I bought the linked a/c→d/c PSU 2nd hand. I did not look at the connector (assumed it was barrel) and just focused on power attributes. Then when I got home I noticed it has 4-pins. Luckily there is a diagram on the sticker, which says:
P1,2=+12v P3,4=gnd
So I imagine P1 and P3 could supply 12v to a 12v device, and same for P2 with P4. Correct? I’m a bit surprised pins 3 and 4 are labeled ground and not negative. It’s a round connector, so I wonder if the outer ring is actually made to be negative. The a/c input is 3 pin (i.e. grounded).
I wonder if I am misunderstanding because I don’t get the point in 4 pins in this context. If the original appliance (LCD or whatever it is) needs two 12V supplies, why wouldn’t it simply be a 2 conductor barrel considering the appliance could internally wire two circuits in parallel?
I bought it to drive a device that needs a barrel. I’m not really happy to cut the connector off b/c I might one day end up with a 4-pin device, but I guess it’s not worthwhile to try to track down a 4-pin female tip locally to rig it up non-destructively.
To be clear, the appliance needs 12v 5A, which is how the 4-pin PSU is labeled. I hope it’s not a case where each of the 14v pins have 2.5A max.
This image below is not the PSU I have, just something I dug up, but it suggests a purpose for 4-pin connectors that I can understand, as there are two different voltages supplied:
Although I don’t understand what it means to have prohibited signs on two of the pins. Is that a suggestion that they be used as negatives, despite being called “gnd”?
In this photo it’s simply saying if you need 12v on the right dont use this power supply because it’ll go into the 5v side of whatever you’re powering. Keep in mind these are just standard din connectors. They’re not tied to a standard pinout and are used for all kinds of things
WRT your op it’s about current capacity of the connector. If I have a device that needs 12v at 8 amps but each pin is rated for max 5a I can deliver 12v at 4-5 amps through two pins and tie them both to the power rail on the pcb to get a full 8a capacity