Can/should a power supply with +12V and -12V outputs be used to produce 24VDC?
Here is a supply (QP-100-3B) I am looking at for a hobby project and I need 3.3, 5, 12 and 24VDC.
link fixed
http://www.meanwell.com/mw_search/QP-100/QP-100-SPEC.PDF
No you can not with that supply. All GND's are connected so you just have -12V and 12V.
If it was a separate supply it was possible. If you have a separate -12V 12V supply you can connect the -12V to the GND of the first supply and leave the GND of the second disconnected. But with one supply, not possible.
And because you did not specify anything else I can't help you any further.
Btw, link is dead (anti hotlink probably).
What he is saying is that you need a supply with GND and +24V , not a supply with GND, +12 (to GND), and -12 (to GND).
You can , however , use two 2-prong AC/DC 12V adaptors and connect the (+) positive of one to the negatative of the other , tape that up so that it cannot make contact with anything (or solder it and use heatshrink) and use the two other ends of both supplies which would give you 24V. This can only
only be done with floating supplies (the type that do NOT have a 3rd prong for Earth GND)
Most larger supplies, though not all, HAVE and earth ground terminal on the screw terminal strip.
Whether or not this type can be used depends on whether the Neutral and Line terminals are isolated from the earth ground terminal. Since this type requires a user suppied line cord, a 2-prong cord could be used and the earth ground left disconnected and positive output of one of these supplies connected to the negative output of the other supply in the same fashion. the two outputs (one "+" ) and (one "-") that are not connected to each other would be the two outputs of a 24V supply with the "-" being the GND. This method of connecting two 12V supplies in SERIES, is obviously not the preferred method and requires electrical or electronics skill to avoid a disaster.
You should NOT do this if you are not electrically inclined and do not completely understand the above. You should find a 24V supply. If you were to attempt this with supplies that have Neutral shorted to earth GND you would trip the circuit breaker.
And FYI, if you are going to discuss power suppies on the forum you need to specify the current rating.
Sorry here is a better link...
raschemmel:
And FYI, if you are going to discuss power suppies on the forum you need to specify the current rating.
Why is the current rating important in relation to my question?
septillion:
And because you did not specify anything else I can't help you any further.
You answered the question so no further help is needed.