Using a non-bridge (2 diode) full wave rectifier in bias supply. - diyAudio
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Old 26th February 2012, 06:33 PM   #1
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Default Using a non-bridge (2 diode) full wave rectifier in bias supply.

Hi folks!

Is there any reason why I shouldn't use a 2 diode full wave rectifier for an unregulated bias supply? I never see schematics (new or old) in this configuration, so there has to be a reason NOT to do it. No? I've got an old 50-0-50 trannie that puts out about 100 mA...I figure it would give me 60V after smoothing.

Thank you,

John.
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Old 26th February 2012, 06:41 PM   #2
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There is little reason to use full wave rectification in a bias supply since there is so little current being drawn from the supply.
Technically, there is no reason why you can't use such a supply.
Build away.
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Old 26th February 2012, 06:44 PM   #3
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Mainly becasue for this conviguration you either need to halve the supply or have a center tapped winding, therefore this is very inefficient. As the bias supply doesnt need to supply much current not alot of smothing is needed. A bridge rectifier would be much better. You said 50-0-50, that could be 100 volts. 100ma is alot for a bias tap. anyway 100*.1 = 10VA 50*.1 = 5VA
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Old 26th February 2012, 07:08 PM   #4
DF96 is offline DF96  England
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You could use the transformer with a bridge to provide a 60-70V negative bias supply, and a 120-140V negative tail supply for an LTP.

The reason you are unlikely to see this is that it is expensive to have a special transformer for this purpose. Since you have it you might as well use it. Alternatively, use it to power a lowish voltage preamp.
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Old 26th February 2012, 08:18 PM   #5
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Thanks for the quick replies guys! Maybe I'll use a bridge anyway, then use a voltage divider or some type of regulation to bring down the voltage.
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