Inverting GC variant

[Russ White]

Please excuse my simple question, but I am still new. I see you use two sybols on the schematic for ground, one which is labeled "gnd" and the other "0V". Looking at the schematic it seems the one labeled "0V" are signal ground and that "gnd" is power ground. Please help me understand if they should be trtead differently, or if I should look at them as all terminating at a star ground point.

Thank You,

Russ

[mauropenasa]

It's correct. 0V = signal ground, gnd= power ground. Is important that the 2 signals take an oath different run, and they crosses only in the star center of Large El. Cap + Diode bridge.

Mauro

[Russ White]

Wow, you answered my next question before I could even ask it! I was going to ask about the diode bridge. Are the diode part numbers critical? I have some 100V 3A fast recovery diodes. Will they be OK?

[edit] I re-read your previous post. It seems you meant the diode bridge at the power supply. I was referring to the two diodes D1 and D2 near C4.

[mauropenasa]

The matter of the PSW is a lot of controversial in this forum, and I hope to not creating problems exposing my point of view. In my circuits I uses from a great deal of time a integrated diode bridge , with tides >10A and >100Vac, and 2 El. Cap. from 10.000µF. in the circuit " My amply " I have make a diode bridge DIL from 5A suns without never corresponding any breakdown, but it be worthwhile always abound with the current margin.
Generally, all the variations of PSW that have seen in this forum even is proper to my ideas. I suggestion to use un integrated Diode bridge, much near to the El cap, and inserts always a MKT capacitor from about 100nF among the 2 points of Vac1 and Vac2 ( as from MY ampli ") and weaves the wires of the transformer. The seas to discrete diodes is a generators of high frequency spike, and the nets of capacitor about doesn't always succeed to resolve the problems ( perhaps for this the snubber net are do profits...) I prefer eliminate the problem to the base. Other fundamental thing is that the PSW is more possible near to LM3886, because the connection wire create a lot of problems.

Mauro

[Ed LaFontaine]

Thank you for your posts, maupenas. You show us a strong foundation in fundamentals and an aversion to fashion.

[Russ White]

Mauro, thanks for all the good info.

I am still not clear on the purpose of D1 and D2, could you please enlighten this beginner. Also could you give me minimum ratings for those two parts.

Thanks,
Russ

[mauropenasa]

I have forgotten me... D1 and D2 serve only to protect U1b +IN from voltage transients. Goes well all the signal diodes of 100mA >10V, have provided that a Vd 0,5V. The circuit even works without, but not all the chips have a good input protection.

Mauro

[mauropenasa]

If it's of interest,I publish the complete "kit" of this circuit, for the beginners that have not the halves to draw the PCB. The circuit is done with traditional components, on 100*160 single layer board and is complete of loudspeakers protection and power supply( misses only the transformer ). This circuit is a synthesis of my vision on: GC, Power supply (for GC) and ground loop. Naturally it may it serve as base of evaluation for other configurations.
To build the circuit it may use the draw (bottom copper, top view) on transparent paper and behaviour the photo-impression ( or furnish the draw to firms specialized in PCB).

Ciao

Mauro

[mauropenasa]

The copper pCB Draw (600dpi pdf)...

[Russ White]

You don't how badly I want a few of those boards!!!