EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: BlueBill on February 16, 2015, 03:10:04 am
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Is there any practical difference between a full wave bridge vs full wave centre tap?
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Yes, a full wave bridge has two diodes losses, a CT circuit only has one.
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Yes, a full wave bridge has two diodes losses, a CT circuit only has one.
So simple, thanks. :)
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More than that; the FWCT incurs sqrt(2) more losses in the transformer, because only half of the secondary winding is being used at any given time, and each winding is only used half the time. Thus, you need twice the wire, but bigger than half the wire size -- because 50% duty cycle means 71% RMS current.
Tim
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Hmm, so to get the most out of a small transformer like the one below would be full bridge not CT?
(http://www.tubecad.com/2012/08/30/162%20Hammond.png)
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Yes. And the two diode drops of a FWB aren't a big hit if it's more than a moderate voltage (over 10 or 20V, say).
And for lower voltages (20V and below, say), you can use schottky diodes, which lessens the blow of a FWB, so it's not terrible down to, say, 5V or so.
And if you have to have still better efficiency than that, line frequency transformers simply aren't what you need anyway. :)
Tim
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Thanks, it's been so long since I worried about DIY power supplies I forgot the basics.
Q: is there a difference between 2x 6.3VAC secondaries wired in series vs 2x 12.6VAC in parallel?
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With the parallel pay attention to phase. Otherwise it's like connecting two batteries in opposite polarity.