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mbeards 10th August 2012 03:51 AM

Transformer center tap question
Hi everyone,

So I am installing a VU meter on my amplifier the I got of ebay.

The vendor also sells the power transformer to drive the board. The board requires 24V and the transformer is 12-0-12V So i will use the two 12V taps to power the board. Now normally I know that with a full bridge rectifier, you don't use the center tap on the transformer. It would short the secondary since the full bridge is usually referenced to ground.

However with the VU driver board's bridge is not referenced to ground anywhere since the board is all self contained. It is rectifying the 24V AC from the transformer aka the two 12V taps with the low side of the rectifier ungrounded.

In this instance, should the center tap be used to reference that circuit to ground somewhere too keep it from floating?

Sorry for the poor explanation,


Junm 10th August 2012 06:00 AM

using th 12vac in series is 24 volts going to the board...don't use the center tap since one terminal will refer to ground....not unless there's a need for + and - rails...

TonyTecson 10th August 2012 07:01 AM

check to see what your vu meter board require i mean B+...

Tom Bavis 10th August 2012 05:16 PM

Let the circuit float - it will be grounded when it's connected to a circuit for measurement. Ground any other point and it may introduce a ground loop.

tomchr 10th August 2012 07:00 PM

Leave the center tap floating. Cut or tape/heatshrink the wire to ensure it doesn't accidentally touch the chassis or any component of the amp.


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