Electronics > Beginners
Is it bad practice to leave a transformer secondary floating?
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Chris Wilson:
Someone told me that it's bad practice to leave one half of a centre tapped secondary  (6-0-6 V) floating. The transformer is a small PCB mount 0.5 Amp output 240 V mains one. I full wave bridge rectified one 6V winding and left the other one floating. Is this bad? Thanks. I am sure I have seen lots of transformers in things with unconnected secondary taps, so have doubts over this advice...
Ian.M:
Its not bad practice provided the load on the half-winding is well within its ratings.  However if you are pushing its limits, it would be better to use two diodes from opposite ends with the center tap to provide full wave rectified DC with the I2R losses distributed over the whole winding and half the diode losses.
schmitt trigger:
If you use a full wave center tapped rectifier configuration instead of a bridge, you would save a couple of diodes....a few pennies.
Perhaps most importantly you would save one diode drop, which in low voltage supplies will provide extra headroom to the regulator.

Otherwise, just insulate the loose wire.
Chris Wilson:
OK, understood and many thanks. I suppose I could parallel the two windings with due regard to phase and keep my single device FWB rectifier, so the current capability was doubled? Not that i am drawing more than 100mA from the bridge anyway.
cvanc:

--- Quote from: Chris Wilson on July 04, 2019, 02:14:49 pm ---I suppose I could parallel the two windings with due regard to phase

--- End quote ---

Wait, in the first msg you said it was a single center-tapped secondary.  Here you say it's 2 independent secondaries... please clarify?
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