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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.
 
If you want 12V AC at 15A then use a 180W or more transformer.
 
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.
 
what about using a darlington pair. Wouldn't that increase the current ?
Transistors only control current, they don't create it.
 
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
 
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what about using a darlington pair. Wouldn't that increase the current ?
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
 
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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