need help getting 12V 15amps

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kagan09

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Hi im confused on how to get 12 volts 15 amps from a power plug which is 240 volts 50hZ. Using a transformer i can get the required voltage but how could i get the current that high ?
 
12V at 15A is 180W. A 180W transformer is big and heavy.
If your transformer is small then it will not have a 15A output and might burn out if you use it.
 
Since you want 12V AC at 15A then you need a transformer that is rated at 180W or more.
Power does not grow on trees.
 
Do you want 12 volts AC or 12 volts DC? Just saying 12 Volts @ 15 Amps doesn't say much.

If you want 12 volts DC then Ian has a good suggestion or find a home PC power supply. Most will deliver 15 amps on the 12 volt output. If you want AC then it is another story. So what do you want?

Ron
 
Last edited:
kagan09 said:
what about using a darlington pair. Wouldn't that increase the current ?
Click to expand...
No.
A darlington transistor works with DC, not AC from a transformer.
A darlington transistor cannot make current, but it can reduce current.
 
An AC power supply will provide an output similar to the AC at your wall receptacles in your house.
A DC power supply will provide an output similar to what is produced by the alternator/battery in an automobile.
Pick one of the above.

An unregulated power supply (AC or DC) will not have a constant output voltage if the incoming power fluctuates or the load on your power supply varies a lot. These are cheaper.
A regulated power supply maintains a constant output voltage up to its maximum current limit. For AC, you will use a "constant voltage transformer". Not cheap and pretty big. For DC, you will probably need a "switching regulator", or a cheap AT/ATX computer power supply.
Pick one of the above.
 
Then salvage an ATX computer power supply. That should give you what you want/need.

Ron
 
Good point Ron.. That way you can he can have spare voltages aswell +5 -5 +3 +12 and -12..
 
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using a PC supply...

1> The ones I've seen use the CPU voltage output (+5 or +3.3) for regulation, you have to load it to some minimum current for the supply to be stable (or even start).
2> The advent of low power disk drives has caused the +12 current of PC supplies to be a smaller part of overall wattage. A 12V @ 15A may be found easier in the ISA bus era, used to run 1+ 5.25 full height hard drives.
3> Your regulators aren't going to work well given no margin on input. You may (or not) only need schottky diodes to isolate the loads.
Good Hunting... <<<)))
 
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