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15 Vdc power adapter

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Quick question it's hard to find one that's 2 Amps unless it's like a laptop power supply, but given most are the single wire plug type if you cut the end off can you use the ground wire which most likely will be wrapped around the positive wire? Most I noticed don't come wrapped in wire so I have concerns about shorts
 
I don't understand your question. Are you are talking about cutting off the plug on the output (low voltage) side? If so, the output wire is usually only two conductors; sometimes a flat "zip" cord, sometimes a coaxial (center conductor and shield) cable.

It doesn't matter which type of wire comes out. You will have to experimentally determine which of the the two conductors is positive and which is negative; there seems to be no consistency. The wire with the white tracer might be either neg or pos. The center conductor might be pos or neg.

In all the wall-wart transformers I have looked at, neither of the output wires is common to the transformer input, even if the line side has a three prong line cord. That is not the case if the brick is actually a switch-mode electronic power supply (not a heavy transformer). You can usually tell just by the weight if you have a real transformer or an SMPS.
 
Yeah, well what I did is ending up getting a 18.5V 3.5A power supply I'm pretty sure the plug wont fit the radio shack M-plug so I can cut that off and put on the plug I got from the store.

I know most like you said are two conductors or just coaxial, more so coaxial.
 
A 18.5V 3.5A power pack is almost certainly a SMPS. Check with an Ohmmeter to see if either of the output wires has DC continuity to the middle prong of the line cord (if it has a third prong). If only two prongs on the line cord, check that neither of the output wires has continuity to the line side...
 
Center pin no continuity to the line side of the plug same for the ring terminal.

output voltage is 18.6V
 
Then it provides "floating" power. Now the only problem you are likely to have is the RFI generated by SMPS.
 
well the RFI is not much of a problem, now it's time to cut the end off..

it's going to be in a closet so it's pretty far from anything that would be effected by RFI.
 
Wow the whole reason why I ordered this was I needed a higher supply current but I just thought about it.. If I 3V more input for the LM317 then my old adapter while it was 17V unloaded when loaded with pretty much any load it would drop down to 12V no wonder the charge rate was a bit slow..

It's connected now and working pretty good, I will be adding a temp controlled fan for the heatsink since it's at 62C in free air now in the box I expect higher.. It has to be temp controlled since it's a 40mm fan that moves 24 CFM so it's almost 60 dbA
 
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