Electronics > Beginners
Can power supplies be linked together like batteries for higher voltages/amps?
Beamin:
So while I don't have a 60V power supply I do have 5 12 volt ones of the ATX computer flavor. A sixty volt few amp power supply = $$$ but ATX power supplies are almost free. Buy an old Compaq at the good will for 10$ throw away the computer and keep the power supply.
Can you put these in parallel or series to get higher voltages or current? I would imagine they would have to be the exact same rating if not the exact same brand and model so that the weakest one is not getting over loaded. But if not why aren't power supplies able to be put in a circuit for greater V or I like batteries? I'm talking DC where you don't have to worry about things being in/out of phase. What would be nice is if I had above 30 volts so I could run tubes. I'm a big fan of the auto shut off the ATX have incase you short something, which has saved my ass many times. I think when I tried this as a kid one power supply kept going into protection mode, but who knows, my goal as a kid was more for the destruction and overload of devices rather then the creation and smooth running within spec of the unit, like now. Gun powder and flash powder was a tool I employed often. When your only tool is a hammer all your problems look like CRT screens.
Brumby:
Can you put power supplies in series for higher voltages?
* YES - but ONLY if they are floating with respect to each other.
Can you put power supplies in parallel for higher current ?
* A qualified yes. There are issues with balancing the load drawn from each supply. For example, say you have two 12V supplies than can deliver 10 A each and you want to connect them in parallel to drive a 12V 20A circuit. With them being two independent supplies with the possibility of slightly different characteristics, such as voltage output, you might have one that will try to deliver 15A until it sags enough that the other supply will kick in the extra 5A. Needless to say the first supply isn't going to be able to do that.
Brumby:
For series connection, the maximum current available will be the maximum current capacity of the weakest supply. So if you have 3 supplies of 5V 25A, 12V 10A and 12V 2A, you can have a supply of 29V at a maximum of 2A.
Brumby:
For parallel connection, you will certainly want the output voltages to be as well matched as possible - but even so, there will still be small variations.
One option that has been used is to have low value power resistors in series with each power supply before being connected to a common point. The calculation of the value of these resistors will depend on the situation.
Mr. Scram:
Many two channel power supplies offer this feature. An example would be having either two channels of 0-30V of 3A each, or one of 0-30V and 6A, or one of 60V and 3A.
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