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How can I make a AC 220V to DC 48V (3amp) power supply

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Active Member
You'll require,
1) 220V to 48V-0V, 3A Stepdown Transformer
2) Four 1N5400 High Current Rectifier Diodes
3) 2200uF/100V Electrolytic capacitor

Connect the output of transformer to bridge rectifier made out of 1N5400. The capacitor will connect to the two output terminals of the rectifier (Be sure of polarity).

Thats it! The 2 terminals of the capacitor will be your output terminals.


New Member
well that's the simplest solution...
depends what u need it for.....
do u need it stabilized?
i think that the transformer would be quite expensive..... :cry:
u could opt for a switching power suply, but it would be much more costier, so this is the alternative......
also if u need a good filtering u can conect the first 2200uF cap, the a resistor like 0.47(0.33) ohms/5W then another capacitor and u can improve the filtering, considering that u have a high current...
about the rectifiing diodes, i would recommend to buy a bridge, maybe a 5A one, u wiill get much cheaper, and much more easy to mount and handle....butt be careful when u buy it, because there are good qulity, high speed bridges but only work at low voltage, i recommend one at least 150V.....
glad if i helped with anything


New Member
well, quite a tricky problem.....
i dont know any ic regulstors for more than 24 [email protected], but u can find regulators @4amps and use them...
about the voltage i think u can do something llike a symetrical regulator....
use a 24-0-24 volts transformer, 2 bridge regulators, 2 capacitors and 2 regulators, a positive and a negtive one, so at the exit you will have
-24V, 0V, +24V and between the positive and the negative u will have 48 volts, bu t it's tricky....
another way is to use a power transistor such as 2n3055 or mj2955(they hold 15A) and create a regulator....
but the trnsistors above have a low hFE so u will need another transistor to control it and some reference voltage....
but u decide anout the solution u will pick and we'll try something./
A!, i have a lot of schematics but, some hold 3 or 5 amps, but voltage as low as 25 volts, or some schematics for adjustable 0-50v,/ 2 amps and it's quite complicated


New Member
Regulated Power Supplies

Have a look at http://www.electro-tech-online.com/threads/searching.176/ (our own Stabilised Power Supply with Current Limiting project) -- if this looks OK for complexity then it could be adapted to provide 48v at 3A.

Kinjal's suggested transformer and diodes would be the first changes to the published design, along with bigger transistors (maybe a 2N3055?) and heatsink to suit.


Active Member
Or you can design you own regulator using power op-amp like National's LM12 and a bunch of other components. The op-amp is capable of handling more than 5A current 8)


New Member
the suply only handles 2 amps, it uses 2 LM10C ICs(i dont know how available they are, i didnt look for them), and a few BCxxx and BDxxx transistors and a 2N3055 for the regulator...
u also need some power resistors (3W, 1W, 2W and 5W)
the suply has current limiting so u can set the linit to less than 2 amps..
although it only outputs 2 amps it still needs a 3 amp transformer...
if u think is good for u , give me ur email address and i'll send it to u...
i also have the pcb for it.....
so decide and tell me....
anyway, what do u need it for?


New Member
Hi bogdanfirst

Anyway I want to have a look on the schmatic diagram, so please send me through e-mail ([email protected])

I would use this for telecom equipment testing since it using -48V DC for power up that equipment


New Member
i emailed u the schematic, but if u use it for a telephone, why does it need 3 amps?
and i think that a simple capacitor filter could be enough..maube u can also use a coil and another capacitor and u might obtain a very good stabilised source....
but u must use a thick wire for the coil.....
anyway hope the schematic will help u....
good luck and hapy holiays..


New Member
MY School project is to Design a Step-down Transformer, 200V to 50V,200W. EI.

Anyone can help me for my project? thanks...
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