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Rectifier circuit diagram explanation

Discussion in 'General Electronics Discussion' started by boogie, Jul 13, 2013.

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  1. boogie

    boogie

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    Jul 13, 2013
    Hello everyone! Could you please explain me, how this rectifier actually works? Thank you in advance.
     

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  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    OK I'll explain it generally. For more information, google the words that I've marked between '#' symbols.

    AC mains supply voltage enters through the mains socket. L1101 is a #common-mode noise rejection choke# for #electromagnetic compatibility#.

    The mains transformer has a #centre-tapped primary# that accepts 230VAC between the ends, or 115VAC between the bottom end and the centre-tap; relay RY1102 selects which point the mains is connected to; its coil is powered by IC401 and controlled by Q1111 and Q422 (which in turn are controlled by the P-CON signal from the "main PWB" which comes in on CN1101.

    The main PWB probably controls this signal based on the measured rectified voltage; initially the relay will be in its default position and mains will be fed to its #normally closed relay contact#; this connects the AC mains across the ends of the transformer. If the mains is only 115V, the rectified output voltage will be only half of what it should be, and the main PWB will detect this, and will drive P-CON to the #logic high# state to flip the relay to the other state. The rectified voltage will then increase to the expected value.

    The #transformer secondary# is rectified by D1101~4 which are connected as a #diode bridge rectifier# with its positive output on R402. Current through R402 turns on Q402 which provides the #active low signal# LED- to the main PWB, indicating that mains power is present. The switch above Q402 is operated by the AC mains plug, and selects which DC supply source is fed to the VCC connection on CN1101.

    When the mains plug is plugged into the socket on the unit, the #changeover contact# (marked "1") connects to the contact marked "3' and VCC is sourced from the mains, via the transformer and the diode bridge rectifier. Otherwise, VCC is sourced from the battery.

    This VCC rail is also smoothed by C1106. It supplies the other circuitry on the main PWB.
     
    Last edited: Jul 14, 2013
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