Guest Enforcer83 Posted November 12, 2010 Report Share Posted November 12, 2010 Hey everyone,I have an Auxillary transformer that I am using to generate a +5V@1A, +12V1@1A, +12V2@1A, and -5V@500mA. This transformer has a dual secondary from which the negative rail is generated.So my question is this, using linear regulators only, is there a way to balance the load on the two secondaries?Currently I am using LM1085 for my positive voltage regulators and an LM2990 for my negative regulator.Enforcer Quote Link to comment Share on other sites More sharing options...
Hero999 Posted November 12, 2010 Report Share Posted November 12, 2010 Why do you need to balance the load on the secondaries?Unless it's a polyphase transformer, the load on the primary will be the same, regardless of whether the secondaries are balanced or not. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted November 17, 2010 Report Share Posted November 17, 2010 A single transformer with many different secondaries could cause voltage problems. I think the power supply would need to be designed around it. It may be that additional secondary loading could be beneficial if it delivers the desired voltage and makes the design easier. Quote Link to comment Share on other sites More sharing options...
Guest Enforcer83 Posted November 18, 2010 Report Share Posted November 18, 2010 The reason is I want to be able to utilize the full capabilities (current) of both secondaries. If I had to increase current draw on one of the positive voltage rails at some point, or add a voltage rail, I would like to be able to use the side that currently has a negative regulator connected to it so I don't overload one side (which won't be anytime soon but it is something to consider.) Attached is the my configuration. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted November 18, 2010 Report Share Posted November 18, 2010 There's no way to do it without using switching regulators.The circuit you've posted has several issues:The filter capacitors are undersized by at lease two orders of a magnitude.No fuses are required on the output because the voltage regulator ICs will limit the current. Only one bridge rectifier is required, not two. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted November 18, 2010 Report Share Posted November 18, 2010 I wouldn't be sure that you can connect the positive rail to the negative rail because the circuit is using bridge rectifiers. A lot of power supplies use rectifier dioides, and the peak inverse voltage rating of the diode can't be exceeded. Quote Link to comment Share on other sites More sharing options...
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