John Curl's Blowtorch preamplifier part II

[Wavebourn]

I prefer power transformers with internal shields between primaries and secondaries.

[john curl]

A supply designed 30 years ago: The JC-80. For comparison.

[Chris Hornbeck]

Are the primaries really in series? Anyway, the interesting parts are never shown in most schematics, the exact "how" of the grounds.

Thanks,
Chris

[john curl]

Often they are, for 120-240 volt operation.

[Chris Hornbeck]

But actually on a common core?

Thanks,
Chris

[john curl]

Chris, it is the SCHEMATIC DRAWING PROGRAM that limits me to showing it this way. It is ALL one transformer.

[john curl]

MY power transformers don't NEED shields! ;-)

[Wavebourn]

Originally Posted by Chris Hornbeck

Are the primaries really in series? Anyway, the interesting parts are never shown in most schematics, the exact "how" of the grounds.

As you may see, on John's picture "Ground" signs are misleading. Minus from diode bridges should never ever go to ground. It must go to first filter caps. However, experienced engineers know that intuitively without paying attention, so such "too schematic drawings" are common.

[Wavebourn]

Originally Posted by john curl

MY power transformers don't NEED shields! ;-)

I see now why you don't believe that power cords don't matter for my amps!

Even sectioned transformers benefit from shields between primaries and secondaries.

[vacuphile]

Originally Posted by john curl

My contribution: I hope that it answers a few questions. It is not the complete CTC Blowtorch power supply, but it is close enough for discussion.

The front end I use for my PS uses much the same lay out. One thing I found really makes a difference is grounding points. One might be tempted to take ground from the diode bridges and then run it straight through to the 317/337 with associated passives. John shows what I measured to really make a difference. Make separate grounding points at the diode bridge and after the 317/337.

vac