6.3V DC can you explain to me

[abbey road d enfer]

thank you both for your involvement
the potentiometer is a good idea
my project is the passive REDD47 + REDD EQ
the preamp has 3 lamps

Ah OK, so I had read correctly.

1x EF 86 (6.3v 200mA)
2x E88CC (6.3V 300mA each)

My datasheet for E88CC says 365mA.

tell me if my calculation of theoretical resistance is good
200mA+300mA+300mA=800mA
6.3Vac x 1.414= 8.9V -2V (diodes) = 6.9V-6.3V =0.6V/0.8A=0.75 R
the value seems wrong to me
I don't see or is it wrong?

Correct. I made a mistake in my simulation, now it confirms even less than 0.75 ohm. Actually 0.15 ohm.
But here, we're reaching the limits of simulation because we miss some data like xfmr leakage inductance, ESR of capacitors, accurate diode behaviour.
One big factor is how the xfmr reacts to load. If it's rated at 6.3V for 2 Amps, the voltage will be higher if drawing less.
All this must be confirmed by experimentation.

 

[BOB42]

Thanks a lot
I have the answer on the choice of 6.3V DC and the correction of my diagram.
the value of the resistances will be fixed during the tests.
I will come back to you with the diagram of the complete power supply.
See you soon
BOB

 

[Gavin Pursinger]

THX GUYS...THIS ALSO HELPS ME IN MY WORK
G

 

[Matador]

You can elevate the center tap of the hum balancing resistors by sending to a positive voltage rather than ground. Somewhere in the 40-60V range works well, and this in practice is nearly as good as DC heaters without all of the extra circuitry and heat that entails.

 

[BOB42]

hello
can you make a sketch for me to understand
thank you
BOB

 

[GussyLoveridge]

I think this is the basic idea. I often hesitate to add to these conversations as I don't want to put incorrect information out there or send someone down the wrong path. But I think this is close...Don't hesitate to chew this up if I'm way off. Normally I don't think we want DC on our potentiometers, but I think this is okay because you just set it for the lowest noise and don't change it (unless you change your tubes?) Either way, it's not a control that we're adjusting regularly. Again, I could be way off.

 

[BOB42]

Thanks a lot

BOB