Best method to drop voltage 10V/7.5A for power supply 5V/7.5A

Discussion in 'The Projects Forum' started by witssq, May 5, 2010.

  1. witssq

    Thread Starter Active Member

    Mar 29, 2009
    There is a transformer rated secondary 18V@10A to make power supply with 5V/7.5A regulated voltage.

    What is the best method to drop voltage to 8V@7.5A for bridge rectifier
    because of too much heat for regulator?

    Please advise me an solution for this problem.

    Thanking you in advance

    SunSung Hwang
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Whatever you do using a linear approach you've got to dissipate 60W of heat somewhere (for example in a high wattage series resistor) - so why not just source a transformer with a more appropriate secondary voltage? Otherwise you go for the switch mode approach which is probably not your preferred option.
  3. witssq

    Thread Starter Active Member

    Mar 29, 2009

    I would like to make, with one dual transformer, +15/-15V for analog circuit, +5V for digital circuit.
    The standard dual transformer seems to have ratings as same secondary ratinig. So I could not find +18V, +5V rating.
    To do so, I use 2 transformer with +18V rand and +5V rating.

    I have one more question. I have receive the following answer from transformer manufacturer.

    Qusetion to maker is "Can the A41-130-36 is used individual and independent dual"
    The two secondary winding of the A41-130-36 could be used individually as two independent 18V winding however please be aware that the winding are not sufficiently isolated. The only insulation between them is the enamel of the magnet wire and thus the dielectric strength from one to the other is a mere 100V.

    Please advice me the meaning of isolation, and to use for individual how I design circuit for very stable and low ripple psu with +/-15V(analog) and +5V(digital).

    Best regards,
    SunSung Hwang
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