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need help with AC to DC circuit Answered

hi all, im a newbie in engineering but had to do a project on a 2.1 speaker. i need to design a circuit for changing a 240Vac to 14.2Vdc, but after weeks of staring at websites, i still have no idea how to start on it.

i found a circuit online, but i had to modify it to let the output be what it is needed.
output -> Power: 50W; Voltage: 14.2V; Current: 3.5amp

http://www.discovercircuits.com/DJ-Circuits/240vac5vdc.htm this is the link for the circuit i want to modify.

can someone help me please ><

3 Replies

user
LasVegas (author)2007-05-09

If you use a 240v:24v (10:1) transformer with the same bridge circuit you could use a LM350, Adjustable Regulator to calibrate it to 14.2v. It would also give you your 3amps.

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user
LasVegas (author)LasVegas2007-05-09

Sorry... Just noticed you need 3.5a. In that case use the LM138 or LM338 for 5 amps output.

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westfw (author)2007-05-08

That's close enough to a standard laptop supply that you should just buy one from a surplus dealer or eBay. Anything over about 1A gets pretty annoying to design and build yourself, especially if you're going all the way from wall current (commercial power supplies are likely to have custom-built transformers, for intstance.)

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