is you have to remember never to plug it into a "normally" wired effect.

[Perrow]

the only problem with this is you have to remember never to plug it into a "normally" wired effect.

Polarity protection is recommended.

[DC9V]

Plastic jacks are not necessarily cheaply constructed. I use standard plastic DC jacks like the one on my avatar on all my builds and never had a problem. Actually in my Dirty Bird I used a 24mm pot and therefore had to file down the DC jack on one side so it would still fit, and from the amount of effort it took I can say they are very sturdy .

I wouldn't use all-metal DC jacks in a stompbox, even though they look much cooler. The risk of the homemade insulation shifting or getting worn through would make them far less reliable in the long run than those which have built-in plastic insulation. I have one jack just like the one LucifersTrip has, and it ended up on my breadboard's wooden mounting plate; no risk this way.

Anyway I think I'm going to switch to DC jacks that mount from the inside. It's a pain having to desolder the wires every time you want to take the PCB out of the enclosure .

[asatbluesboy]

Anyway I think I'm going to switch to DC jacks that mount from the inside. It's a pain having to desolder the wires every time you want to take the PCB out of the enclosure .

Isn't it? I don't even usually drive the wires through the holes, 'cause I know I will eventually need to take it apart and desoldering them will be a pain...

[iccaros]

I use the all metal jacks, but then all of my wall warts have jacks that your can change the polarity. I use positive tip on everything. If I am doing a positive ground I just mark that one different, for negative tip. .. After seaching for wall warts throught the thrift markets and goodwill, I found most are + tip. so this works well.

Polarity protection is a good ideal even if you are not using metal jacks..
   

[derevaun]

Agreed--positive-tip supplies are vastly more common than negative-tip supplies, at least in my locality. I don't have any Boss pedals or Boss-style AC adapters anyway. In the situation of needing to borrow a power supply at a show, I have a few power plugs wired to 9v battery clips, which are useful for sorting out hum issues. I just find it a lot more convenient to standardize on positive tip, which is already quite standard.

[Processaurus]

Check out our moderator's solution to using metal jacks with the boss tip negative power:

http://www.thetonegod.com/images/nerfuzz/nerfuzz_back_1.jpg

Pretty cool!

[deadastronaut]

I often use these:



They're a bit in between the complete plastic ones and the metal ones, nice and sturdy despite the plastic!

yep i use those...8mm hole..not  a massive 12mm .... much smaller, bit more room...i don't use batteries ever...

[harmonic]

I often use these:



They're a bit in between the complete plastic ones and the metal ones, nice and sturdy despite the plastic!

yep i use those...8mm hole..not  a massive 12mm .... much smaller, bit more room...i don't use batteries ever...

You guys have a link for those? They look cool, and 8mm hole sounds great!

[nexekho]

http://www.bitsbox.co.uk/connects.html#power

[LucifersTrip]

I use the all metal jacks, but then all of my wall warts have jacks that your can change the polarity.

can you please send a link to one of those...

I use positive tip on everything. If I am doing a positive ground I just mark that one different, for negative tip. .. After seaching for wall warts throught the thrift markets and goodwill, I found most are + tip. so this works well.

funny that you mention that...I was just measuring the last couple 9v wall warts I picked up at thrift shops and they both measured ~ 13.7 to 13.9 v. Is this a weird coincidence or are they both fried?

thanx alot

[amptramp]

funny that you mention that...I was just measuring the last couple 9v wall warts I picked up at thrift shops and they both measured ~ 13.7 to 13.9 v. Is this a weird coincidence or are they both fried?

thanx alot

The voltage rating for these wall warts are for the rated load.  The load discharges the filter capacitor between alternation peaks.  The open circuit voltage you are seeing is what you would expect for an unregulated pedal.

[iccaros]

I use the all metal jacks, but then all of my wall warts have jacks that your can change the polarity.

can you please send a link to one of those...

I use positive tip on everything. If I am doing a positive ground I just mark that one different, for negative tip. .. After seaching for wall warts throught the thrift markets and goodwill, I found most are + tip. so this works well.

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

[white paw]

i stupidly bought a similar jack for a build, to isolate it, just run some wire out of the pedal and leave it flopping around. aint pretty but it works! i used ducttape and electrical tape to try to reinforce the whole thing too so i didnt accidentally break a solder joint or rip the guts of the pedal apart 

[Paul Marossy]

I used those metal jacks in the past, RadioShack sold them. I would wrap it with a little electrical tape and use a pair of O-rings to isolate it from the enclosure so there wouldn't be a dead short on the power supply. Never had a problem with any of those builds. But using the plastic jacks is just a whole lot easier, not to mention more than 50% cheaper.

[LucifersTrip]

i stupidly bought a similar jack for a build, to isolate it, just run some wire out of the pedal and leave it flopping around. aint pretty but it works! i used ducttape and electrical tape to try to reinforce the whole thing too so i didnt accidentally break a solder joint or rip the guts of the pedal apart  

please tell me you're joking....