03-09-2014, 05:15 PM
Alan - the requirement for those voltage-equalising diodes may not be necessary with modern rectifier diodes, but from personal experience, they are necessary with the 1N400x series. But even with diodes where those resistors may not be required, a few low-power resistors are cheap - especially compared to a burnt-out H.V. winding of the power transformer, should a bi-phase rectifier scheme fail with all diodes short-circuited ! Yes - I've been there! 
Al.
Al.
