Which prongs are for what on this 5.5mm 12v dc socket?

jpanhalt

Joined Jan 18, 2008
11,088
Center is often positive, but not always. One of the other two lugs is probably switched.

If you know the part number, it is easy to look up. If not, use a diode tester/ohmmeter on the other two contacts.

Unfortunately, what you show do not appear to be a mating pair, as both have male threads.
 

Thread Starter

ralroost einsnulldrei

Joined Jun 12, 2019
13
Center is often positive, but not always. One of the other two lugs is probably switched.

If you know the part number, it is easy to look up. If not, use a diode tester/ohmmeter on the other two contacts.

Unfortunately, what you show do not appear to be a mating pair, as both have male threads.
I don't know the part number, what does a switched lug do? I just need it to run on 12v dc - I have the matching parts here, so no worries there :D
 

djsfantasi

Joined Apr 11, 2010
8,257
A switched lug is closed when a plug is not inserted. It opens when a plug is inserted.

It can be used to switch between battery power and external power. The battery connects to the switched lug, while the positive and negative from the jack goes to power the circuit.

Thus, the battery supply’s the supply voltage until the plug is inserted. Then, power comes from an external supply connected to the plug.

The switched lug can be used in other situations. Like a headphone jack, that cuts out internal speakers when a set of headphones are inserted.
 

MaxHeadRoom

Joined Jul 18, 2013
25,010
In the case of the DC power type socket connector, the Neg side is shorted to one of the other tabs, it is disconnected when the plug is inserted.
In the case of a 1/4" phono plug, the 'live' pin is shorted to one of the other tabs.
I have used the mono phono 1/4" type used as a power commutator for a slow revolving table.
Max.
 
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Thread Starter

ralroost einsnulldrei

Joined Jun 12, 2019
13
So as long as I find the prong that is connected/ shorted to a second one, that will be negative? The device I want to supply with power has no internal battery, if I wire the two shorted together it should (technically) work fine?
 

jpanhalt

Joined Jan 18, 2008
11,088
So as long as I find the prong that is connected/ shorted to a second one, that will be negative? The device I want to supply with power has no internal battery, if I wire the two shorted together it should (technically) work fine?
Why should that be the negative lead? Center pin is not always positive. In most circuits, you can switch the negative or the positive. You can design it either way and some very big manufacturers make the center (not switched) lead negative. It is often easier or at least convention to switch positive.

What don't you understand? Please post a schematic of what you want to do.
 

MaxHeadRoom

Joined Jul 18, 2013
25,010
Yes, depends on what and how you are using it, explain the purpose.
You may, or may not, require to switch one lead over the other.
Max.
 

SamR

Joined Mar 19, 2019
4,127
That's why DMMs were invented... That one is a new one on me. First thought it was a coax connector but it's built wrong for that/wrong gender.
 

Thread Starter

ralroost einsnulldrei

Joined Jun 12, 2019
13
Why should that be the negative lead? Center pin is not always positive. In most circuits, you can switch the negative or the positive. You can design it either way and some very big manufacturers make the center (not switched) lead negative. It is often easier or at least convention to switch positive.

What don't you understand? Please post a schematic of what you want to do.
I don't have a schematic at the moment. Basically it is just 12v dc that will power a circuit board. I simply wanted a plug in the cable. I'm just confused because of the three prongs, I guess.
Easiest would be to just plug it into a live cable and test with the multimeter which side is pos?
 

AlbertHall

Joined Jun 4, 2014
11,957
Easiest would be to just plug it into a live cable and test with the multimeter which side is pos?
Yes - that way gives you certainty. Plug in the power unit you are going to use and you will measure voltage between two pins and they are the ones to use - you will also see the actual polarity. Leave the third pin unconnected.
 
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