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Review my Power Supply Circuit - Suggestions

Discussion in 'Power Electronics' started by CluQu, Jun 29, 2013.

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  1. CluQu


    May 22, 2013
    I'm using a 21V DC wall adapter to supply me with 5, 9, & 12 volt regulated supply. Attached is the circuit I made. It's designed to switch between whichever voltage I want/require by means of an SPST switch. The LEDs are there for indicating on/off. My concern with this was to have them before the regulators as to not take away any voltage or current from the 78xx. Thoughts and suggestions are highly encouraged and recommended.:cool:

    Attached Files:

  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    The points you show as outputs are ground connections.

    You have no input or output capacitors on your regulators.

    The power LEDs might be better on the outputs of the regulators (minor point).

    Depending on the size of the output capacitors, you may wish to place a reverse biased diode across the input/output of the regulator.

    Is your 21V DC source clean DC, or is it just rectified, or is it perhaps insufficiently filtered? (You need to know).

    The 5V regulator will dissipate a lot of heat if it supplies significant current and may (probably will) need a significant heatsink. The same applies to the other regulators, although to a slightly lesser extent.

    The 5V regulator, if supplying 1W to a load (that's just 200mA) will be called on to dissipate over 4W of heat itself.

    Given a max output voltage of 12V, an input voltage around 16V would be better.
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