Attached is a simplified diagram of my motorcycle's charging circuit. It has a standard 3-phase bridge rectifier circuit--simple enough.

I'm confused about two things: (1) How is the voltage regulator regulating the voltage here as only one phase is connected to the regulator which appears only to have a ground? and (2) How does this regulator function? All the example regulator circuits on the internet are either linear regulators or zener diode reglators. This one seems to involve a thyristor and a diode?

1977 Suzuki GS400X Charging Circuit

  • \$\begingroup\$ No field winding? \$\endgroup\$ – winny Sep 7 '18 at 12:28

This SCR (not Triac) seems to shunt the core with one phase diode and reverse bias the other phase diode to reduce the generator output in order to regulate. The R divider biases the trigger threshold for 14.2V.

Not as mechanical load efficient as 3 SCR's but works.

Lambda used TRIAC bridges in the old days (the '70's) to pre-regulate DC before higher linear stages as a lab. power supplies. That improved efficiency "somewatt" before SMPS came on the scene.

  • 1
    \$\begingroup\$ Just a nitpick: the symbol used in the schematic is that of an SCR, not that of a TRIAC. \$\endgroup\$ – Lorenzo Donati Sep 7 '18 at 14:26

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