Thread: "Y" Power connectors

I once connected two AT PSU's 12 volt lines together, for more Amps. Turned the first one on and it started to spin the second PSU's fan. I never did turn the second PSU on. I was too scaried I must blow something up. I ending up using a better PSU (more Amps).

That being said, nothing should blow up. As long as one or the other PSU is off. I don't know about possible long term damage.

understand now, I am the furthest thing from a EE there is.. I think it would be ok if you used diodes on the hot lines.

That would be a decent about of diodes. You would have to split most of the lines on the "Y" going to the DC-DC PSU. This would block the power from being feed into the DC-DC PSU. Don't forget diodes will drop the voltage abit. This method would be the best way to assure that no power is getting feed into the DC-DC PSU.

I'm not an EE either.

Have you tried to power you DC-DC with the 12 volts from your AC/DC PSU? ATX PSUs require you to short two pins to turn the supply on. The green (Pin 14) is designated as the power on line, while the black (Pin 13) is just a ground line.

Have you tried to power you DC-DC with the 12 volts from your AC/DC PSU?

I did think of that, but thought is would not be a good idea.

The other option would be to build/find a switch to break the lines to the DCDC when ACDC was connected?

I have a printer and a serial switch box, that would do the job,
but I'm not sure if the switch would handle the load.

Originally posted by GRUNT

Now that I have the Sproggy inside the case I would like to build the "Y" power connectors.

This is something I have wanted to do for months, just not had the time.

Thanks for your help.

I don't understand why people don't just use a AC to DC 12 volt converter. This Y issue has come up so many times. Just take the 12 volts from your AC-DC power supply that you want to spend so much time building a Y connector for and just connect the 12 volts from one of the hard drive connectors to the 12 volt input of your DC-DC power supply. Why is this so hard? It seems a lot easier than spending 30 dollars on diodes. What could have possibly made you think this isn't a good idea? It is Ten times better than a Y connector. Will all the parts on the motherboard that are 3.3 volt run at 2.8V? Sounds like a BAD idea to me.


-Jeff

just connect the 12 volts from one of the hard drive connectors to the 12 volt input of your DC-DC power supply.

Did not know that it would be safe to do that.
I know you have much more experience about this subject than I do.
So if you think it's OK.
For me this would be the best and easiest option.

Thanks for clearing this.

Originally posted by GRUNT
just connect the 12 volts from one of the hard drive connectors to the 12 volt input of your DC-DC power supply.

Did not know that it would be safe to do that.
I know you have much more experience about this subject than I do.
So if you think it's OK.
For me this would be the best and easiest option.

Thanks for clearing this.

You might need to put a load on the +5 volts. If you have some old hard drives, you might have to plug them in just so the min load requirement is met on the 5 volts..

Other than that, it is cheep 12 volts at 8 amps?

When I was planning the current rev of my car pc that had me looking into this a few months ago, I wanted both in the same case, which would have allowed me to use either power supply in either setting without any external boxes. As in this thread, some said it would be ok to just hook both up, some said diodes, some said switches. Im still just running a AC-DC psu off an inverter, so I never looked into the matter further, but if someone had some money and old hardware to spare, the most conclusive answer could be generated by just hooking them both (dc-dc and ac-dc) up and seeing what happens.