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Jim,
You cannot pass a ground through a bridge. The only way you could
grounded one end of the bridge is if you had an isolation transformer
before the Variac. Both ends of the post-bridge circuit have to be
separate from ground if you have no isolation transformer.
I'm not sure how you would be connecting two bridges together.
The AC inputs of the bridges should be the low, or neutral end of the
Variac, and the wiper. However, both the + and - outputs of the bridge
will still be "Hot" with respect to the 110 volt power. You cannot
ground either one of them.
..........Variac
--(Hot)------)
.............)
.............)
.............)<--(Wiper)--------> To bridge
.............)
.............)
--(Neutral)--|---(Neutral)------> To bridge
I re-did the ASCII art 'cause it got mangled, at least when it displays
on my system. Ignore the dots.
Dave
On 8/28/2014 10:58 PM, jj@xxxxxxxxxxxxx wrote:
I again checked the strings on each bridge and they are all correct as
per the schematic. For the record the diodes are"10A 1000V MIC 10A10
High voltage diodes". Both bridges have the same problem. Could it be
the diodes?
On 8/28/2014 8:31 PM, David Speck wrote:
Jim,
Your schematic should look something like the following, with a whole
lot more diodes:
..............(AC Input).............
..................|..................
|--|>|--|>|--|>|--|--|>|--|>|--|>|--|
|...................................|
|.(-)...............................|.(+)
|...................................|
|--|>|--|>|--|>|--|--|>|--|>|--|>|--|
|.................|.................|
(Negative).....(AC Input)......(Positive)
(output)........................(Output)
I'd guess you have one leg of the bridge turned around.
Dave