brady wrote:Hi Tony. A quick question re stacked diodes.
I have around 800vac on the 2ndary, unloaded, so I stack 2 1000PIV diodes for each leg of the bridge. I kept busting both the diodes and the fuse to the mains transformer. Read other forums, and I shunted each diode with 1M. Problem disappeared.
But I do not understand. Why a shunt R? I imagined that such voltage divider works only for series C.
TIA for whatever free lessons you can give ....
800volts rms is about 2400volts peak to peak, this peak voltage is what the diodes see when in cut-off, so 3 1kv diodes in series would have been better, shunting it with 1meg resistors each ensures equal voltages are seen by each diode when not conducting or during reverse cycle of the input voltage...
